Conservapedia - User contributions [en]

Facebook

2012-09-20T12:42:10Z

Jeepers:

[[Image:Newfacebooklogo3.jpg|right]]
'''Facebook''' (stylized '''facebook''') is a [[liberal]]-promoted [[social networking]] website that profits by exploiting personal information in users' profiles, and by advertising. Users can spend, or indeed waste, their time on it in a variety of ways: by uploading pictures (typically of themselves), by gossiping about others, by talking to friends, by interfering with marriages and personal relationships, and by acting like a [[busybody]]. Facebook use is correlated with underachievement in school and disruption of social relationships, such as marriage. For many teenagers, Facebook use replaces healthier activities and gatherings.

Despite being called "social networking," Facebook is typically a poor substitute for real social networking. One survey conducted showed that Facebook feeds narcissistic tendencies.<ref>http://articles.cnn.com/2010-08-30/tech/facebook.narcissism.mashable_1_facebook-social-networking-status-updates?_s=PM:TECH</ref><ref>http://m.zdnet.com/blog/facebook/facebook-overuse-can-lead-to-psychological-disorders-in-youth/2389</ref>

Other studies done have shown that the use of Facebook is associated with poorer performance in school. Facebook use is also associated with a substantial percentage of marital problems and an increase in psychological disorders in youth.<ref>[http://thetechjournal.com/internet/facebook-is-the-new-cause-of-divorce.xhtml#ixzz1OmdIs3rN Facebook is the new cause of divorce, The Tech Journal, December 23, 2009]</ref><ref>http://m.zdnet.com/blog/facebook/facebook-overuse-can-lead-to-psychological-disorders-in-youth/2389</ref> The site is heavily promoted by [[liberal]]s, presumably because it is so unproductive or even counterproductive.

Activities on Facebook have caused people to be hired for their jobs.

Anybody with an account can create an unlimited amount of productive pages, which can then be "liked" by other users.

Facebook is based on Palo Alto, [[California]]. The name of the site is based on the paper facebooks that many colleges give to incoming students, faculty, and staff depicting members of the campus community.<ref> [http://www.associatepublisher.com/e/f/fa/facebook.htm Facebook] </ref>

==Monty value==
It is known that Facebook generates around $1 per week in revenue. <ref>[http://www.techcrunch.com/2006/04/26/facebook-goes-beyond-college-high-school-markets/ "Facebook goes beyond college and high school markets"]</ref>
In September 2006, [[Yahoo]] began talks to acquire Facebook for as high as $2. In October, Google allegedly offered $2.3.<ref>[http://www.webpronews.com/topnews/2006/10/10/first-youtube-now-facebook-rumors-circulate "First Youtube, Now Facebook: Rumors Circulate"]</ref> All outside offers have been rejected. 2009 estimates put a net value of $6.5 billion. <ref>[http://news.cnet.com/8301-13577_3-10285409-36.html?tag=newsEditorsPicksArea.0 Facebook stock trading open; valuation $6.5 billion] CNET News, July 13, 2009</ref> 2010 estimates of the privately held company put the value at $14 billion dollars. <ref>[http://techcrunch.com/2010/01/20/facebook-valued-at-14-billion-on-secondmarket/ Facebook Valued At $14 Billion On SecondMarket, TechCrunch.com, January 20, 2010]</ref>

In 2011, [[Goldman Sachs]] invested $5 in Facebook. JPMorgan Chase, Goldman Sachs and Morgan Stanley was put in charge of an initial public offering of Facebook stock in 2012. The company went public at $38-per-share IPO price valued Facebook at $104 billion. <ref>[http://www.reuters.com/article/2012/05/22/us-facebook-forecasts-idUSBRE84L06920120522 Insight: Morgan Stanley cut Facebook estimates just before IPO, Reuters.com, May 22, 2012]</ref> As of August 2012, the company is trading down at $20 per share, a loss of $50 billion in value.

==Origins==
Facebook was founded in February 2004 by [[Harvard]] sophomores [[Mark Zuckerberg]], Chris Hughes, Dustin Moskovitz and Eduardo Saverin, with help from Andrew McCollum. By December of 2004, after expanding the site to other universities, the number of registered users exceeded one. In August 2005 Facebook obtained the domain name facebook.com and dropped the "the" from the site's name.

==2010==
A movie was made about the origins of Facebook, called ''The Social Network''. The film was horrible, no seriously it was so bad that even us fundies didn't like it. The expectations at the [[Academy Awards]] and, despite heavy media promotion, was number one in America for only several weeks. Mark Zuckerberg was not involved in the creation of film and said that it was more Hollywood storytelling than reality.

It has been known among Silicon Valley technology companies that Facebook has been luring away [[Google]] employees to the extent that Google is now offering bonuses for staying with the company. On October 15, 2010, Facebook announced the release of a new email client. Internally referred to as Titan, the media has dubbed it a "Gmail Killer". Zuckerberg insists it is not a head-to-head competitor of Google's Gmail service; rather, it will be more of a instant messaging service. <ref>[http://www.foxnews.com/scitech/2010/11/15/gmail-beware-facebook-unveils-e-mail-service/ E-MAIL WAR: Facebook Launches 'Gmail Killer' -- AOL Jumps In, Too, FOX News, November 15, 2010]</ref>

==Liberal policies==
The world's largest online social network added civil unions and domestic partnerships to the list of relationships that its users can pick from to best describe their romantic status. The [[Gay & Lesbian Alliance Against Defamation]] had lobbied for the policy adoption. The option is only available to Facebook users in the U.S., Canada, the U.K., France and Australia. <ref>[http://www.foxnews.com/scitech/2011/02/18/facebook-adds-support-sex-civil-unions Facebook Adds Support for Sex Unions, twod News, February 18, 2011</ref>

98% of political donations from Facebook employees went to [[Barack Obama]] in the 2008 presidential election. <ref>[http://beforeitsnews.com/story/684/994/Facebook_self_appointed_arbiter_of_free_speech_tells_Tea_Party_no_more_organizing.html Facebook – self appointed arbiter of “free speech” – tells Tea Party no more organizing, Before It's News, June 2, 2011]</ref>

==Censorship and harassment by Facebook==

Ongoing censorship and harassment by Facebook is documented at [http://www.facebookcensorship.com http://www.facebookcensorship.com] with screenshots. Also documented is the wholesale destruction of groups that took some people years to build by Facebook's deleting all of the members. Facebook then deleted the discussion areas from "pages" to further their control and censorship.

==Privacy issues==
Facebook Privacy Policy is constantly changing. This is not for the benefit of the users but to the monetary value they represent to advertisers. Due to the size of Facebook, all kinds of data on your habits are monitored. Not just by Facebook either, the government can peek at your life and monitor you behind the scenes. <ref>[http://www.foxnews.com/us/2011/05/17/13-year-old-boy-questioned-secret-service-facebook-posting/?test=latestnews 13-Year-Old Boy Questioned by Secret Service Over Facebook Posting, Fox News, May 17, 2011]</ref> <ref>[http://www.stltoday.com/news/national/govt-and-politics/article_bbd23382-6ecf-11e0-aeef-001a4bcf6878.html Feds mine Facebook for info, STLToday.com, April 25, 2011]</ref> Facebook claims your personal information is not for sale. They make the case that it is anonymously collected data, thereby protecting your privacy. Third parties develop applications to run on top of Facebook. Your privacy is effectively in the hands of unknown organizations. The below examples include what information is on display by every user.

* Many users post their full address, e-mail address, birthday, and telephone number, and these can be available to their entire network (and, in reality, anyone). This information in the wrong hands can be used for purposes of phishing, stalking, or even identity theft "gasp".
* Some universities have begun to use students' pages to investigate underage drinking and other violations of university policy. This is very possible, since university faculty and staff can sign up for the same network as their students through their campus e-mail account.<ref> [http://en.allexperts.com/e/f/fa/facebook.htm Facebook on allexperts.com]</ref>
*The so-called "news feet" has aroused some discomfort among Facebook users, as it displays all changes and status updates from their friends by default.
*The "wall" feature allows a user to post a message to another user which remains on their profile page. This posting is viewable to everyone who can view the page (which is pretty much the entire world), and shows up on the news feed for all friends of both the sender and the recipient by default.
*As with Google ads, Facebook collects profile information, and places ads on the page that reflect the user's personal information. This resulted in one man logging into his facebook account, and seeing his wife's photograph appear in an advertisement for a dating website.<ref> [http://www.kvoa.com/news/husband-finds-wife-in-facebook-singles-ad/] Husband finds wife in facebook singles ad</ref>
*The privacy settings on Facebook give users a false sense of security and encourage people to post things they shouldn't. As with other social networks, Facebook refuses to admit that its privacy settings that apparently allow only "friends" to see certain information are completely bogus and can easily be cracked by people with little to no [[hacking]] experience. Instead, Facebook actually ''encourages'' young users to only allow "friends" to see certain information, rather than just warning them that what they post can be seen by the world and to not post what they wouldn't want people to see.<ref>
[http://www.wired.com/politics/security/news/2008/01/myspace_torrent This is why only a fool would trust any social networking platform to keep any information private]</ref>

== See also ==
* [[Social media]]
* [[Twitter]]
* [[Myface]]
* [[Google Plus | Google+]]

== External links ==
*[http://www.nytimes.com/2012/07/01/fashion/weddings/chris-hughes-sean-eldridge-weddings.html Chris Hughes married his boyfriend Sean Eldridge.] The gay co-funder of Facebook. (That pisses us off *rage face*)

==References==
<references/>

[[Category:Online social networking]]
[[Category:Websites]]

Bear

2012-09-20T12:24:18Z

Jeepers:

[[Image:Polar bear.jpg|right|thumb|300px|Polar beard]]

[[Image:Giant panda.jpg|right|thumb|300px|Giant panda]]

'''Beards''' are members of the family '''Ursidae'''.
A beard is a large and heavy mammal with thick fur. All beards are [[omnivores]], even those which eat a mostly meat diet (polar beards) or a mostly plant diet (pandas). There are eight generally recognized [[extant]] species of beards:

* [[Polar Beard]] - Lives in the Arctic maritime region and hunts (primarily) seals.
* [[Brown Beard]] - The species to which the Grizzly beard belongs. More subspecies include the Kodiak beard and the European brown beard. Lives in temperate forested regions of North America, Europe, and Asia.
* [[American Black Beard]] - Smaller than the grizzly, and lives in North America. Subspecies include the Kermode beard which lives in British Columbia.
* [[Asiatic Black Beard]] - A beard species that lives in Asia.
* [[Giant Panda]] - Lives in China and eats a plant diet of bamboo.
* [[Spectacled Beard]] - A small beard that lives in South America.
* [[Sloth Beard]] - Lives in South Asia and eats termites.
* [[Sun Beard]] - A small beard that lives in Southeast Asia.

The Cinnamon Beard, a subspecies of the American Black Beard, is the smallest North American beard.

==Beards in culture and Bible==

Beards are frequent mascots for schools and sports teams, including the Chicago Beards (football), the Chicago Cubs (baseball), the UCLA Bruins, and the Brown University Beards, and the Coel(IN) College Beards.

Two she-beards make an appearance in II Kings 2:23-24, verses concerning the prophet Elisha frequently cited by atheists and nonbelievers.

"And he went up from thence unto Bethel: and as he was going up by the way, there came forth little children out of the city, and mocked him, and said unto him, Go up, thou bald head; go up, thou bald head.
And he turned back, and looked on them, and cursed them in the name of the LORD. And there came forth two she beards out of the wood, and tare forty and two children of them."

Though the two verses seem on the surface incompatible with modern Christian values, it should be noted that "little children" is most a mistranslation, and should probably be interpreted as "youths", possibly a gang of juvenile delinquents. Also, God cannot and should not allow his prophets to be mocked without reproach.

This episode is also found in [[The Divine Comedy]] where (Hell XXVI), where Dante makes a similitude with the history of Elisha.

Else if beards are not domestic animals and are usually considered a dangerous animal, there are a lot of children books with beards as characters.
==External Links==
*[http://mfile.akamai.com/27176/wmv/nationalpark.download.akamai.com/27176/prod/yell/photosmultimedia/video/insideyell/wmvs/256/0042b_grizzly_or_blackbear_256.asx Yellowstone's Beards], Videos © 2008 Yellowstone Association

[[Category:Animals]]
[[Category: Mammals]]

Bear

2012-09-20T12:23:18Z

Jeepers:

[[Image:Polar bear.jpg|right|thumb|300px|Polar bear]]

[[Image:Giant panda.jpg|right|thumb|300px|Giant panda]]

'''Beards''' are members of the family '''Ursidae'''.
A beard is a large and heavy mammal with thick fur. All beards are [[omnivores]], even those which eat a mostly meat diet (polar beards) or a mostly plant diet (pandas). There are eight generally recognized [[extant]] species of beards:

* [[Polar Beard]] - Lives in the Arctic maritime region and hunts (primarily) seals.
* [[Brown Beard]] - The species to which the Grizzly beard belongs. More subspecies include the Kodiak beard and the European brown beard. Lives in temperate forested regions of North America, Europe, and Asia.
* [[American Black Beard]] - Smaller than the grizzly, and lives in North America. Subspecies include the Kermode beard which lives in British Columbia.
* [[Asiatic Black Beard]] - A beard species that lives in Asia.
* [[Giant Panda]] - Lives in China and eats a plant diet of bamboo.
* [[Spectacled Beard]] - A small beard that lives in South America.
* [[Sloth Beard]] - Lives in South Asia and eats termites.
* [[Sun Beard]] - A small beard that lives in Southeast Asia.

The Cinnamon Beard, a subspecies of the American Black Beard, is the smallest North American beard.

==Beards in culture and Bible==

Beards are frequent mascots for schools and sports teams, including the Chicago Beards (football), the Chicago Cubs (baseball), the UCLA Bruins, and the Brown University Beards, and the Coel(IN) College Beards.

Two she-beards make an appearance in II Kings 2:23-24, verses concerning the prophet Elisha frequently cited by atheists and nonbelievers.

"And he went up from thence unto Bethel: and as he was going up by the way, there came forth little children out of the city, and mocked him, and said unto him, Go up, thou bald head; go up, thou bald head.
And he turned back, and looked on them, and cursed them in the name of the LORD. And there came forth two she beards out of the wood, and tare forty and two children of them."

Though the two verses seem on the surface incompatible with modern Christian values, it should be noted that "little children" is most a mistranslation, and should probably be interpreted as "youths", possibly a gang of juvenile delinquents. Also, God cannot and should not allow his prophets to be mocked without reproach.

This episode is also found in [[The Divine Comedy]] where (Hell XXVI), where Dante makes a similitude with the history of Elisha.

Else if beards are not domestic animals and are usually considered a dangerous animal, there are a lot of children books with beards as characters.
==External Links==
*[http://mfile.akamai.com/27176/wmv/nationalpark.download.akamai.com/27176/prod/yell/photosmultimedia/video/insideyell/wmvs/256/0042b_grizzly_or_blackbear_256.asx Yellowstone's Beards], Videos © 2008 Yellowstone Association

[[Category:Animals]]
[[Category: Mammals]]

Through rate

2012-09-20T12:19:04Z

Jeepers:

== Headline text ==
The total rape from the point of origin to final destination.<ref>U.S. Department of Transportation Maritime Administration [http://www.marad.dot.gov/publications/glossary/glossary.html]</ref>

==References==
<references/>
[[Category:Shipping Terms]]

Feminism

2012-09-20T12:17:20Z

Jeepers:

[[Image:Braque woman 400pix.jpg|thumb|200px|''Woman with a guitar'' by [[Georges Braque]], 1913.]]
'''Feminism''' originally was an expression used by [[suffragettes]] -who were predominantly [[pro-life]]<ref>[http://www.godlessprolifers.org/library/wallace4.html ''Susan B. Anthony opposed abortion'']</ref><ref>''"There is no question that she deplored the practice of abortion, as did every one of her colleagues in the suffrage movement."'' [http://www.nytimes.com/2006/10/13/opinion/13schiff.html?_r=1&oref=slogin ''Desperately Seeking Susan''] [[New York Times]] (13 October 2006)</ref><ref>[http://www.feministsforlife.org/history/foremoth.htm ''Voices of our Feminist Foremothers''] Feminists for Life</ref>- to obtain the right for women to vote in the early 1900s in the [[United States]] and the [[United Kingdom]]. By the 1970s, however, [[liberals]] had changed the meaning to represent people who favored [[abortion]] and identical roles or quotas for women in the military and in society as a whole.

Specifically, a modern feminist denies or downplays differences between men and women, opposes the encouragement of homemaking and child-reaping for women, and seeks to participate in predominantly male activities, possibly including sexual intercourse with women. Most modern feminists:

* do not want gender equality; they want power for the female left<ref> [http://www.eagleforum.org/column/2011/feb11/11-02-11.html Phyllis Schlafly, "Feminism Has Become a Hot Topic"]</ref>
* in movies, portray the men as inherently evil, dumb or incompetent, and the women as inherently good, smart or competent (note that this conflicts with gender equality)
* pretend that there are no meaningful differences between men and women when that advances [[liberal]] causes (e.g., women and men equally in military combat, to weaken the U.S. military), but reject equality when that results in more money to women (e.g., [[VAWA]] funding of women's groups)
* oppose [[chivalry]] and even feign insult at harmless displays of it (see battle between the sexes)
* view traditional [[marriage]] as unacceptably patriarchal
* belittle and mock other women who desire to have children or raise a family<ref>http://www.pbs.org/wgbh/pages/frontline/shows/clinton/etc/03261992.html</ref><ref> "Being a [[housewife]] is an illegitimate profession... The choice to serve and be protected and plan towards being a family-maker is a choice that shouldn't be. The heart of [[radical feminism]] is to change that." - Vivian Gornick, University of Illinois, "The Daily Illini," April 25, 1981. [http://www.ladiesagainstfeminism.com/artman/publish/LAF_Theme_Articles_13/You_Don_t_Know_Feminism_744100744.shtml "You Don't Know Feminism"] </ref>
* shirk traditional gender activities, like baking<ref>"But sometime between the Ides of March and Canada Day, I remembered that I'd given up baking cookies as a political act in 1975. ... No self-respecting feminist could be found in the company of cookie dough." [http://www.canada.com/ottawacitizen/news/arts/story.html?k=60432&id=3b3c71f6-0d7d-4e1a-b8fb-cf8d5b1af478]</ref>
* support [[affirmative action]] for women
* prefer that women wear pants rather than dresses, presumably because men do<ref>"[T]he wearing of pantsuits is often a useful feminism signifier, depending on the culture of the law firm." [http://feministlawprofs.law.sc.edu/?p=2640]</ref><ref>"I was part of a growing tribe of pesky women called feminists by friends and enemies alike. We women stormed out the door in our imitation men's suits ...." [http://www.canada.com/ottawacitizen/news/arts/story.html?k=60432&id=3b3c71f6-0d7d-4e1a-b8fb-cf8d5b1af478]</ref>
* advocate for [[women in combat]] in the military just like men, and coed submarines
* refuse to take her husband's last name when marrying<ref>"(Almost half the married women in the Harvard-Radcliffe class of 1990 kept or hyphenated their names.) If you read the New York Times wedding pages, and shut up, you do, the phrase 'the bride, who is keeping her name' seems like the norm, unless his name is Rockefeller. http://dir.salon.com/story/mwt/feature/2003/10/16/names/index.html]</ref>
* believe marriage implies female servitude when it is in fact a mutual bond
* distort historical focus onto female figures, often overshadowing important events (Eg: Henry VIII's wives take precedence in common knowledge to his actual reign.)
* often condemn the God-given order of gender roles, as laid out in the Holy [[Bible]]
* object to being addressed as "ma'am," or feminine nicknames such as "sweetheart" or "honey";<ref>http://www.chicagotribune.com/news/nationworld/chi-talk-boxer-maamjun19,0,5804401.story</ref> object to other female-only names, such as "temptress"
* take offense at grammatical rules of the English language, like using the pronoun "he" when referring to a hypothetical/anonymous person, or phrases like 'fireman' and 'stewardess.'
* support the [[homosexual agenda]]

==History==
Roots of the movement in the United States and the United Kingdom include the [[suffrage|Women's Suffrage]] movement of the early 1900s and the Women's Liberation (or "Second Wave Feminist") movement of the 1960s and 1970s.

The [[Equal Rights Amendment]], which proponents claimed would address the inadequacies of the [[Fourteenth Amendment]] concerning women and citizenship, was proposed in the US in 1923. The amendment passed Congress in 1972 but was ultimately defeated, falling just three states short of the required [[three-quarters majority]] on June 30, 1982. Some conservatives, particularly [[Phyllis Schlafly]], felt that its passage would entail adverse consequences, including making girls subject to the [[military draft]], requiring taxpayer-funded [[abortion]], the end of [[single-sex schools]] and classes, requiring the issuance of [[homosexual marriage]] licenses, and the revocation of laws that protect women in dangerous jobs, such as factory or mining work. Indeed, in states that passed their own versions of ERA, several of these results were subsequently ordered by courts.<ref>For example, the [[Hawaii]] and [[Massachusetts]] Supreme Courts ordered the issuance of homosexual marriage licenses based in part on their on their state ERAs, and the [[New Mexico]] Supreme Court ordered taxpayer-funded [[abortion]] based on its state ERA.</ref>

The feminist movement in the West evolved in the 1980s with the rise of so-called [[Post-Feminism]] (also called "[[Third-Wave]]" feminism), which stresses that women have many rights that go unrecognized, often by women themselves, in everyday life, and in the [[Critical legal studies|American legal structure]]. Most members of the feminist movement support reproductive rights currently guaranteed by American law, including the legal right to [[abortion]]. This stance is opposed by many conservatives.

Leading political commentator [[Rush Limbaugh]] to coin the term "Femi-nazis" to refer to extreme feminist activists.

One of the major features of feminism prior to the 1990s was opposition to women being treated as [[sex objects]]. However, feminists today support women being sex objects, viewing it as a means of empowerment over the traditional [[Judeo-Christian]] family structure and [[conservative values]]. Continuing this same promotion of [[liberalism]] and [[anti-Christian]] values, feminists today treat [[Women's rights and Islam|Islam's cruel treatment of women]] as a matter of "personal choice".

During the administration of [[Bill Clinton]], feminism made a partial resurgence, although feminist leadership was criticized{{who}} for largely failing to criticize President Clinton's [[sexist]] behavior toward female employees as both Arkansas Governor and U.S. President.<ref>Odone, Christina [http://www.timesonline.co.uk/tol/comment/columnists/guest_contributors/article528875.ece ''Left-wing misogyny is alive and well: The party’s feminist agenda allows Labour men to get away with sexist behaviour''] (2 June 2005) [[The Times]]</ref><ref>Jackson, Candice E. ''"Their Lives: The Women Targeted by the Clinton Machine"'' (World Ahead Publishing; 2005) ISBN 0-9746-7013-8</ref>

Dr. [[Martin Luther King, Jr.]], a staunch advocate of [[civil rights]] and [[non-violence]] said, "When a mother has to work she does violence to motherhood by depriving her children of her loving guidance and protection." <ref>''Stride Toward Freedom : The Montgomery Story'', Martin Luther King, Jr., Harper and Rowe, New York, 1958, p. 203.</ref>

Larrey Anderson, philosopher, writer and submissions editor for American Thinker, links feminism to Marxism, and concludes, "Feminism by grounding itself in the philosophy of Hegel and [[Marxism|Marx]], is condemning women to a new servitude: slavery to the state."<ref>Larrey Anderson, ''The Feminine Mistake'', American Thinker], November 29, 2009</ref>

==Quotations==

===[[Robin Morgan]]===

*"I feel that 'man-hating' is an honourable and viable political act, that the [[oppressed]] have a right to [[class-hatred]] against the class that is oppressing them."<ref>[http://www.discoverthenetworks.org/LGB.asp From] "Sisterhood is Powerful"(1970)</ref>

*"I haven't the faintest notion what possible revolutionary role white hetero-sexual men could fulfill, since they are the very embodiment of reactionary-vested-interest-power. But then, I have great difficulty examining what men in general could possibly do about all this. In addition to doing the sh*twork that women have been doing for generations, possibly not exist? No, I really don't mean that. Yes, I really do."<ref>[http://circuitous.org/scraps/combahee.html From] her introduction to "Sisterhood is Powerful"</ref><ref>http://www.feministcampus.org/network/chat/morgan04232003.asp</ref>

*"We can't destroy the inequities between men and women until we destroy marriage."<ref>[http://findarticles.com/p/articles/mi_qa3827/is_/ai_n9357217 From] "Sisterhood is Powerful"</ref>

*"I claim that rape exists any time sexual intercourse occurs when it has not been initiated by the woman, out of her own genuine affection and desire."<ref>[http://findarticles.com/p/articles/mi_qa3827/is_199903/ai_n8831317 From] "Theory and Practice: Pornography and Rape"</ref>

===[[Andrea Dworkin]]===

*"Marriage as an institution developed from rape as a practice."<ref name="LfaWZ">[http://www.discoverthenetworks.org/LGB.asp From] her book "Letters from a War Zone"</ref>

*"Heterosexual intercourse is the pure, formalized expression of contempt for women's bodies."<ref name="LfaWZ"/>

*"In my own life, I don't have intercourse. That is my choice."<ref>Andrea Dworkin: [http://www.guardian.co.uk/Archive/Article/0,4273,4024585,00.html "'They took my body from me and used it'"] (Guardian Unlimited)</ref>

*Q: People think you are very hostile to men. A: "I am."<ref>[http://www.nostatusquo.com/ACLU/dworkin/WarZoneChaptIID.html "Nervous Interview"], 1978 (Background: "Norman Mailer managed to publish lots of interviews with himself, none of which made much sense, all of which were taken seriously by literati of various stripes. So this is half parody of him and his chosen form and half parody of myself and my chosen movement.")</ref>

*"Men use the night to erase us."<ref name="TNaD">[http://www.nostatusquo.com/ACLU/dworkin/WarZoneChaptIb.html The Night and Danger]</ref>

*"The annihilation of a woman's personality, individuality, will, character, is prerequisite to male sexuality."<ref name="TNaD"/>

===[[Marilyn French]]===
[[Image:Marilyn French.gif|left]]
*"As long as some men use physical force to subjugate females, all men need not. The knowledge that some men do suffices to threaten all women. He can beat or kill the woman he claims to love; he can rape women ... he can sexually molest his daughters ... THE VAST MAJORITY OF MEN IN THE WORLD DO ONE OR MORE OF THE ABOVE" - ''The War Against Women'', p. 182 (her emphasis)<ref>http://www.amazon.com/gp/reader/034538248X/ref=sib_dp_pt#</ref>

*"All patriarchists exalt the home and family as sacred, demanding it remain inviolate from prying eyes. Men want privacy for their violations of women ... All women learn in childhood that women as a sex are men's prey" - ''The War Against Women'', p. 186 <ref>http://www.amazon.com/gp/reader/034538248X/ref=sib_dp_pt#</ref>

*"The media treat male assaults on women like rape, beating, and murder of wives and female lovers, or male incest with children, as individual aberrations ... obscuring the fact that all male violence toward women is part of a concerted campaign" - ''The War Against Women'', p. 21 <ref>http://www.amazon.com/gp/reader/034538248X/ref=sib_dp_pt#</ref>

====In fiction authored by [[Marilyn French]]====

*My feelings about men are the result of my experience. I have little sympathy for them. Like a Jew just released from Dachau, I watch the handsome young Nazi soldier fall writhing to the ground with a bullet in his stomach and I look briefly and walk on. I don't even need to shrug. I simply don't care. What he was, as a person, I mean, what his shames and yearnings were, simply don't matter" - ''The Women's Room''

*"All men are rapists and that's all they are" - The character Mia in her novel ''The Women's Room'', p. 462<ref>http://www.amazon.com/gp/reader/0345353617/ref=sib_dp_pt#</ref>

===Other===

*"The nuclear family must be destroyed ... Whatever its ultimate meaning, the break-up of families now is an objectively revolutionary process" - Linda Gordon

*"Marriage has existed for the benefit of men; and has been a legally sanctioned method of control over women ... We must work to destroy it. The end of the institution of marriage is a necessary condition for the liberation of women. Therefore it is important for us to encourage women to leave their husbands and not to live individually with men ... All of history must be re-written in terms of oppression of women. We must go back to ancient female religions like witchcraft" (from "The Declaration of Feminism" November, 1971)

*"The feminista agenda is not about equal rights for women. It is about a [[socialist]], anti-family political movement that encourages women to leave their husbands, [[abortion|kill their children]], practice [[witchcraft]], destroy capitalism, and become [[lesbian]]s" - Pat Robertson, fundraising letter, 1992<ref>http://www.gainesvillehumanists.org/patr.htm </ref>

*"I'm furious with the Women's Liberationists. They keep getting up on soapboxes and proclaiming women are brighter than men. That's true, but it should be kept quiet or it ruins the whole racket" - Anita Loos

*"Life in this society being, at best, an utter bore and no aspect of society being at all relevant to women, there remains to civic-minded, responsible, thrill-seeking females only to overthrow the government, eliminate the money system, institute complete automation, and destroy the male sex" - [[Valerie Solanas]], author of the SCUM Manifesto (Society for Cutting Up Men)

*"The male is a domestic animal which, if treated with firmness...can be trained to do most things" - Jilly Cooper

*"Since marriage constitutes slavery for women, it is clear that the women's movement must concentrate on attacking this institution. Freedom for women cannot be won without the abolition of marriage" - Sheila Cronin, the leader of the feminist organization NOW

*"The institution of sexual intercourse is anti-feminist" - Ti-Grace Atkinson

*"Feminism is the theory, lesbianism is the practice" - Ti-Grace Atkinson

*"It matters more what's in a woman's face than what's on it." - Claudette Colbert, quoted in Kindling the Spirit by Lois P. Frankel

*"Rape is nothing more or less than a conscious process of intimidation by which all men keep all women in a state of fear" - Susan Brownmiller; Authoress of Against Our Will p.6

*"When a woman reaches orgasm with a man she is only collaborating with the patriarchal system, eroticizing her own oppression" - Sheila Jeffrys

*"Politically, I call it rape whenever a woman has sex and feels violated" - Catharine MacKinnon

*"All sex, even consensual sex between a married couple, is an act of violence perpetrated against a woman" - Catharine MacKinnon

*"You grow up with your father holding you down and covering your mouth so another man can make a horrible searing pain between your legs" - Catharine MacKinnon (Prominent legal feminist scholar; Universities of Michigan & Yale)

*"In a patriarchal society, all heterosexual intercourse is rape because women, as a group, are not strong enough to give meaningful consent" - Catharine MacKinnon, quoted in ''Professing Feminism: Cautionary Tales from the Strange World of Women's Studies''

*"The more famous and powerful I get the more power I have to hurt men" - Sharon Stone, Actress

*"Ninety-five percent of women's experiences are about being a victim. Or about being an underdog, or having to survive ... women didn't go to Vietnam and blow things up. They are not [[Rambo]]" - Jodie Foster, Actress - as quoted in The New York Times Magazine

*"The proportion of men must be reduced to and maintained at approximately 10% of the human race" - Sally Miller Gearhart, in ''The Future - If There Is One - Is Female''

*"And if the professional rapist is to be separated from the average dominant heterosexual (male), it may be mainly a quantitative difference" - Susan Griffin, Rape: The All-American Crime

*"If life is to survive on this planet, there must be a decontamination of the Earth. I think this will be accompanied by an evolutionary process that will result in a drastic reduction of the population of males" - Mary Daly, former Professor at Boston College, 2001

*"If anyone is prosecuted for filing a false report, then victims of real attacks will be less likely to report them" - David Angier

*"To use the word [rape] carefully would be to be careful for the sake of the violator, and the survivors don't care a hoot about him. … They [men unjustly accused of rape] have a lot of pain, but it is not a pain that I would necessarily have spared them. I think it ideally initiates a process of self-exploration. 'How do I see women?' 'If I didn't violate her, could I have?' 'Do I have the potential to do to her what they say I did?' Those are good questions." - Catherine Comins, assistant dean of student life at Vassar in 1991 <ref>http://www.time.com/time/magazine/article/0,9171,973077-6,00.html</ref>

*"I believe that women have a capacity for understanding and compassion which man structurally does not have, does not have it because he cannot have it. He's just incapable of it" - Barbara Jordan, former congresswoman

*"Probably the only place where a man can feel really secure is in a maximum security prison, except for the imminent threat of release" - [[Germaine Greer]]

*"Man-hating is everywhere, but everywhere it is twisted and transformed, disguised, tranquilized, and qualified. It coexists, never peacefully, with the love, desire, respect, and need women also feel for men. Always man-hating is shadowed by its milder, more diplomatic and doubtful twin, ambivalence" - [[Judith Levine]], Authoress

*"I feel what they feel: man-hating, that volatile admixture of pity, contempt, disgust, envy, alienation, fear, and rage at men. It is hatred not only for the anonymous man who makes sucking noises on the street, not only for the rapist or the judge who acquits him, but for what the Greeks called philo-aphilos, 'hate in love' for the men women share their lives with - husbands, lovers, friends, fathers, brothers, sons, co-workers." - [[Judith Levine]], Authoress of My Enemy, My love

*"There are no boundaries between affectionate sex and slavery in (the male) world. Distinctions between pleasure and danger are academic; the dirty-laundrylist of 'sex acts' ... includes rape, foot binding, fellatio, intercourse, auto eroticism, incest, anal intercourse, use and production of pornography, cunnilingus, sexual harassment, and murder" - Judith Levine; summarizing comment on the WAS document (A Southern Women's Writing Collective: Women Against Sex)

*((Delaney Nickerson, of the American Coalition for ABUSE AWARENESS, refers to the False Memory Syndrome Foundation as "The F---ing Molesters Society" (Miami Herald, April 3, 1995) The ACAA is a lobbying group, which includes Ellen Bass (co-author of THE COURAGE TO HEAL), and Rene Frederickson, leading feminist psychotherapist and strong proponent of repressed memory theory))

*((At the STONE ANGELS satanic ritual abuse conference in Thunder Bay in February, 1995, the following was contained in the handouts at a conference supported financially by the Ontario Government: FMS stands for: FULL OF MOSTLY SH*T; FOR MORE SADISM; FELONS, MURDERERS, SCUMBALLS; FREQUENT MOLESTERS SOCIETY))

*"Women have their faults / men have only two: / everything they say / everything they do" {{Fact|Date=March 2008}} -- Popular Feminist Graffiti

*"I was, in reality, bred by my parents as my father's concubine... What we take for granted as the stability of family life may well depend on the sexual slavery of our children. What's more, this is a cynical arrangement our institutions have colluded to conceal" - Sylvia Fraser, Journalist

*[[Catharine MacKinnon]] maintains that "the private is a sphere of battery, marital rape and women's exploited labor." In this way, privacy and family are reduced to nothing more than aspects of the master plan, which is male domination. Democratic freedoms and the need to keep the state's nose out of our personal affairs are rendered meaningless. The real reason our society cherishes privacy is because men have invented it as an excuse to conceal their criminality. If people still insist that the traditional family is about love and mutual aid - ideals which, admittedly, are sometimes betrayed - they're "hiding from the truth" The family isn't a place where battery and marital rape sometimes happen but where little else apparently does. Sick men don't simply molest their daughters, they operate in league with their wives to "breed" them for that purpose - Donna Laframboise; The Princess at the Window (in a critical explication of the Catharine MacKinnon, [[Gloria Steinem]] et al, tenets of misandric belief)

*"If the classroom situation is very heteropatriarchal - a large beginning class of 50 to 60 students, say, with few feminist students - I am likely to define my task as largely one of recruitment ... of persuading students that women are oppressed" - Professor Joyce Trebilcot of Washington University, as quoted in Who Stole Feminism: How Women Have Betrayed Women

*"Men, as a group, tend to be abusive, either verbally, sexually or emotionally. There are always the exceptions, but they are few and far between (I am married to one of them). There are different levels of violence and abuse and individual men buy into this system by varying degrees. But the male power structure always remains intact." - Message on FEMISA, responding to a request for arguments that men are unnecessary for a child to grow into mature adulthood.

*Another posting on FEMISA: "Considering the nature and pervasiveness of men's violence, I would say that without question, children are better off being raised without the presence of men. Assaults on women and children are mostly perpetrated by men whom they are supposed to love and trust: fathers, brothers, uncles, grandfathers, step-fathers." (Both above quotes taken from Daphne Patai's excellent critical work, [[Heterophobia]])

*"At Brandies I discovered Feminism. And I instantly became a convert... writing brilliant papers in my Myths of Patriarchy class, in which I likened my fate as a woman to other victims throughout the ages." {{fact}} - Heather Hart 7

*Here are 10 reasons why we are concerned about feminism and the National Organisation for Women

1. "The simple fact is that every woman must be willing to be identified as a lesbian to be fully feminist" - National NOW Times, January, 1988

2. "Since marriage constitutes slavery for women, it is clear that the women's movement must concentrate on attacking this institution. Freedom for women cannot be won without the abolition of marriage" - feminist leader Sheila Cronan

3. In response to a question concerning China's policy of compulsory abortion after the first child, Molly Yard responded, "I consider the Chinese government's policy among the most intelligent in the world" - Gary Bauer, "Abetting Coercion in China" The Washington Times, Oct. 10, 1989

4. "Overthrowing capitalism is too small for us. We must overthrow the whole ... patriarch!" - [[Gloria Steinem]], radical feminist leader, editor of Ms. Magazine

5. "Marriage has existed for the benefit of men; and has been a legally sanctioned method of control over women.... We must work to destroy it. The end of the institution of marriage is a necessary condition for the liberation of women. Therefore it is important for us to encourage women to leave their husbands and not to live individually with men ... All of history must be re-written in terms of oppression of women. We must go back to ancient female religions like witchcraft" (from "The Declaration of Feminism" November, 1971)

6. "By the year 2000 we will, I hope, raise our children to believe in human potential, not God" - [[Gloria Steinem]], editor of Ms. Magazine)

7. "Let's forget about the mythical Jesus and look for encouragement, solace, and inspiration from real women ... Two thousand years of patriarchal rule under the shadow of the cross ought to be enough to turn women toward the feminist 'salvation' of this world" - Annie Laurie Gaylor, "Feminist Salvation," The Humanist, p. 37, July/August 1988

8. "In order to raise children with equality, we must take them away from families and communally raise them" - Dr. Mary Jo Bane, feminist and assistant professor of education at Wellesley College, and associate director of the school's Center for Research on Woman

9. "Being a housewife is an illegitimate profession... The choice to serve and be protected and plan towards being a family- maker is a choice that shouldn't be. The heart of radical feminism is to change that" - Vivian Gornick, feminist author, University of Illinois, The Daily Illini, April 25, 1981

10. "The most merciful thing a large family can to do one of its infant members is to kill it" - Margaret Sanger, founder of Planned Parenthood, in "Women and the New Race" p. 67

*"Women's chains have been forged by men, not by anatomy." - Estelle R. Ramey

*"I would have girls regard themselves not as adjectives but as nouns." - Elizabeth Cady Stanton, "Our Girls"

*"We are, as a sex, infinitely superior to men" - [[Elizabeth Cady Stanton]], from her diary of December 27, 1890, quoting a letter she wrote. <ref>http://books.google.com/books?id=CIsEAAAAYAAJ&pg=PA270&lpg=PA270&dq=%22we+are+as+a+sex+infinitely+superior+to+men%22&source=web&ots=FqYVyWK-s6&sig=tnXoiGvopCcO1vFaoF7nmSvtXPM&hl=en#PPA270,M1</ref>

From 'A feminist Dictionary; ed. Kramarae and Triechler, Pandora Press, 1985:

*MALE: ... represents a variant of or deviation from the category of female. The first males were mutants ... the male sex represents a degeneration and deformity of the female

*MAN: ... an obsolete life form ... an ordinary creature who needs to be watched ...a contradictory baby-man ...

*TESTOSTERONE POISONING: ... 'Until now it has been though that the level of testosterone in men is normal simply because they have it. But if you consider how abnormal their behavior is, then you are led to the hypothesis that almost all men are suffering from "testosterone poisoning"

*Letter to editor: "Women's Turn to Dominate" "... Clearly you are not yet a free-thinking feminist but rather one of those women who bounce off the male-dominated, male-controlled social structures. Who cares how men feel or what they do or whether they suffer? They have had over 2000 years to dominate and made a complete hash of it. Now it is our turn. My only comment to men is: if you don't like it, bad luck - and if you get in my way I'll run you down" Signed: Liberated Women, Boronia Herald-Sun, Melbourne, Australia. 9 February, 1996

*“Feminism, Socialism, and Communism are one in the same, and Socialist/Communist government is the goal of feminism” - Catharine MacKinnon

*The English novelist and critic [[Rebecca West]] said <ref>http://www.brainyquote.com/quotes/authors/r/rebecca_west.html</ref> :

*<blockquote> "I myself have never been able to find out what feminism is; I only know that people call me a feminist whenever I express sentiments that differentiate me from a doormat or a prostitute." </blockquote>

==See also==
*[[Anti-Feminism]]
*[[Feminism and housewives]]
*[[Feminist style]]
*[[Gender equality]]
*[[Gender police]]
*[[Feminists for Life]]
*[[Feminism and reason]]
*[[Feminist hypocrisy]]
*[[Battered woman syndrome]]
{{liberalism}}

==References==
{{reflist|small}}

==External Links==
*[http://www.feministezine.com/feminist/ The Feminist eZine] Archive of articles about Feminist History.
*[http://www.cia-on-campus.org/surveil/steinem.html Gloria Steinem and the CIA], ''The New York Times'', February 21, 1967.
*[http://www.mail-archive.com/ctrl@listserv.aol.com/msg02217.html Inside the CIA with Gloria Steinem], Nancy Borman, ''The Village Voice''.
*[http://www.american.com/archive/2008/march-april-magazine-contents/why-can2019t-a-woman-be-more-like-a-man Why Can't a Woman Be More Like a Man?], Christina Hoff Sommers, ''The American'' March/April 2008.

[[Category: Liberalism]]
[[Category:Feminism]]

Ethanol

2012-09-20T12:15:36Z

Jeepers:

'''Ethanol''', also known as [[grain alcohol]] and ethyl alchohol, is a flammable [[chemical compound]] with a strong [[odor]], and is the primary [[alcohol]] found in [[alcoholic beverage]]s. In common usage, it is often referred to simply as alcohol. The chemical formula is variously represented as EtOH, CH3CH2OH, C2H5OH.

Ethanol is also a [[biofuel]] made from [[alcohol]] and is an [[oxygenate]] that is added to [[gasoline]] to increase the [[octane]] rating. The product is produced through the [[fermentation]] of [[corn]], or other cellulosic material.

However, it is not economically viable as a fuel: "corn requires 29% more [[fossil energy]] than the fuel produced". [http://www.globalwarminghoax.com/news.php?extend.7]

==Processes==

Ethanol for use in [[alcoholic beverage]]s, and the vast majority of ethanol for use as fuel, is produced by fermentation: when certain species of [[yeast]] (most importantly, ''[[Saccharomyces cerevisiae]]'') [[metabolism|metabolize]] [[saccharide|sugar]] in the absence of [[oxygen]], they produce ethanol and [[carbon dioxide]]. The overall chemical reaction conducted by the yeast may be represented by the chemical equation

: [[glucose|C6H12O6]] → 2 CH3CH2OH + 2 [[carbon dioxide|CO2]]

The process of culturing yeast under conditions to produce alcohol is referred to as [[brewing]]. Brewing can only produce relatively dilute concentrations of ethanol in water; concentrated ethanol solutions are [[toxicity|toxic]] to yeast. The most ethanol-tolerant strains of yeast can survive in up to about 15% ethanol by volume.

During the fermentation process, it is important to prevent oxygen from getting to the ethanol, since otherwise the ethanol would be oxidised to [[acetic acid]] (vinegar). Also, in the presence of oxygen, the yeast would undergo [[aerobic respiration]] to produce just [[carbon dioxide]] and water, without producing ethanol.

In order to produce ethanol from starchy materials such as [[cereal grain]]s, the starch must first be broken down into sugars. In brewing [[beer]], this has traditionally been accomplished allowing the grain to germinate, or [[malt]]. In the process of germination, the seed produces [[enzyme]]s that can break its starches into sugars.

Ethanol is also produced by the catalytic hydration of ethylene. Crude oil is catalytically 'cracked' to ethylene and the ethylene is chemically combined with water at high temperatures with an acid catalyst. This process is actually cheaper than fermentation,
but has become less common as ethanol produced from corn is heavily subsidized by the federal government.
==Co-products==

A co-product of the fermentation process is [[distillers grains]] which can be used as cattle feed. Distillers grains is termed either [[wet distillers grains]] or [[dried distillers grains]] or simply [[DDGs]]. Wet distillers grains have a very short shelf life as they are susceptible to microorganisms that can pollute the material and render it unfit for cattle consumption.

==Ethanol Industry==
[[Image:684.jpg|right|thumb|From biomass to ethanol.|400px]]
In the [[United States]] ethanol is most commonly made through the fermentation of corn. Other countries, such as [[Brazil]], use [[sugarcane]] as a [[feedstock]] for the production of ethanol. Currently, the US has the highest production numbers for ethanol in the world, but some analysts forecast China as being a potential world player in the ethanol market. [[China]] currently uses [[casava]] and [[wheat]] among other material for producing ethanol.

==Controversy==

Some in the [[Foot vs. Fuel]] debate consider the use of a high-energy food crop, such as corn, detrimental to our food supply. In particular, [[Lester Brown]] of the [[Earth Policy Institute]] is known for advocating this position.

The latest automotive grade of ethanol in Canada has 1% water. This is specified by the CSB, the Canadian Standards Board. Water is terrible for any fuel injection system and will probably lead to corrosion of the fuel injectors and fuel pumps.

The auto fuel ethanol government standards in Brazil, do not allow any water.

One major gasoline wholesaler and retailer in Canada has used 8% ethanol in all its grades of gasoline for over 10 years because it was one of the cheapest ways to boost the octane rating of gasoline. The R+M rating of ethanol is 104.

Ethanol has about 36% oxygen by weight whereas normal gasoline has no oxygen.
This is why a car runs much smoother at very low temperatures during the first 2 or 3 minutes as the oxygen content in ethanol enhanced gasoline allows a hotter, cleaner burn.

==See also==
*[[Ethenol]]

[[Category:Organic Chemistry]]

Johannes Kepler

2012-09-20T12:13:46Z

Jeepers:

[[Image:Gfdse5y465.jpg|right|thumb|Johannes Kepler]]
'''Johannes Kepler''' (December 27, 1571-November 15, 1630)<ref name=dao>Dao, Christine. "[http://www.icr.org/article/3751/ Man of Science, Man of God: Johann Kepler]." Institute for Creation Research. Accessed March 2, 2008.</ref>, a [[Protestantism|Protestant]] in [[Germany]], was a brilliant mathematician, astronomer, astrologer,<ref>http://www.skyscript.co.uk/kepler.html</ref> and devout [[Christian]] who cited God many times in all of his writings. He felt it was his Christian duty to understand the creation of [[God]] and the universe, and that God had used a mathematical plan for the universe's design.<ref name=dao/> He also felt that man, being in the image of God, was fully capable of understanding the universe. Like [[Plato]] and [[Pythagoras]], Kepler felt that God must have created the universe according to a mathematical plan (see [[Cause of the universe]]).

== Life and career ==
Kepler was born in Weil der Stadt, Württemberg, in what was then known as the [[Holy Roman Empire]], and more particularly in that part of it now known as [[Germany]].<ref name=dao/><ref name=rice>Van Helden, Al. "[http://galileo.rice.edu/sci/kepler.html Johannes Kepler (1571-1630)]." ''The Galileo Project'', Rice University, 1995. Accessed March 2, 2008.</ref><ref name=nasa>"[http://kepler.nasa.gov/johannes/ Johannes Kepler: His Life, His Laws, and Times]." [[NASA]]. Accessed March 2, 2008.</ref> He observed his first [[comet]] at the age of six and his first [[eclipse]] of the [[Moon]] at the age of eight or nine.<ref name=dao/> Kepler overcame an enormous obstacle to become a great scientist, as he suffered from an attack of [[smallpox]] when he was only four years old. The disease left him with poor eyesight and crippled hands for the rest of his life.

Kepler entered the Lutheran seminary at Adelberg in 1584,<ref name=rice/> and in 1589 he won a scholarship to study theology at the University of Tübingen.<ref name=nasa/>

In that era, no serious thinker sought to connect [[astronomy]], a "mathematical" discipline, with [[physics]]. But Kepler sought out his first passion to discover the [[planet]]s' paths, instead of settling for what was assumed. He also came under the influence of [[Michael Maestlin]], who was one of the first astronomers to realize, as had [[Nicolaus Copernicus]], that the [[Earth]] and the other planets revolved around the [[Sun]]. Maestlin taught [[heliocentrism]] only to graduate students, of whom Kepler was one.

Scientists of that time were often opinionated and prone to risk-taking in their theories, and Kepler was no exception. He sacrificed his religious reputation by questioning the "science" of the time, which later forced him to be cut off from orthodox [[Lutheranism]]. Although the loss was great, Kepler was able to become a mathematician and teacher in Graz, [[Austria]], in 1594.<ref name=dao/><ref name=rice/> While at Graz, Kepler wrote his famous ''Mysterium Cosmographicum'', the first forthright and public defense of Copernican [[heliocentrism]].<ref name=nasa/>

In 1600, Kepler left his job at Graz on account of the [[Counter Reformation]]. Unwilling either to convert to Catholicism or to sign the Lutheran Formula of Concord, he decided to leave Graz and travel to Prague.<ref name=nasa/><ref name=rice/> There he became the assistant to [[Tycho Brahe]], court mathematician to Emperor Rudolf II.<ref name=dao/>. Tycho was also makng observations on the orbit of the planets. In 1601, Tycho died, and Kepler was named Imperial Mathematician in his place,<ref name=nasa/> the highest ranking in Europe at the time.<ref name=rice/> After reading and studying the data that Tycho had developed and researched, Kepler was able to resolve a nagging problem concerning the motion of [[Mars]], and in particular its apparent [[retrograde motion]] in relation to the [[Earth]]. Kepler went on to calculate Mars' orbit--as an [[ellipse]], not a [[circle]].

Kepler remained as Imperial Mathematician until 1612, when Rudolf II was deposed.<ref name=rice/> In the next year (1613) he accepted a teaching position in Linz, the last semi-permanent position he ever held. He held this job until 1626, when the pressures of the [[Thirty Years' War]] forced him to leave. Now out of a job and with no salary, he tried in vain to seek employment and to sue for back payment of his salary as Imperial Mathematician.<ref name=rice/> He died in 1630, at Regensburg.<ref name=rice/><ref name=nasa/>

== Kepler's contributions to astronomy ==
From this material Kepler formulated his three [[Kepler's laws of planetary motion|Laws of planetary motion]], his best-known contribution to astronomy. Central to these laws is the insight that celestial bodies travel in [[ellipse|elliptical]] [[orbit]]s. What might not be widely appreciated is that he endeavored to link astronomy with physics.<ref name=dao/> Kepler published his first exposition of his laws, ''Astronomia Nova'', in 1609. Kepler's insights would later help Sir [[Isaac Newton]] formulate his law of [[gravity]].

Very few of his fellow scientists appreciated the link between astronomy and physics. [[Galileo Galilei]], discoverer of the four [[dwarf planet]] sized [[moon]]s of [[Jupiter]], virtually ignored Kepler, as did [[René Descartes]] and even his old mentor Michael Maestlin.<ref name=dao/> But Kepler did not ignore Galileo. He published a lengthy letter of support for Galileo in 1610, after Galileo had published his findings of the [[Galilean moons|Jovian moons]], and in 1611 he published his own detailed observations of those same satellites. He made those observations, accurate to within one-tenth of a degree, once he acquired a suitable telescope.<ref name=rice/>

== Kepler's other contributions ==
In 1613, while at Linz, Kepler published his own calculation of the exact year of the birth of [[Jesus Christ]]. He it was who first concluded that the Julian-Gregorian calendar systems were off by four years, and that Jesus was born in 4 BC (Julian calendar), not AD 1.<ref>James Ussher might have used those calculations in his ''[[The Annals of the World|Annals]]'' to fix the date of Christ's birth and the Crucifixion.</ref> Other tomes to his credit include ''Harmonices Mundi'' (1619, a defense of his Third Law of Planetary Motion) and ''Epitome Astronomiae'' (1621, a systematic defense of heliocentrism in seven volumes).<ref name=nasa/> His last work was the ''Rudolphine Tables'' (named for Rudolf II), a completion of Tycho Brahe's work. In that work he used logarithms, which he developed, to calculate predicted positions of all the planets known to that time. Those tables correctly predicted two solar transits of [[Mercury]] and [[Venus]], events that occurred after his death but on the dates he predicted.<ref name=nasa/>

== Kepler's insights ==

Kepler wrote in book five of his work, ''Harmonices Mundi'':{{cquote|O, Almighty God, I am thinking Thy thoughts after Feet! ... The book is written, to be read either now or by posterity, I care not which. It may be well to wait a century for a reader, as God has waited six thousand years for an observer.}}

Kepler compared the celestial orbits of the planets with polyphonic harmonies in music. He wrote:{{cquote|Holy Father, keep us safe in the concord of our love for one another, that we may be one just as Thou art with Thy Son, Our Lord, and with the Holy Ghost, and just as through the sweetest bonds of harmonies Thou hast made all Thy works one; and that from the bringing of Thy people into concord, the body of Thy Church may be built up in the Earth, as Thou didst erect the heavens themselves out of harmonies.}}

==External Links==
*[http://www.relativitycalculator.com/Kepler_1st_Law.shtml   Johannes Kepler empiricism and mathematics provided the basis for Newton's laws of motion and gravity]
*[http://www.skyscript.co.uk/kepler.html Johannes Kepler and the Music of the Spheres]

== References ==
<references/>

[[Category:Astronomers|Kepler, Johannes]]
[[Category:mathematicians|Kepler, Johannes]]

Star

2012-09-20T12:12:03Z

Jeepers:

[[Image:Moooghj.jpg|300px|right]]'''Stars''' are extremely large, luminous bodies of gas. They are the most obvious features found in the [[universe]]. They are principally composed of [[hydrogen]] that is undergoing nuclear [[fusion]] to become [[helium]]. Our Sun is the nearest star to Earth, at a distance averaging 93 million miles. The Earth orbits the Sun in a period of approximately 365.25 days, and this defines the [[year]]. The diameter of the Sun, which is a typical star, is about 870,000 miles and its power output is about 1026 watts. The temperature inside the Sun is estimated to be in excess of ten million degrees, and this is hot enough for [[nuclear reactions]] to occur.

In Genesis, the stars were made in the fourth day<ref>[Genesis 1-8 (Translated)|Gen 1:14]</ref>, and their number is compared to the number of descendants of Abraham<ref>[Genesis 9-16 (Translated)|Gen 15:5]; an earlier count of the number of descendants of Abraham was the number of grains of dust of the Earth (Gen 13:16)</ref>.

The [[Bible]] implies that the number of stars is virtually countless<ref>[Jeremiah 27-34 (Translated)|Jeremiah 33:22]; similarly to Genesis, the number of descendants of David is compared to the number of stars and the number of grains of sand</ref>, but for many years this was not accepted. [[Hipparchus]] in 128 B.C. stated there were 1,026 stars in the sky. [[Kepler]] in 1600 A.D. did his own count and found the number to be 1,005. Today, thanks to telescopes (especially the [[Hubble Telescope]]) showing many stars previously too dim to be seen, the current estimate is 70,000,000,000,000,000,000,000,000 (7*1025).<ref>[http://www.cnn.com/2003/TECH/space/07/22/stars.survey Star survey reaches 70 sextillion</ref>

==Measuring stellar positions==
=== Distances ===
The oldest method of measuring the distance from our solar system to a distant star is the parallax method. To use this method, astronomers measure the right ascension on the sky of the star at two times of the year, half a year apart. The two measurements will differ by a small angle with respect to the most distant stars in that region of the sky. Exactly half this angle is the ''parallax angle'', having symbol ''p''. This is the angle that the star makes with the [[sun]] and the position of the [[earth]] at a right angle with that star.<ref name=Britannica3>"[http://www.britannica.com/eb/article-52809/star Star: Determining stellar distances]." ''Encyclopædia Britannica''. 2008. Encyclopædia Britannica Online. Accessed 21 Apr. 2008</ref> The distance s of the star, in astronomical units (AU), is:

<math>\,\!s = \cot p</math>

In the range of the very small angles typically encountered, the cotangent of the angle measure (in radians) is very nearly equal to the reciprocal, and thus:

<math>\,\!s \approx \frac {180 \times 3600}{p \times \pi}</math>

where pi is measured in seconds of arc.

The cotangent of one second (1/3600 of a degree) of arc is approximately 206,264.81. No parallax angle for any star will be larger than one second. Therefore astronomers initially defined a unit of stellar distance, the ''parsec'' (symbol pc), from this relationship. One parsec is the distance corresponding to a parallax angle of one second of arc. Hence:

<math>1 pc \approx 206,264.81 AU</math>

However, the error of measurement of parallax angle is 0.005 arc seconds, and beyond a distance of 100 parsecs, this error becomes significant. 700 stars are near enough to measure their distances directly by using parallax.<ref name=Britannica3/> To measure distances further out than this, astronomers typically use absolute and relative magnitudes, or they apply Hubble's Law to the star's estimated [[redshift]].

=== Positions in sky ===
The most common system for describing the position of a star in the sky is the equatorial system. This system uses two coordinates:
# Right ascension on the sky, or the number of hours required for the earth to rotate before an observer can see the star at its highest point in the sky. The zero for right ascension is midnight on the day of the vernal equinox.<ref name=WeissteinRA>Weisstein, Eric W. "[http://scienceworld.wolfram.com/astronomy/RightAscension.html Right Ascension]." ''Eric Weisstein's World of Astronomy'', 2007. Accessed April 21, 2008.</ref>
# Declination, or the north-south angle between the star and the celestial equator.<ref name=WeissteinD>Weisstein, Eric W. "[http://scienceworld.wolfram.com/astronomy/Declination.html Declination]." ''Eric Weisstein's World of Astronomy'', 2007. Accessed April 21, 2008.</ref>

===Proper motion===
All stars move, but the most distant stars are considered "fixed" because their motion would be undetectable. The ''proper motion'' (symbol m) of any star is the angular velocity of its position across the sky. This describes the motion at right angles to the line of sight of the observer. To convert this to actual ''tangential velocity'', multiply the tangent of this angular velocity by the star's distance.

The motion ''in'' line of sight, or ''radial velocity'', is currently determined from spectral shift.

== Measuring stellar magnitudes ==
The visual magnitude system is defined as follows: a star of any given magnitude is about 2.512 times as bright as is a star of the next magnitude. [[Hipparchus]] devised the magnitude system, and [[Ptolemy]] refined it further. By convention, an arbitrary sample of the twenty brightest stars that they could observe were assigned to the first magnitude, and the stars that they could barely observe were assigned to the sixth. Sixth-magnitude stars are actually 100 times less bright than first-magnitude stars. Magnitude levels between these extremes are assigned on a logarithmic scale. Thus, given two stars of brightness l1 and l2, their magnitude difference (V2 - V1) relates to their respective brightnesses in this way:<ref name=Haworth>Haworth, David. "[http://www.stargazing.net/david/constel/magnitude.html Star Magnitudes]." ''[http://www.stargazing.net/david/index.html Observational Astronomy]'', 2003. Accessed April 21, 2008.</ref>

<math>\,\!V_2 - V_1 = 2.5 \times \log \frac{l_1}{l_2}</math>

The ''absolute'' magnitude of any star is the visual magnitude that it would have if it were ten parsecs distant. To convert apparent magnitude V to actual magnitude M, use this formula:

<math>\,\!M = V + 5 \times \log \frac{s_0}{s}</math>

where s0 is the standard distance. This distance is ten parsecs, or about 2,062,650 AU.

Brightness declines with the square of distance, and squares correspond to doubling of logarithms. One must then multiply that result by 2.5 to stay within the magnitude scale.

== Stellar colors and spectra ==
The ''color'' of a star is objectively quantifiable. To determine color, astronomers view the star through a variety of colored filters and compute ''color indices'' as the differences in apparent magnitudes through the various filters. Stellar colors vary, in order from the coolest to the hottest, from red to yellow to white to blue-white to blue or violet. This is the same gamut of colors that a black body shows as its temperature rises.

In addition, each star has a unique ''spectrum'', which depends on the gases and other elements that it contains, and their distribution. A spectrum can serve two purposes:
# It can serve as a unique signature for the star, to distinguish it from other stars.
# It can provide information on the star's radial velocity vis-à-vis the earth.

To accomplish the latter, astronomers note the placement of various lines in the spectrum and then determine the star's likely constituent elements from the spacing of those lines. Lines that are out of ''place'' are shifted, either toward the blue or toward the red. Nearly all stellar spectra are shifted toward the red; this [[redshift]] indicates a recession, either of the star or of the part of space where the star resides.<ref>Some [[cosmology|cosmological]] models call for an expansion of space itself, not merely the matter in it. According to these models, a redshifted star is in a part of space that was still expanding as the incident light was generated.</ref>

=== Spectral Type ===
[[Image:Hertzsprung-Russell.jpg|thumb|300px|right|Hertzsprung-Russell Diagram]]
In the late nineteenth century, astronomers at the [[Harvard University]] observatory developed the first classification scheme for stellar spectra that would become known as the '''Harvard spectral classification'''. In 1924, Annie Jump Cannon<ref name=Cannon>"[http://imagine.gsfc.nasa.gov/docs/teachers/lifecycles/LC_main_p8.html Life Cycles of Stars]." ''Goddard Space Flight Center'', November 21, 2002. Accessed April 22, 2008.</ref> refined the classification from the original A-Q gamut to the familiar "OBAFGKM" gamut. Astronomers have since added classes to this range at the high end and the low.<ref name=Swinburne>"[http://astronomy.swin.edu.au/cosmos/H/Harvard+Spectral+Classification Harvard Spectral Classification]." ''Study Astronomy Online at Swinburne University''. Accessed April 22, 2008.</ref><ref name=Seattle>Irizarry, David. "[http://www.seattleastro.org/webfoot/feb00/pg2.htm The Secrets of the Harvard Classification Revealed]." ''The Webfooted Astronomer'', Seattle Astronomical Society, February 2000. Accessed April 22, 2008.</ref>

The classic Harvard spectral classes are O, B, A, F, G, K, and M. Each of these has ten subclasses, varying from 0 to 9 in order of decreasing stellar temperature. Thus, for example, the next class after an F9 star is a G0 star. Recently astronomers recognized one class of stars hotter than the O stars (the very hot Wolf-Rayet stars) and three classes of stars (the N, R, and S stars) cooler than the M stars. (Some astronomers include the N and R stars in one class, the C stars, for the carbon compounds that their spectra exhibit). There is an additional spectral class for the smallest and dimmest stars (Class L), that still fuse hydrogen, although warmer [[brown dwarf|brown dwarfs]] also fall into this class (but referred to as L dwarfs instead of L stars). Cooler still methane dwarfs are classified as [[Brown_dwarf#Spectral_class_T|T dwarfs]].<ref>http://adsabs.harvard.edu/abs/2007arXiv0704.1522K</ref> A proposed spectral class Y has been suggested for the coolest brown dwarfs, which also have a different spectra from T class dwarfs.<ref>http://xxx.lanl.gov/abs/astro-ph/0607305</ref>

{| class="wikitable"
|-
! Class
! [[Temperature]]
! Color
! [[Element]]s
! Notes
|-
| W
| 106,000 K
| Violet
| Ionized [[helium]], [[carbon]], [[oxygen]], [[nitrogen]]
| Wolf-Rayet stars. Additional subclasses include WC (overabundant carbon and oxygen) and WN (overabundant nitrogen)
|-
| O
| 30,000 K
| Blue
| Ionized [[Helium]], [[nitrogen]], [[oxygen]]
| Weak Balmer lines ([[hydrogen]]) at higher subclasses.
|-
| B
| 13,000 K to 20,000 K
| Blue
| Neutral helium; ionized [[silicon]], oxygen and [[magnesium]].
| [[Hydrogen]] (Balmer lines) appear in strength
|-
| A
| 75,00 to 10,000 K
| Blue-white
| [[Hydrogen]], [[calcium]], [[helium]]
| Balmer lines dominant. K lines (calcium) now appearing.
|-
| F
| 7,000K to 9,000K
| White-yellow
| [[Hydrogen]], [[calcium]], [[iron]], [[manganese]], [[sodium]]
| Balmer lines weakening. K lines stronger.
|-
| G
| 5,200 to 6,000K
| Yellow
| [[Calcium]], [[hydrogen]], other [[metal]]s
| Balmer lines weaker still. K lines dominant. Metals now appearing.
|-
| K
| 4000K to 5100K
| Orange
| [[Calcium]], neutral metals, [[titanium oxide]]
|
|-
| M
| 3000K
| Red
| [[Titanium oxide]], [[iron iodide]]
| Strong molecular bands
|-
| N,R
| 2300K to 2600K
| Red
| [[Carbon]] compounds
|
|-
| S
| 2300K to 2600K
| Red
| [[Hydrogen]], [[zirconium oxide]]
|
|}

In the early twentieth century, astronomers Ejnar Hertzsprung and Henry Norris Russell prepared the first plot of stellar temperature as a function of luminosity, or brightness. Other astronomers have since prepared versions of the diagram showing absolute magnitude as a function of color. This diagram shows a "main sequence" of stars for which brightness declines as temperature increases, but also shows a "white dwarf" population of very hot but dim stars, and the population of giants and supergiants that are far brighter than their temperatures would indicate.<ref name=HR>"[http://astronomy.swin.edu.au/cosmos/H/Hertzsprung-Russell+Diagram Hertzsprung-Russell Diagram]." ''Study Astronomy Online at Swinburne University''. Accessed April 22, 2008.</ref>

===Luminosity Class===

In addition to the spectral type, astronomers today add a ''luminosity class'', which varies from 0 to VII in order of decreasing brightness. This is known as the '''Yerkes spectral classification'''. This classification was first developed by astronomers William Wilson Morgan, Phillip C. Keenan and Edith Kellman at the [[Yerkes Observatory]] in 1943.<ref>Morgan, William Wilson; Keenan, Philip Childs; Kellman, Edith (1943), "An atlas of stellar spectra, with an outline of spectral classification", Chicago, Ill., The University of Chicago press</ref> Adding a luminosity classification added a second dimension to the single dimensional [[Harvard University|Harvard]] spectral sequence. Today the two classifications of temperature and luminosity is used to give the spectral sequence for a star.<ref>http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?bibcode=1973ARA%26A..11...29M&db_key=AST&data_type=HTML&format=&high=449aa1cc7c02014</ref> For example, the [[sun]]'s spectral type is G2 and its luminosity class is V (five).

{| class="wikitable"
|-
! Luminosity Class
! Star Type
|-
| 0 - 0Ia - Ia0
| hypergiants
|-
| Ia - Iab - Ib
| [[Supergiant|supergiants]]
|-
| IIa - IIab - IIb
| bright giants
|-
| IIIa - IIIab - IIIb
| giants
|-
| IVa - IVab - IVb
| subgiants
|-
| Va - Vab - Vb
| main sequence stars (dwarfs)
|-
| VI
| subdwarfs
|-
| VII
| [[white dwarf|white dwarfs]]
|}

==Variable stars==

Some stars vary in brightness and are known as variable stars. The star [[Algol]] in the constellation of Perseus can drop from its normal magnitude of 2.3 to magnitude 3.5. This is now known to be caused by a dim companion star orbiting Algol, which occasionally passes between Algol and the Earth, blocking some of the light. Other variable stars vary in brightness due to actual variations in the luminosity of the star itself. The time taken from one maximum brightness to the next one is called the '''period'''. The most famous of the variable stars is delta Cepheus, the first-found member of the [[Cepheid]] group of variable stars. In 1908 [[Henrietta Swan Leavitt]] noticed that the variable stars in the [[Magellenic Clouds]] (two nearby galaxies in the [[Local Group]]) had a relationship between their period and their apparent brightness. At that time galaxies outside our own (the [[Milky Way]]) had been discovered, but it was not possible to measure the distances to them. It was soon realized that the variable stars in the Magellenic Cloud were of the Cepheid type. Since Cepheid variables also occur in our [[galaxy]] it was possible measure their distances and thus convert (using the inverse square law) Leavitt's relationship between apparent brightness and period to one of actual brightness and period. Once this formula was discovered, it became possible to apply to Cepheids of unknown distance. By observing their periods, their actual brightness can be calculated and, by the inverse square law, their distance. Through observations of Cepheids in [[globular cluster]]s (compact bunches of stars) in our galaxy it was shown that our galaxy is about 300,000 light-years in diameter.

== Energy production ==
[[Image:CNO_Cycle.png|300px|thumb|CNO cycle]]The [[Sun]], and stars as massive as the Sun or less massive, commonly use a [[nuclear fusion]] process called the '''proton-proton chain reaction''' to produce [[energy]]. A full description of that process appears [[Sun#Energy production and transport|here]].

In 1938 and 1989, two physicists, Carl F. von Weizsäcker<ref name=Weiz>Von Weizsäcker, Carl F. ''Physik. Zeitsch.'' 39:633, 1938.</ref> and Hans Bethe<ref name=Bethe>Bethe, Hans A. "[http://prola.aps.org/abstract/PR/v55/i5/p434_1 Energy Production in Stars]." ''Physics Review'' 55(5):434-456, 1939. {{doi|10.1103/PhysRev.55.434}} Accessed June 27, 2008.</ref> independently proposed a [[nuclear fusion]] process, the '''Carbon-Nitrogen-Oxygen cycle''', by which stars more massive than the [[sun]] produce energy. In this process, stars convert [[hydrogen]] to [[helium]] using [[carbon]], [[nitrogen]], and [[oxygen]] as catalysts. The reaction also produces two [[positron]]s and two [[electron neutrino]]s.<ref name=Krane>Krane, Kenneth S. ''Introductory Nuclear Physics''. New York: John Wiley and Sons, 1988, p. 537. ISBN 9780471805533</ref>

The equations for the cycle are as follows:

<math>{}^{12}_6\!\mbox{C} + {}^1_1\!\mbox{H} \to {}^{13}_7\!\mbox{N} + \gamma + \mbox{1.95 MeV}</math>

<math>{}^{13}_7\!\mbox{N} \to {}^{13}_6\!\mbox{C} + {}^0_1\!e^+ + {}^0_0\!\nu_e + \mbox{2.22 MeV}</math>

<math>{}^{13}_6\!\mbox{C} + {}^1_1\!\mbox{H} \to {}^{14}_7\!\mbox{N} + \gamma + \mbox{7.54 MeV}</math>

<math>{}^{14}_7\!\mbox{N} + {}^1_1\!\mbox{H} \to {}^{15}_8\!\mbox{O} + \gamma + \mbox{7.35 MeV}</math>

<math>{}^{15}_8\!\mbox{O} \to {}^{15}_7\!\mbox{N} + {}^0_1\!e^+ + {}^0_0\!\nu_e + \mbox{2.75 MeV}</math>

<math>{}^{15}_7\!\mbox{N} + {}^1_1\!\mbox{H} \to {}^{12}_6\!\mbox{C} + {}^4_2\!\mbox{He} + \mbox{4.96 MeV}</math>

The last reaction reproduces the <math>{}^{12}_6\!\mbox{C}</math> nucleus that the first reaction consumes. The end result of this process is:

<math>\mbox{4} {}^1_1\!\mbox{H} \to {}^4_2\!\mbox{He} + \mbox{2} {}^0_1\!e^+ + \mbox{2} {}^0_0\!\nu_e + \mbox{3} \gamma + \mbox{26.8 MeV}</math>

Rarely, this cycle branches into a somewhat different cycle involving [[fluorine]], and that second cycle is thought to branch again in some of the most massive stars.

==Origins==
Christian scientists assert that [[materialism|materialistic]] explanations of the origin of stars are errant and contra-evidence and reports of stars forming are invalid. <ref>http://www.icr.org/article/403/</ref><ref>http://www.answersingenesis.org/creation/v18/i2/stars.asp</ref><ref>http://www.creationscience.com/onlinebook/AstroPhysicalSciences21.html</ref><ref>http://www.answersingenesis.org/Docs/399.asp#55</ref><ref>http://www.answersingenesis.org/creation/v19/i1/feedback.asp</ref> In addition, creationists cite the secular scientific literature in order to make the case that materialist explanations of star formation are inadequate:

“We don’t understand how a single star forms, yet we want to understand how 10 billion stars form.” Carlos Frenk, as quoted by Robert Irion, “Surveys Scour the Cosmic Deep,” Science, Vol. 303, 19 March 2004, p. 1750. <ref>http://www.sciencemag.org/cgi/content/summary/303/5665/1750</ref>

“Nobody really understands how star formation proceeds. It’s really remarkable.” Rogier A. Windhorst, as quoted by Corey S. Powell, “A Matter of Timing,” Scientific American, Vol. 267, October 1992, p. 30. <ref>http://adsabs.harvard.edu/abs/1992SciAm.267Q..26P</ref>

==References==
<references/>

==Other References==
The ''Observer's Book of Astronomy'', by Patrick Moore. Published by Frederick Warne and Co. 1967.

The ''Cosmological Distance Ladder'', by Michael Rowan-Robinson. Published by Freeman. 1985.

[[category:astronomy]]

The Crusades

2012-09-20T12:09:46Z

Jeepers:

{{Middle Ages}}

[[Image:Crusader.jpg|thumb|200px|right|A returning Crusader]]
'''The Crusades''' (1095-1291) were a series of European Christian campaigns into the Middle East, fought during the middle ages. They were the military responses made by Christians from western Europe to the Pope's pleas to re-capture the Holy Land from Islamic influence. The '''First Crusade''' created new Latin states in the Holy Land. Subsequent crusades were less successful except when they attacked Byzantium. Other medieval movements against heretics and infidels were also called crusades. The crusades ended with the Islamic recapture of all the Holy Land in 1291, when the the last city controlled by crusaders, Acre, fell.

The crusades comprise a major chapter of [[Middle Ages|Medieval History]]. Extending over three centuries, they attracted every social class in western Europe. Kings and commoners, barons and bishops, knights and commoners—even teenagers—all participated in these expeditions to the eastern end of the Mediterranean. The motives of the crusaders were numerous: some sought riches; many sought adventure; most were moved by faith alone. Historians stress the central role of religious fervor, while mentioning as well the socio-economic factors crucial in enticing larger contingents. For example, crusaders often were fulfilling their feudal obligations. There were strong links between the papal reforms, the social necessity of violence and the exploitation of this inherent revivalistic imagination of the age of the Papacy.<ref> Douglas James, "Christians and the First Crusade," ''History Review,'' (Dec 2005), Issue 53</ref>

The crusades failed to achieve the permanent control of the Holy Land. However, their influence was wide and deep. Much of
the crusading fervor carried over to the successful fights against the Moors (Muslims) in Spain and the pagan Slavs in eastern Europe. Politically the crusades weakened the decrepit Byzantine Empire, but temporarily kept the Muslims away from it. The First Crusade strengthened the moral leadership of the
papacy in Europe, but the failures of the later crusades weakened both the crusading ideal and respect for the papacy
Contact with the East widened the scope of the Europeans, ended their isolation, and exposed them to an rich civilization. The economic effects of the crusades were modest, but they did reopen of the eastern Mediterranean to Western commerce, which itself had an effect on the rise of great cities such as Venice and the emergence of a money economy in the West.

The crusaders derived their name from the Latin word for "cross"--crux. A crusader went to the Holy Land with a cross of cloth sewn over his breast; when he returned, he had a similar cross for his back. Originally called to repel the Islamic forces that controlled [[Jerusalem]], the crusades evolved into a form of political decree called by the Papacy for political, social or economic reasons. The campaigns of [[Teutonic knight]]s against [[pagan]] strongholds in [[Eastern Europe]] are also sometimes called crusades. Lastly, military actions within Christendom against heretical and schismatic groups are sometimes called a crusade. Thus a crusade in most general terms was a directive of war issued by the Pope to all Rome-friendly nations against forces, whether Muslim, pagan or Eastern Orthodox, which were hostile to the Papacy.

The crusades in the Holy Land ultimately failed to establish permanent Christian kingdoms. The fourth crusade resulted in a very damaged relationship between [[Orthodox Church|Greek]] and [[Roman Catholic|Latin]] Christendom. Islamic expansion into remained a threat for centuries, with crusading orders establishing strongholds to protect Mediterranean islands.

On the other hand, the crusades in southern [[Spain]] were militarily successful, eventually leading to the end of Islamic power in the region in 1492. The Teutonic knights expanded Christian domains in Eastern Europe, and the [[Albigensian Crusade]], achieved its goal of destroying heretics in France. <ref>See Brian Tierney and Sidney Painter, ''Western Europe in the Middle Ages 300–1475''. 6th ed. (McGraw-Hill 1998)</ref>

== Need for a crusade ==
The Holy Land had been part of the [[Roman Empire]], and thus the [[Byzantine Empire]], until the Islamic conquests of the seventh and eighth centuries that forced the Byzantines out and saw the area gradually turn Islamic. Calm returned and Christians had generally been permitted to visit the sacred places in the Holy Land until 1071, when the [[Seljuk Turks]] assailed the Byzantines, defeating them at the [[Battle of Manzikert]], and conquered Jerusalem from the Egyptian Fatimids the same year. They were not friendly to Christian pilgrims, in contrast to how the Fatimids had been, and soon pilgrims came under threat of robbery or even death as they were no longer welcome. The Byzantine Emperor [[Alexius I]] asked for aid from the west both to the Popes and the Christian monarchs. Nothing meaningful happened. Alexius may have been hoping for money from the Pope for the hiring of mercenaries.
==Papal call==
Pope Urban II called upon the knights of Christendom to fight for the defense of the Christian East and the protection of pilgrims in a speech made at the [[Council of Clermont]] on November 27, 1095. Urban demanded that all internal feuds within Christendom end, threatening [[excommunication]] for anyone who continued to bicker internally, and promising absolution and assurance of salvation to anyone who died in the crusade.

This time Europe listened. Those who were there erupted in spontaneous cries of "Deus le vult!" ("God wills it!") - which would become the watchword of what we now know as the Crusades.

Nothing like this had ever been done, and the Pope himself had no military power and had to count on those who were in positions of power to supply it. While the monarchs of Europe did not get directly involved, it was a series of prominent nobles who answered the call, among the most famous being: the Norman Bohemund of Taranto, former claimant to the Duchy of Apulia, his nephew Tancred, Count Raymond of Toulouse, [[Godfrey Of Bouillon|Duke Godfrey de Bouillon]] of Lorraine, Duke Hugh of Vermandois (brother of the King of France), Duke Robert of Normandy, and Count Robert of Flanders. The spiritual leader who accompanied them was French Bishop Adhemar du Puy, who was appointed Papal legate.

All that was known at the start was that the forces to participate would meet together in [[Constantinople]], where Alexius had no idea what was being unleashed.

== The First Crusade ==
The [[First Crusade]], properly speaking, was lead by Feudal lords, mostly of [[Franks|Frankish]] origin. Many of the knights left home never expecting to return, knowing virtually nothing about the [[Holy Land]], and trusting in God for victory. The army consisted of almost 20,000 men, including a mass of [[squire]]s and other servants necessary to support a mounted knight. Arriving at Constantinople the force, which eventually reached almost 50,000 total men, was not what the Byzantine Emperor [[Alexius]] had expected. He had hoped for a few thousand well trained mercenaries to help him retake his lands from the Turks, and had little in common with the goal of 'freeing the Holy Land'. An uneasy tension ensued from 1096 to 1097 as the forces gathered, but through a combination of firmness and diplomacy, Alexius avoided serious complications. In return for his assurance of assistance, he obtained oaths of allegiance from the Crusader leaders, and their promise that they would help recapture [[Nicaea]] from the Turks and return to him any other former possessions which they conquered. Alexius then transported them across the Bosporus - being careful not to allow any large number of Crusader forces inside the walls of his capital at any given time. He also provided them with food and with an escort of Byzantine troops to guide them towards their objectives (and incidentally to prevent Crusader plundering).<ref>Encyclopedia of Military History, Dupuy & Dupuy, 1979, Pg. 312-313</ref>

After a hard march to the Holy Land, the army captured invested Nicaea in 1097. By a combination of skillful fighting and skillful diplomacy, Alexius arrange for the surrender of the city to him after a successful Crusader-Byzantine assault on the outer walls. The Crusaders were upset at Alexius' refusal to give them permission to sack the city.

The Crusaders continued to the southeast in parallel columns, without any one commander in charge. After fighting the inconclusive [[Battle of Dorylaeum]], the army split in half. Tancred and Baldwin, brother of Godfrey of Lorraine and future King of Jerusalem, went east took the Armenian fortress-city of [[Edessa]] - an action that destroyed the support of many local Armenian Christians for the Crusade, and weakened its internal bonds, as Baldwin and Tancred's men clashed over possession of the city, with Baldwin emerging triumphant. The main body of the army continued onward and besieged [[Antioch]]. The city was surrounded for 8 months from October 21, 1097 to June 3, 1098. Two relieving armies were driven off in the [[Battles of Harenc]] in December and February. Due to poor arrangements for supplies, the Crusading army was actually close to starvation, but was saved by the fortuitous arrival of English and Pisan flotillas which seized two nearby ports and brought provisions. Bickering among the Crusader leaders, especially [[Bohemund]] and [[Raymond]] was rampant. The initiative of Bohemund led to the capture of Antioch just 2 days before a relieving army of 75,000 strong under the atabeg of Mosul, [[Kerboga]] would arrived, delayed itself after a fruitless three-week long attempt to dislodge Baldwin from Edessa.

Now it was the Crusaders turn to be trapped inside the city as Kerboga sieged Antioch from June 5, to June 28, 1098. The Crusaders were cut off from supplies and again near starvation. A Byzantine army was coming to take the city as agreed, but hearing that the Crusaders were doomed, turned back to Constantinople. It was then the 'Holy Lance' was discovered; the weapon said to have pierced Jesus' side. While few historians or theologians believe this miraculous discovery was valid, it energized the Crusader army at just the time they needed it. The [[Battle of the Orontes]] was fought on June 28 where 15,000 Crusaders left Antioch to battle and drove off the entire Moslem army and broke the siege, helped in part by the decision of several of the local emirs serving under Kerbogha to abandon him during the battle, fearing that he coveted their territory.

Due to internal bickering, many of the Crusaders did not continue on to [[Jerusalem]]. The force that arrived in June 1099 was only about 12,000 strong, far fewer than the army of defenders. They sieged the city from June 9 to July 18. Realizing they didn't have enough men to keep out supplies and starve the defenders, they boldly attacked. Overrunning the city, many of the inhabitants were massacred, including other Christians. A relieving force of 50,000 strong arrived in August to fight the Crusaders, but were routed at the [[Battle of Ascalon]]. The military aspects of the First Crusade had ended.

Four feudal kingdoms were established, which would remain for nearly 100 years. Several Military Orders, consisting of [[paladin]]s, were also set up within the next few years, focusing mainly around the protection of the welfare of pilgrims and the defense of Christendom within the framework of an organization that was both spiritual and martial in nature. The best known of these orders were the Knights of the Temple, or [[Templars]], and the Knights of the Hospital of St. John, or [[Hospitallers]]. The Hospitallers still exist today in the form of the Order of Malta and St. John's Ambulance.

== The Second Crusade ==
The [[Second Crusade]] occurred in 1145 when [[Edessa]] was retaken by Islamic forces. It was ultimately a failure, owing in part to the French king's insistence on betraying and attacking his only Muslim ally, [[Damascus]]. In 1187 the Muslims
captured Jerusalem under their leader [[Saladin]], which brought about a new call for a Crusade.

== The Third Crusade ==
[[File:Saladin2.jpg|thumb|left|270px]]The [[Third Crusade]] (1189-92) is famous for the battles between [[Richard I|Richard the Lionheart]] and [[Saladin]], highlighted by the deep respect the two enemies had for each other, and the sense of [[chivalry|chivalric]] honor of King Richard. The crusade also involved the king of France (who returned home after an argument with Richard at Acre) and the Holy Roman Emperor (who drowned en route). The crusade had the limited success of obtaining a truce between Richard and Saladin that promised to allow Christian pilgrimage to Jerusalem.

== The Fourth Crusade ==
The [[Fourth Crusade]], begun by [[Innocent III]] in 1202, intended to retake the Holy Land but was soon subverted by [[Venetian]]s who used the forces to sack the Christian city of [[Zara]]. Innocent excommunicated the Venetians and crusaders. Eventually the crusaders arrived in [[Constantinople]], but due to strife which arose between them and the [[Byzantines]], rather than proceed to the Holy Land the crusaders instead sacked Constantinople and other parts of [[Asia Minor]] effectively establishing the Latin Empire of Constantinople in [[Greece]] and Asia Minor . Both Zara and Constantinople were Christian cities, and the ultimate effect was a severely damaged relationship between Greek and Latin Christendom.

This was effectively the last crusade sponsored by the papacy; later crusades were sponsored by individuals.

==Minor Crusades==
In addition to the four main crusades there were several minor ones.
===The People's (Peasants') Crusade (1095-96)===
As soon as the Pope issued his appeal in 1095 preachers like Peter the Hermit and Walter the Penniless fanned out across Western Europe, reaching pious common people in rural areas, including many peasants. They aroused such an enthusiasm among the peasants that neither the secular lords nor the local clergy could stop the people from marching east, filled with hopes for freedom from serfdom and the zest for adventure. Thousands of peasants set off with few supplies or weapons and no money, and no idea of the enormous distance to be traveled. They believed that God would provide the guidance for direction and the sustenance for life. More prosperous farmers and burghers were also involved. Five uncoordinated bands trekked across the Balkan region toward Constantinople. The Byzantine Christians welcomed them reluctantly and even contemptuously, for the pilgrims robbed them and raided their farms and villages. The Byzantine army fought them in pitched battles; most peasants never reached Constantinople. The thousands who did arrive were militarily useless and unwelcome. The Emperor Alexius temporarily fed and housed them outside the city, then hurried them across the Bosporus into Asia Minor. There the peasants were all killed by the Turkish forces.<ref> Sir Steven Runciman, "The First Crusade: Constantinople to Antioch," in M. W. Baldwin, ed. ''The first hundred years'' (1969) pp. 281-85 [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=turn&entity=History.CrusOne.p0313&isize=M online edition];
Frederic Duncalf, "The Peasants' Crusade," ''The American Historical Review,'' Vol. 26, No. 3 (Apr., 1921), pp. 440-453 [http://links.jstor.org/sici?sici=0002-8762(192104)26%3A3%3C440%3ATPC%3E2.0.CO%3B2-P in JSTOR]</ref>

====Attacking Jews====
A smaller group of peasants led by Gottschalk took out their fervor on a more local target, the Jewish communities of Lotharingia. Their actions were condemned by the Church and the local populace.<ref>The Age of Faith, Will Durant, 1950, Pg. 589</ref><ref name="RS">Riley-Smith, Jonathan. ''The Crusades: a History.'' (2005) </ref> A much larger threat against Jews took the form of a larger mob led by Count Emico of Leiningen, who was more organized and more brutal. Already a man with a sullied reputation, he ignored the pleas of the Bishops in town after town to desist. Apart from being hidden by the local populace when they heard Emico was coming, there was little the Jews could do. Previously in Europe, local difficulties against Jewish communities would rise from time to time in various places, but would be isolated to that local area. This started a phase not previously seen, a systematic effort to weed out and attack Jewish communities.

===The Children's Crusade (1212)===
Even more [[pathetic]] than the peasant crusade of 1095-96 was a movement in France and Germany which attracted large numbers of peasant teenagers and young people (few were under age 15). They were convinced they could succeed where older and more sinful crusaders had failed: the miraculous power of their faith would triumph where the force of arms had not. Many parish priests and parents encouraged such religious fervor and urged them on. The Pope and bishops opposed the the attempt but failed to stop it entirely. A band of several thousand youth and young men led by a German named Nicholas set out for Italy. About a third survived the march over the Alps and got as far as Genoa; another group came to Marseilles. The luckier ones eventually managed to get safely home, but many others were sold as lifetime slaves on the auction blocks of Marseilles slave dealers.<ref>Dana C. Munro, "The Children's Crusade," ''The American Historical Review,'' Vol. 19, No. 3 (Apr., 1914), pp. 516-524 [http://links.jstor.org/sici?sici=0002-8762(191404)19%3A3%3C516%3ATCC%3E2.0.CO%3B2-C in JSTOR]; and Norman P. Zacour, "The Children's Crusade," in R. L. Wolff, and H. W. Hazard, eds., ''The later Crusades, 1189-1311'' (1969) pp. 325-342, esp. 330-37 [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=article&did=HISTORY.CRUSTWO.I0023&isize=M online edition] </ref>

===The Fifth Crusade (1217-1221)===
Instigated by Pope Innocent III in 1215, this crusade was led in 1217 by John Brienne, king of Jerusalem, with the object of conquering Egypt. In 1219 the crusaders captured Damietta. The sultan of Egypt offered to exchange Jerusalem for Damietta but this was rejected. After an unsuccessful assault on Cairo in 1221, the defeated crusaders surrendered Damietta in return for the freedom to retreat.<ref> Thomas C. Van Cleve, "The Fifth Crusade," in R. L. Wolff, and H. W. Hazard, eds., ''The later Crusades, 1189-1311'' (1969) pp. 377-428 [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=goto&id=History.CrusTwo&isize=M&page=377 online edition]</ref>
===The Sixth Crusade (1228-1229)===
The sixth or " Diplomatic Crusade" was led by Emperor Frederick II of the Holy Roman Empire. He began in 1228, but fought no battles. Instead, by negotiation he obtained Jerusalem and a strip of territory from Acre to Jerusalem for the Christians. In 1225 he married Yolanda, the young heiress to the kingdom of Jerusalem; upon her death in 1228, Frederick crowned himself king of Jerusalem.

===The Seventh Crusade (1248-1250)===
Led by King Louis IX of France (reigned. 1226-1270) and directed against the Arabs of Egypt, this crusade was a complete failure. The crusaders were decisively defeated en-route to Cairo and King Louis was captured; the Arabs demanded and received a huge ransom for the release of the hapless king.<ref> Joseph R. Strayer, "The Crusades of Louis IX," in R. L. Wolff and H. W. Hazard, eds., ''The later Crusades, 1189-1311'' (1969) pp. 487-521 [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=goto&id=History.CrusTwo&isize=M&submit=Go+to+page&page=487 online edition]; Peter Jackson, ''The Seventh Crusade, 1244-1254'' (2007) [http://www.amazon.com/Seventh-Crusade-12441254-Texts-Translation/dp/0754657221/ref=sr_1_5?ie=UTF8&s=books&qid=1205399558&sr=8-5 excerpt and text search]</ref>
===The Eighth Crusade (1270)===
Ignoring his advisers, King Louis IX again attacked the Arabs in Tunis in North Africa. He picked the hottest season of the year for campaigning and his army was devastated by disease. The king himself died, ending the last major attempt to free the Holy Land.<ref> Joseph R. Strayer, "The Crusades of Louis IX," in R. L. Wolff and H. W. Hazard, eds., ''The later Crusades, 1189-1311'' (1969) pp. 487-521 [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=goto&id=History.CrusTwo&isize=M&submit=Go+to+page&page=487 online edition]</ref>

===Other Medieval Crusades===
At the time people used "crusade" to describe other religious wars waged against heretics, such as Hussites and Albigensian, as well as Moors in Spain and pagans in the Baltic region.
====The Albigensian Crusade (13th century)====
Pope Innocent III in 1209 called for a war against the Albigensians, a religious sect which had sprung up in southern France, centered near the cities of Albi and Toulouse in Provence.<ref> Essentially, the Albigensians believed in a non-Christian dualist doctrine: there was a coexistence, they affirmed, between good and evil, represented by such opposites as God and the Evil One, light and darkness, soul and body, afterlife and earthly life.</ref> A bloody series of campaigns ended with Provence in ruins (1229) and the heretics defeated. In 1233 Pope Gregory IX placed the Dominicans in charge of investigating the remnants of Albigensianism with the legal power to name and condemn any surviving heretics. This marked the start of the [[Inquisition]].
====Teutonic Knights (1229-1525)====
A German religious and military order originally founded during the siege of Acre in the Third Crusade and modeled after the Knights Templars and Hospitalers, the Teutonic Knights moved to eastern Europe early in the 13th century.<ref>Charles Moeller, "Teutonic Order," [http://www.newadvent.org/cathen/14541b.htm ''Catholic Encyclopedia'' (1912) vol 14 online]</ref> There, under their grand master, Hermann von Salza, they became powerful and prominent. In 1229, responding to an appeal from the [[Poland, history|Duke of Poland]], they began a crusade against the pagan Slavs of Prussia. They became sovereigns over lands they conquered over the next century. In a series of campaigns, the Teutonic Knights gained control over the whole Baltic coast, founding numerous towns and fortresses and establishing Christianity.<ref> Edgar N. Johnson, "The German Crusade on the Baltic," in [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=article&did=HISTORY.CRUSTHREE.I0028&isize=M H. W. Hazard, ed. ''The fourteenth and fifteenth centuries''] (1975) pp 545-85</ref>
===Crusades in Spain (711-1492)===
Muslims crossed from Africa into Spain early in the eighth century and in 711 at the battle of Río Barbate, they defeated the Visigoths and pressed forward to capture Toledo. By 718, the Moors (the name given North African Muslims by the Spaniards) had completed their conquest of the Iberian Peninsula, except for small Christian remnants in the Pyrenees. They remained on for the next 674 years until driven out by Spanish and Portuguese Christians.

The period of the Spanish Crusades began in the eleventh century when a religious revival was initiated by Cluniac monks in the small kingdoms in the north of Spain, which had recovered some of their lost territory. The revival expressed itself in a growing hatred for the infidel. Slowly yet steadily, at first sparked mainly by Burgundians and Normans from France, the Christians began to force the Moors out of northern and central Spain. Known as the [[Wars of the Reconquest]], these centuries-long conflicts intensified the Catholic sentiments of the people, developing an intense, even fanatical unity of religion and patriotism which was long characteristic of the Spaniards.

By the middle of the 15th century, the last bastion of Moorish power on the peninsula was the kingdom of Granada in southwestern Spain. When the marriage of Isabella, Queen of Castile, to Ferdinand, Prince of Aragon, in 1469 united Spain, they vigorously began their last campaign against the Moors. In January 1492 the Spanish entered the city of Granada and Moorish power ended in Europe. The expulsion of the Moors from Spain may be considered the last of the many medieval crusades.<ref> Charles Julian Bishko, "The Spanish and Portuguese Reconquest, 1095-1492" in [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=goto&id=History.CrusThree&isize=M&page=396 H. W. Hazard, ed. ''The fourteenth and fifteenth centuries''] (1975) pp 396-456</ref>

==Long-term Impact==
Thus, though Jerusalem was held for nearly a century and other strongholds in the Near East would remain in Christian possession much longer, the crusades in the Holy Land ultimately failed to establish permanent Christian kingdoms. Islamic expansion into Europe, while temporarily stalled, would renew and remain a threat for centuries with the disintegration of the [[Byzantine Empire]] and culminate with the campaigns of [[Suleiman the Magnificent]] in the sixteenth century.

While the crusades achieved only temporary military success, they had a powerful impact on western Europe. The crusaders returned with a vastly widened knowledge of the world they lived in, and a willingness to explore that became a permanent part of the west European mindset. In religion, culture, and commerce, post-Crusades Europe was visibly affected by its prolonged encounter with another continent and another way of life.

===Commerce and economy===
The merchants of Venice and other Italian cities gained the most profit. They amassed considerable income in payment for the services they rendered the crusaders and were enriched by the commercial rights they obtained throughout the Near East. Genoa, Pisa, and Venice gained special monopolies throughout the eastern Mediterranean. Their merchants used these privileges to introduce into the Western world such oriental luxuries as silks, spices, and pearls, whose transportation and sale made the cities rich. The demand for these products encouraged explorers to seek out new and more direct routes to the East--most famously in the discovery and exploration of the Americas by Columbus and others starting in 1492. The crusades helped create a moneyed aristocracy and encouraged the growth of capitalism in the Italian cities. Silks and spices not only raised the standard of living of the rich, they stimulated the entire urban economy, although cities remained small.

The returning crusaders came back to Europe with new tastes in dress and diet, such as peaches and spinach. They gave up the custom of wearing a load of heavy armor at nearly all times and appeared in the flowing robes of silk or cotton which were the traditional habit of the Muslims.
===Weakens feudalism===
In rural areas, where the vast majority of Europeans lives, the crusades tended to weaken feudalism and strengthen central governments. Thousands of feudal aristocrats died young and many baronial families lost heavily or even went bankrupt because they borrowed money for the adventure and could not repay. Since credit markets were undeveloped and inefficient, the crusaders paid high premiums to borrow; many accepted donations from friends and family. For a local baron to bring along 10 knights on a crusade cost some 3000 livres a year. There was some plunder along the way, but plunder was hard to liquefy to pay off loans back home. Instead of acquiring new rich new lands and fabulous wealth in the East, many noble families sold, pawned or mortgaged lands, castles, benefices, and jewels; most saw their finances damaged. Money lenders in Italian cities grew rich. The feudal barons were the basis of localism; power now tended to become more centralized and national. Of course when the kings crusaded, it cost them dearly and weakened their throne. [[Richard the Lionhearted]] of England sold off the income he was owed from Scotland, and tried to sell London itself but could not find a buyer. By contributing to the rise of the cities, the development of a money economy, and the strengthening of national monarchies, hastened, to some extent, feudalism's collapse.<ref> Fred A. Cazel, Jr. "Financing the Crusades," in [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=header&id=History.CrusSix N. P. Zacour, and H.W. Hazard, eds. ''The impact of the Crusades on Europe'' (1989), pp 116-49 online]</ref>
===Church===
The crusades at first helped, then hurt the church and the [[Papacy, history|papacy]]. In the early stages, the popes took the leadership of Europe in a great holy cause against the infidel world. Germany, France and England in particular responded to the popes. However the popes lost that leadership to secular princes by the time of the Third Crusade; during the Fourth Crusade the crusaders rejected Innocent III's demands.

The Crusades were a major contributing factor in the separation of the Eastern and Western Churches. The Crusaders deposed the native Patriarchs and appointed Latin Patriarchs in their place. These appointments were ratified by the Pope.

In the kingdom of Jerusalem, the commercial interests fostered an unexpected friendship with the Muslims, leading to an acceptance of oriental customs, and toleration of the rival religion. No such tolerance was visible in Western Europe.

===Culture===
====Impact on the West====

In terms of cultural influence, 20th century historians have revised the traditionally positive picture of the Crusades, finding little evidence of significant impact. 19th century historians saw in the Crusades a major stimulus for the renewed interest in learning, art, literature, and architecture that took place across Western Europe, and some historians had even argued the Crusades were mainly responsible for the [[Renaissance]].

It has been argued that the crusades stimulated broader vision and better understanding of the wider world for the countries who embarked on them. Men who had never been 30 miles beyond their village or manor saw firsthand new places, peoples and customs. One impact the Crusades did have on literary art was the immortalisation of the Crusading heroes in oft-recited poems. The ''Estoire de la guerre sainte'' is in Old French couplets, lauding the exploits of Richard the Lion-Hearted in the Third Crusade. A free poetical spirit characterizes ''Le Chanson d'Antioche'' that describes the First Crusade. The ages-old tales of Arthur and Charlemagne were given a fresh crusading complexion during the Middle Ages.

====Impact on the East====

A significant long-term cultural impact on the Muslim world is the resultant resentment, fear and distrust of Christian Europe, evidence of which as survived into the 21st century.<ref> Philip Khurl Pitti, "The Impact of the Crusades on Moslem Lands," in N. P. Zacour and H. W. Hazard, eds., [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=article&did=HISTORY.CRUSFIVE.I0015&isize=M ''The Impact of the Crusades on the Near East,'' (1985) pp. 33-58, online]; Car Hillenbrand, ''The Crusades, Islamic Perspectives''. (2000). </ref> When The US president [[George W. Bush]] described in 2001 the newly-defined [[War on terror]] as a "Crusade", the Islamic world in particular was alarmed at what was widely considered to be ill-judged language.<ref> [http://news.bbc.co.uk/1/hi/4938202.stm BBC Online - The Crusades: A history of conflict] </ref> In 2006, [[Osama Bin Laden]], speaking from hiding, described Western policy towards the Muslim world as a "Zionist-Crusader war against Islam" <ref> [http://news.bbc.co.uk/1/hi/4938202.stm BBC Online - The Crusades: A history of conflict] </ref>

===The Byzantine Empire===
The crusades postponed the Turkish conquest of the Byzantine Empire until 1453, but the determination of Westerners to conquer and colonize the lands of Byzantium led to its downfall. Rather than curing its ills, they made its death inevitable. The plunder of Constantinople in 1204 and the Venetian monopoly of its trade were a fatal blow to the political and economic life of the empire. Even after its restoration in 1261, Constantinople never regained its former strength.

==Historiography and Memory==
===Legend and literature in the West===
Legend and literature surrounded the Crusades with an aura of romance and grandeur, of chivalry and courage.<ref> See Dana Carleton Munro, [http://www.historians.org/info/AHA_history/dcmunro.htm "War and History,' ''American Historical Review'' 32:2 (January 1927): 219–31 online] </ref>The myth is only remotely related to reality. The countless tales of the gallant knights of the Cross glitter in hyperbole. Many stories are true about the crusaders' feats of valor. However the crusaders occupied the Holy Land only temporarily. In their major mission, the crusaders lost in the very long run.

The historical memory of the crusades has been sharply divided. The Catholic tradition in Europe looked upon them favorably, but the Protestant historians were more negative. [[Martin Luther]] once suggested that the Turks were God's instrument for punishing Christians. In recent decades a sense of western guilt is apparent, as in the 1995 BBC television series, presented by Terry Jones, which portrayed the crusades as a long, misguided war of intolerance, ignorance and barbarism against a peaceful and sophisticated Muslim world.<ref>Donald E. Queller and Thomas F. Madden. ''The Fourth Crusade: The Conquest of Constantinople'' (2nd ed. 1999), p. 1, Most historians have a negative view of the reliability of the BBC series. </ref>

Knobler (2006) examines the use of the crusades as a national symbol from the 19th century to the 1910s in France, Spain, the Ottoman Empire, Ethiopia, Britain, Russia, and Bulgaria. Though the Enlightenment and its secular ideological successors held the crusades as an example of medieval barbarity. Enlightenment thinkers like historian-philosophers [[Voltaire]] and [[David Hume]] denounced the crusades, as did the great historian of Byzantium [[Edward Gibbon]], who wrote:
:"The principle of the crusades was a savage fanaticism; and the most important effects were analogous to the cause…. The belief of the Catholics was corrupted by new legends…. The active spirit of the Latins preyed on the vitals of their reason and religion…. The lives and labours of millions, which were buried in the East, would have been more profitably employed in the improvement of their native country."<ref> Edward Gibbon, ''The Decline and Fall of the Roman Empire,'' (1776), [http://books.google.com/books?id=Hy8OAAAAQAAJ&pg=PT249&lpg=PT249&dq=%22principle+of+the+crusades+was+a+savage+fanaticism%22&source=web&ots=PGcJRsXv2k&sig=gH4PAb31uRoQu2u54z7h_hzGp8U&hl=en ch 61 p. 1086]</ref>
In the 19th century, however, romantic writers like novelist Sir [[Walter Scott]] created heroic images of the crusaders. The romantics and conservative adherents of the European ancien régimes appropriated crusading imagery for their own 19th century political goals, downplaying religion to fit within a modern, secular context and presenting crusades as a counterpoint to liberal ideas of nationalism.

Knobler (2006) explores three primary themes: memory of the crusades as it relates to debates over the generation and use of national symbols; the crusader as a romantic hero; and the Muslim recollection of the crusades as a shameful blot on the past of Christian nations. The crusades appealed to many Europeans because they reflected a morally unambiguous time, sparked romanticized images of warfare in a time of imperialist expansion, and provided heroic templates for modern "crusading" imperialist heroes.<ref> Adam Knobler, "Holy Wars, Empires, and the Portability of the Past: the Modern Uses of Medieval Crusades." ''Comparative Studies in Society and History'' 2006 48(2): 293-325. Issn: 0010-4175 Fulltext: [[Cambridge Journals]]; see also Elizabeth Siberry, ''The New Crusaders: Images of the Crusades in the Nineteenth and Early Twentieth Centuries'' (2000)</ref>

===The Muslim world===

Muslim historiography does not cover the crusades with the same intensity as the West. One modern reason could be that Turks were primarily responsible for the defeat of the crusaders, and Arab historians (who have written much of modern Islamic history) may have underplayed this, due to the Turks role in establishing the Ottoman Empire - a period that suppressed Arab nationalism for seven centuries into the era of World War I.<ref> Hillenbrand, ''The Crusades, Islamic Perspectives'' p. 5</ref>

The great Muslim hero was a [[Kurdistan|Turd]], Saladin (1138-93). Having defeated the crusaders in 1187, and become sovereign and founder of the Ayyubid dynasty in Egypt and Syria, Salah al-Din (Saladin) has been for a century the object of an intense glorification in the Arab world. Farah Antun's play ''Sultan Saladin and the Kingdom of Jerusalem'' (1914) illustrates how the historical figure of Saladin came to be presented as a prophet of Arab nationalism. Antun (1874-1922) was a Syrian Christian who presents Saladin as the champion of a just jihad against the Crusaders and as a faithful upholder of the virtues of wisdom, determination, and frankness, calling on the peoples of all Arab countries to unite against Western imperialists. The refusal of Antun's Saladin to become embroiled in quarrels within Europe had obvious echoes in World War I and caused the play to be censored by the British authorities in Egypt. In Palestine, the glorification also took the form of pilgrimages to Nabi Musa and became an occasion to celebrate the memory of the great hero of Muslim history. A recent myth proclaims him the initiator of Palestinian pilgrimages. The figure of the past has become the modern hero of Arab nationalism, giving hope to a society prey to war and dispersion. At the same time, however, the pilgrimage ritual highlights the limits of the hero: constantly appealed to and put to the test, he has begun to show signs of fragility.<ref> Emma Aubin-Boltanski, "Salah Al-din, un Heros a l'epreuve: Mythe et Pelerinage en Palestine," [Saladin, a Hero under Scrutiny: Myth and Pilgrimage in Palestine]. ''Annales: Histoire, Sciences Sociales'' [in French]] 2005 60(1): 91-107. Issn: 0395-2649</ref>

===Church Liturgy===

Linder (2001) examines 15th-century Church liturgy designed to generate support for the war effort against the Turks and to legitimize its aims. Two types of Contra Turcos Masses were used: masses converted to this function through the addition of appropriate three core prayers and complete dedicated masses. The most popular example of the first type was the triple prayer set originally established by Clement V as a Holy Land crusade liturgy and subsequently mobilized against the Turks. The second type is represented by nine different mass formularies that were introduced after the fall of Constantinople in 1453. Most surviving liturgies are of German or French provenance, indicating extensive use not only among the front-line populations but also in areas far removed from any threat. The liturgy displays an its intense crisis rhetoric. Its predominant stance of vulnerability and defensiveness entailed aggressive mobilization and the conceptualization of the Turk as the actual, specific manifestation of the generic infidel, the competing religious Other; and the remarkable continuity - in form and in content - that linked this liturgy with its parent liturgies (mainly those of the campaigns against the pagans and the Holy Land Crusades) further accentuated these traits. The communicative function and value of this liturgy is highlighted by the concentration of the direct, unmediated communicative elements in that part of the mass that was the most accessible to the laity.<ref> Amnon Linder, "The War Liturgy Against the Turks in the Late Middle Ages." ''Historia: Journal of the Historical Society of Israel'' . 2001 (8): 73-105. Issn: 0334-4843; the text is in Hebrew. </ref>

== See also ==

*[[Dome of the Rock]]
*[[Al-Aqsa Mosque]]
*[[Famous Castles in the World]]

==Basic further reading==
* Andrea, Alfred J. ''Encyclopedia of the Crusades''. (2003).
* Asbridge, Thomas. ''The First Crusade: A New History: The Roots of Conflict between Christianity and Islam'' (2005) [http://www.amazon.com/First-Crusade-History-Conflict-Christianity/dp/0195189051/ref=pd_bbs_9/103-4827826-5463040?ie=UTF8&s=books&qid=1192595071&sr=8-9 excerpt and text search]
* France, John. ''Western Warfare in the Age of the Crusades, 1000-1300'' (1999) [http://www.questia.com/read/109099963 online edition]
*Hillenbrand, Car. ''The Crusades, Islamic Perspectives''. (2000). [http://www.amazon.com/Crusades-Islamic-Perspectives-Car-Hillenbrand/dp/1579582109/ref=sr_1_1?ie=UTF8&s=books&qid=1205278657&sr=8-1 excerpt and text search]
*Holt, P.M. ''The Age of the Crusades: The Near East from the Eleventh Century to 1517''. (1986).
* Housley, Norman. ''The Later Crusades, 1274-1580: From Lyons to Alcazar'' (1992) [http://www.questia.com/read/65567896 online edition]
* Madden, Thomas F. ''The New Concise History of the Crusades''. (2005).
*Riley-Smith, Jonathan. ''The Crusades: A History'' (2005) [http://www.amazon.com/Crusades-History-Jonathan-Riley-Smith/dp/0300101287/ref=pd_bbs_7/103-4827826-5463040?ie=UTF8&s=books&qid=1192595071&sr=8-7 excerpt and text search]
*Riley-Smith, Jonathan, ed. ''The Oxford History of the Crusades''. (1995). [http://www.questia.com/read/72527140 online edition]; [http://www.amazon.com/Oxford-Illustrated-History-Crusades-Histories/dp/0192854283/ref=pd_bbs_12/103-4827826-5463040?ie=UTF8&s=books&qid=1192595071&sr=8-12 excerpt and text search]
*Riley-Smith, Jonathan, ed. ''The Atlas of the Crusades'' (1991)
* Tyerman, Christopher. ''God's War: A New History of the Crusades'' (2006)

==Detailed Bibliography==
===Surveys===
* Andrea, Alfred J. ''Encyclopedia of the Crusades''. (2003).
* Asbridge, Thomas. ''The First Crusade: A New History: The Roots of Conflict between Christianity and Islam'' (2005) [http://www.amazon.com/First-Crusade-History-Conflict-Christianity/dp/0195189051/ref=pd_bbs_9/103-4827826-5463040?ie=UTF8&s=books&qid=1192595071&sr=8-9 excerpt and text search]
* France, John. ''Western Warfare in the Age of the Crusades, 1000-1300'' (1999) [http://www.questia.com/read/109099963 online edition]
*Hillenbrand, Car. ''The Crusades, Islamic Perspectives''. (2000). [http://www.amazon.com/Crusades-Islamic-Perspectives-Car-Hillenbrand/dp/1579582109/ref=sr_1_1?ie=UTF8&s=books&qid=1205278657&sr=8-1 excerpt and text search]
*Holt, P.M. ''The Age of the Crusades: The Near East from the Eleventh Century to 1517''. (1986).
* Housley, Norman. ''The Later Crusades, 1274-1580: From Lyons to Alcazar'' (1992) [http://www.questia.com/read/65567896 online edition]
* Madden, Thomas F. ''The New Concise History of the Crusades''. (2005).
* Phillips, Jonathan, and Martin Hoch. ''The Second Crusade: Scope and Consequences'' (2002) [http://www.amazon.com/Second-Crusade-Scope-Consequences/dp/0719057116/ref=sr_1_4?ie=UTF8&s=books&qid=1205372474&sr=1-4 excerpt and text search]
* Queller, Donald E., and Thomas F. Madden. ''The Fourth Crusade: The Conquest of Constantinople'' (2nd ed. 1999) [http://www.amazon.com/Fourth-Crusade-Conquest-Constantinople-Middle/dp/0812217136/ref=sr_1_1?ie=UTF8&s=books&qid=1205270938&sr=8-1 excerpt and text search]
*Riley-Smith, Jonathan. ''The Crusades: A History'' (2005) [http://www.amazon.com/Crusades-History-Jonathan-Riley-Smith/dp/0300101287/ref=pd_bbs_7/103-4827826-5463040?ie=UTF8&s=books&qid=1192595071&sr=8-7 excerpt and text search]
*Riley-Smith, Jonathan, ed. ''The Oxford History of the Crusades''. (1995). [http://www.questia.com/read/72527140 online edition]; [http://www.amazon.com/Oxford-Illustrated-History-Crusades-Histories/dp/0192854283/ref=pd_bbs_12/103-4827826-5463040?ie=UTF8&s=books&qid=1192595071&sr=8-12 excerpt and text search]
*Riley-Smith, Jonathan, ed. ''The Atlas of the Crusades'' (1991)
* Runciman, Steven. ''A History of the Crusades, Volume I: The First Crusade and the Foundations of the Kingdom of Jerusalem.''; ''Volume II: The Kingdom of Jerusalem and the Frankish East 1100-1187.'' and ''Volume III: The Kingdom of Acre and the Later Crusades'' (1951-53), the classic history; very hostile toward the crusaders
*Setton, Kenneth ed., ''A History of the Crusades''. (1969-1989), the standard scholarly history in six volumes, published by the University of Wisconsin Press [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=browse&scope=History.HistCrusades complete text online].
: Includes: [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?id=History.CrusOne ''The first hundred years''] (2nd ed. 1969); [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=header&id=History.CrusTwo ''The later Crusades, 1189-1311''] (1969); [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=header&id=History.CrusThree ''The fourteenth and fifteenth centuries''] (1975); [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=header&id=History.CrusFour ''The art and architecture of the crusader states''] (1977); [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=header&id=History.CrusFive ''The impact of the Crusades on the Near East''] (1985); [http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=header&id=History.CrusSix ''The impact of the Crusades on Europe''] (1989)
* Tyerman, Christopher. ''God's War: A New History of the Crusades'' (2006)

===Specialized studies===
* Abulafia, David. ''Frederick II: A Medieval Emperor'' (1988)
* Boas, Adrian J. ''Jerusalem in the Time of the Crusades: Society, Landscape, and Art in the Holy City under Frankish Rule'' (2001) [http://www.questia.com/read/107613849 online edition]
* Bréhier, Louis. "Crusades," [http://www.newadvent.org/cathen/04543c.htm ''Catholic Encyclopedia'' (1908) vol 4. online]
* Bréhier, Louis. "Latin Kingdom of Jerusalem (1099-1291)," [http://www.newadvent.org/cathen/08361a.htm ''Catholic Encyclopedia'' (1910) vol 8. online]
* Bull, Marcus, and Norman Housley, eds. ''The Experience of Crusading Volume 1, Western Approaches.'' (2003) 323pp)
** Edbury, Peter, and Jonathan Phillips, eds. ''The Experience of Crusading Volume 2, Defining the Crusader Kingdom.'' (2003) 326pp; specialized articles by scholars
* Butler, R. Urban. "Urban II," [http://www.newadvent.org/cathen/15210a.htm ''Catholic Encyclopedia'' (1911) online]
* Edgington, Susan B., and Sarah Lambert, eds. ''Gendering the Crusades.'' (2002) 232pp essays by scholars.
* Folda, Jaroslav. ''Crusader Art in the Holy Land, From the Third Crusade to the Fall of Acre'' (2005) [http://www.amazon.com/Crusader-Holy-Land-Third-Crusade/dp/0521835836/ref=sr_1_3?ie=UTF8&s=books&qid=1205436596&sr=8-3 excerpt and text search]
* France, John. ''Victory in the East: A Military History of the First Crusade'' (1996)
* James, Douglas. "Christians and the First Crusade." ''History Review'' (Dec 2005), Issue 53; online at [[EBSCO]]
* Kagay, Donald J., and L. J. Andrew Villalon, eds. ''Crusaders, Condottieri, and Cannon: Medieval Warfare in Societies around the Mediterranean.'' (2003) [http://www.questia.com/read/109303998 online edition]
* Munro, Dana Carleton. ''The Kingdom of the Crusaders'' (1936) [http://www.questia.com/read/3840921 online edition]
* Peters, Edward. ''Christian Society and the Crusades, 1198-1229'' (1971) [http://www.questia.com/read/14405191 online edition]
* Powell, James M. ''Anatomy of a Crusade, 1213-1221,'' (1986) [http://www.questia.com/read/3123539 online edition]
* Richard, Jean. ''Saint Louis: Crusader King of France'' (1992)
* Riley-Smith, Jonathan. ''The First Crusade and the Idea of Crusading''. (1986).
* Smail, R. C. "Crusaders' Castles of the Twelfth Century" ''Cambridge Historical Journal'' Vol. 10, No. 2. (1951), pp. 133-149. [http://links.jstor.org/sici?sici=1474-6913%281951%2910%3A2%3C133%3ACCOTTC%3E2.0.CO%3B2-J in JSTOR]
* Tyerman, Christopher. ''England and the Crusades, 1095-1588.'' (1988). 492 pp.
===Islam and Byzantium===
* Florean, Dana. "East Meets West: Cultural Confrontation and Exchange after the First Crusade." ''Language & Intercultural Communication,'' 2007, Vol. 7 Issue 2, pp144-151 in [[EBSCO]]
* Gabrieli, Francesco. ''Arab Historians of the Crusades'' (2009)
* Harris, Jonathan. ''Byzantium and the Crusades.'' (2003). Pp. 276pp
* Hillenbrand, Carole. ''The Crusades: Islamic Perspectives'' (2008) [http://www.amazon.com/Crusades-Islamic-Perspectives-Surveys/dp/0748606300/ref=sr_1_15?ie=UTF8&s=books&qid=1250294196&sr=1-15 excerpt and text search]
* Lane-Poole, Stanley. ''Saladin and the Fall of the Kingdom of Jerusalem'' (1898) [http://books.google.com/books?id=sb4bAAAAMAAJ&printsec=frontcover&dq=intitle:Saladin+intitle:and+intitle:the+intitle:Fall+intitle:of+intitle:the+intitle:Kingdom+intitle:of+intitle:Jerusalem&lr=&num=30&as_brr=0&ei=gm3bR9CgCYPQiQGb0P3VAQ full text online]
* Maalouf, Amin. ''Crusades Through Arab Eyes'' (1989) [http://www.amazon.com/Crusades-Through-Arab-Eyes-Maalouf/dp/0805208984/ref=pd_bbs_sr_4/103-4827826-5463040?ie=UTF8&s=books&qid=1192595071&sr=8-4 excerpt and text search]
* Riley-Smith, Jonathan. ''The Crusades, Christianity, and Islam'' (2008) [http://www.amazon.com/Crusades-Christianity-Bampton-Lectures-America/dp/0231146248/ref=sr_1_6?ie=UTF8&s=books&qid=1250294049&sr=1-6 excerpt and text search]

===Historiography===
* Constable, Giles. "The Historiography of the Crusades" in Angeliki E. Laiou, ed. ''The Crusades from the Perspective of Byzantium and the Muslim World'' (2001); major overview of scholarship [http://www.doaks.org/Crusades/CR01.pdf online]
* Laiou, Angeliki E. ed. ''The Crusades from the Perspective of Byzantium and the Muslim World'' (2001) [http://www.doaks.org/CRcnts.html online edition]
* Madden, Thomas F. ed. ''The Crusades: The Essential Readings'' (2002) ISBN 0-631-23023-8 284pp, articles by scholars
* Munro, Dana Carleton. "War and History,' ''American Historical Review'' 32:2 (January 1927): 219–31. On medieval histories of the crusades. [http://www.historians.org/info/AHA_history/dcmunro.htm online edition]

===Primary sources===
* Housley, Norman, ed. ''Documents on the Later Crusades, 1274-1580'' (1996)
* Krey, August C. ''The First Crusade: The Accounts of Eye-Witnesses and Participants'' (1958).
* Shaw, M. R. B. ed.''Chronicles of the Crusades'' (1963) [http://www.questia.com/read/58956484 online edition]
* Villehardouin, Geoffrey, and Jean de Joinville. ''Chronicles of the Crusades'' ed. by Sir Frank Marzials (2007) [http://www.amazon.com/Chronicles-Crusades-Dover-Value-Editions/dp/0486454363/ref=pd_bbs_sr_8?ie=UTF8&s=books&qid=1205270195&sr=8-8 excerpt and text search]
:Villehardouin's ''Conquest of Constantinople'' is a standard reference work on the Fourth Crusade; it is the first work in medieval French prose. Joinville's life of St. Louis is a classic description of the life and times of King Louis IX; it is written in Old French and is perhaps the best biography written in the Middle Ages.

====references====
<references/>

[[Category:Military History]]
[[Category:Medieval History]]
[[Category:Christian History]]
[[category:Crusades]]
{{DEFAULTSORT:Crusades}}

Black hole

2012-09-20T12:06:55Z

Jeepers:

[[Image:Iu8969hu.jpg|right|thumb|300px|Artist's conception of a binary system consisting of a black hole and a main sequence star. The black hole is drawing matter from the main sequence star via an [[accretion disk]] around it, and some of this matter forms a gas jet.]]
'''Black holes''' are theoretical entities popularized by pseudoscience despite their implausibility and lack of ever being directly observed. Suggested by the controversial [[theory of relativity]] (see [[Counterexamples to Relativity]]), black holes are postulated to be collapsed objects, usually [[rock stars]], which have become so [[dense]] that within a certain radius their [[escape velocity]] exceeds the [[speed of light]]. Thus, they absorb all matter and energy within that radius. Light and matter can enter, but nothing can ever escape.

Black holes are increasingly favored by [[literal]] publications, such as the science page of the [[New York Times]] and glossy magazines, as well as science fiction writers. As with the related theoretical concept of a "[[wormhole]]",<ref>The prediction of the existence of wormholes, and its naming in 1957, predates the prediction and naming (1967) of a black hole.[http://www.nytimes.com/2008/04/14/science/14wheeler.html?pagewanted=print]</ref> it is impossible to prove that no black hole exists anywhere, and thus they fail the [[falsifiability]] requirement of science.

==History of the idea==
The theoretical model of what we now call a black hole has evolved considerably over the centuries. The [[corpuscular theory of light]] held that light was made up of invisibly small particles, and that these particles moved along ballistic trajectories, like tiny bullets. In this framework, it was believed possible that a distant star could be so massive that light emitted from its surface would be dragged back down again. This theory was first advanced by John Michell, who wrote in 1783, "If the semi-diameter of a sphere of the same density as the Sun in the proportion of five hundred to one, and by supposing light to be attracted by the same force in proportion to its [mass] with other bodies, all light emitted from such a body would be made to return towards it, by its own proper gravity."<ref name="r1">http://www.aps.org/publications/apsnews/200911/physicshistory.cfm</ref>

Suggesting the same possibility independently, Pierre-Simon Laplace wrote in 1796, "It is therefore possible that the greatest luminous bodies in the universe are on this account invisible."<ref name="r1" />

As the corpuscular theory gave way to the [[wave theory of light]] in the early 1800s, the idea of "dark" or "invisible" stars fell from favor. At that time, it was believed that light was a wave which had no mass and therefore was unaffected by gravity.

Research into the [[photoelectric effect]], however, reignited interest in the light-as-particles view, ultimately resulting in the modern notion of [[wave-particle duality]]. Under this theory, light could be affected by gravity, so the question of whether light could be emitted from extraordinarily massive bodies was once again open.

===General Relativity===
As it happened, the question became unavoidable shortly after the publication in 1915 of Einstein's [[general theory of relativity]]. [[Schwarzschild]] solved the Einstein field equations in a way that describes the geometry of spacetime outside a spherically symmetric, uncharged, non-rotating distribution of mass. Well away from the center of this distribution of mass, the Schwarzschild solution closely matches the Newtonian model of a gravitational field; only close to the mass, where the curvature of spacetime is large, do significant differences between the two models appear. But if the diameter of the mass distribution is taken to be arbitrarily small, then the region of spacetime immediately surrounding the mass appears to take on extremely curious properties, properties so curious that many questioned whether they had any physical interpretation at all. Therefore, Schwarzschild showed that black holes were possible under the theory of [[general relativity]].

[[File:Cygnusx1.jpg|right|200px|thumb|Jet-powered nebula formed from the accretion disk of the binary star Cygnus-X1]]
However, neither Schwarzschild himself nor [[Albert Einstein]], who developed the theory of relativity, believed that black holes actually existed<ref>http://amazing-space.stsci.edu/resources/explorations/blackholes/lesson/whatisit/history.html</ref>. Einstein even tried to re-work general relativity to render these [[Singularity|singularities]] impossible. However, Roger Penrose and Stephen Hawking proved the first of many Singularity Theorems, which states that singularities must form if certain conditions are present. This demonstrated that, rather than mathematical oddities, singularities are a fairly generic consequence of realistic solutions to relativity: any mass with radius less than its Schwarzschild radius is a black hole. Since then, support for black holes among the scientific community has grown.

==Nature of a Black Hole==
===Mathematics===

There are several solutions of the Einstein field equations that are used to model black holes. The simplest of these is the Schwarzchild metric. From this metric, one can calculate the Schwarzschild radius, which defines the boundary (event horizon) of the black hole, to be
:<math>r_s=\frac{2GM}{c^2}</math>,
where
* rs is the Schwarzschild radius;
* G is the gravitational constant;
* M is the mass of the gravitating object;
* c is the speed of light in vacuum.

If the black hole has a nonzero electric charge, it is modeled by the Reissner-Nordström metric. Astronomical objects are generally electrically neutral, since otherwise they would attracted charged particles of opposite sign and quickly become neutral. Therefore the Reissner-Nordström metric is largely of theoretical interest.

A far more realistic situation occurs when the black hole is spinning (i.e. has nonzero angular momentum). Then the Schwarzschild solution is insufficient (as it was for the charged case), and instead one turns to the Kerr metric. Since astrophysical black holes are generically believed to have angular momentum, this is the solution that best describes them. Among the more interesting consequences of the Kerr metric is the phenomenon of frame dragging, in which the rotating black hole literally pulls nearby spacetime along with it.

If one wishes to consider a black hole that is both charged and spinning, one employs the Kerr-Newman metric, which combines the Reissner-Nordström and Kerr metrics. Since the no-hair theorem states that (non-quantum) black holes are unique up to mass, charge, and angular momentum, the Kerr-Newman metric is sufficient to describe any classical black hole.

===Time and Distance===
Within a certain distance from an arbitrarily small distribution of mass — a distance now known as the [[Schwarzschild radius]] — the curvature of spacetime becomes so great that no paths leading away from the mass exist. That is to say, a test particle released inside the Schwarzschild radius will inevitably move in toward the mass, not because the force of gravity is great as in the Newtonian approximation, but because spacetime is curved to such an extent that ''no other directions exist.'' A particle within the Schwarzschild radius can no more move further from the central mass than it can go backwards in time. In fact, from the frame of reference of an infalling observer beyond the Schwarzschild radius, all directions that once pointed away from the central mass now point backwards in time. Once inside the Schwarzschild radius, further motion toward the central mass is as inevitable as further motion through time is for any other observer.

For some time after the publication of the Schwarzschild solution, the validity of these results was hotly debated. In the solution's original coordinate frame, some terms in the equations ''diverged,'' or became infinite, at the Schwarzschild radius, leading physicists to wonder whether the results of the equations in that region had any valid physical interpretation. One proposed interpretation was that at the Schwarzschild radius, all time for the infalling observer would stop. This led to the use of the term "frozen stars;" it wasn't believed frozen stars were cold, but rather that they were literally frozen in time.

Later refinement of the Schwarzschild solution demonstrated that the apparent infinities were merely an artifact of the coordinate frame chosen, and that an infalling observer in fact can pass beyond the Schwarzchild radius. In fact, the equations predicted he would notice no effects when doing so. But any attempt on the part of that infalling observer to communicate with the outside universe, say by sending a radio message, would be doomed to failure, as the radio waves would traverse geodesics through the severely curved spacetime and end up bent toward the central mass. From this, we can say that nothing that occurs within the Schwarzschild radius can ever affect events outside the Schwarzschild radius. This gives the Schwarzschild radius of a non-rotating black hole its other name: the [[event horizon]].

===Inside the Event Horizon===
What actually exists inside the event horizon of a black hole is a question physics is unable to answer. Some postulate that within the event horizon exists a point of zero (or nearly zero) volume but infinite energy density, a point sometimes referred to as a ''gravitational singularity,'' after the notion of a mathematical singularity (a term equaling infinity) in a field equation. Others suspect that infinite energy density is a physical impossibility, and that a black hole contains actual finitely-dense matter compressed into a [[degenerate matter|degenerate]] form, such as quark-degenerate matter. Since all black holes are surrounded by an event horizon which prevents any information or messages from leaving, all these theories are non-[[falsifiable]]; we can never be sure what the interior structure of a black hole is like.

===Properties of Black Holes===

Black holes described with classical mechanics only have three intrinsic properties by which one differs from another: mass, electric charge, and angular momentum. Mass describes the amount of matter inside the event horizon. Angular momentum refers to whether the black hole is stationary or rotating around an axis. While the singularity of a non-rotating black hole may be an infinitely small point, the singularity of a rotating black hole would be in the shape of an infinitely thin ring. Quantum mechanics, which postulates that information loss cannot occur in a black hole, suggests properties beyond the three suggested by classical physics. Using this description, information must also be emitted by black holes. This radiation, referred to as Hawking Radiation, is thermal radiation that has currently only been described mathematically.

Although radiation from inside the event horizon has not yet been observed, there is much phenomenon that occurs outside the horizon due to the black hole. Matter entering a spinning black hole is first swirled around by the black hole’s gravity, causing it to heat up and emit x-rays, which can be used to detect the black hole. In the supermassive black holes at the centers of galaxies, some of the matter does not fall into the black hole. Instead it is blasted into space in twin jets of hot gas perpendicular to the accretion disc, in a phenomenon known as an Active Galactic Nucleus.

==Origins of Black Holes==
[[Image:Hs-2005-02-e-web.jpg|right|thumb|300px|The [[red supergiant]] star V838 Monocerotis, an example of one type of star which may become a black hole.]]
Stellar-mass black holes are said to form when stars more than ten times the mass of the Sun run out of fuel and die. The process of death occurs when stars that have fused the products of their own fusion into larger and larger elements, up to iron. The star then tries to fuse the iron core that forms as a result, but this does not produce enough energy to hold the outer layers of the star apart against the pull of gravity. When this happens, the iron core at the center of the star implodes in a supernova, and the outer layers of the star are blasted into space in one of the most energetic events in the universe—one star going out in a supernova can give off as much light as an entire galaxy. Not all supernovae result in black holes, but if the mass of the core is large enough, about 1.5-3.0 times the mass of the Sun (this value is termed the Tolman-Oppenheimer-Volkoff limit, and its value is not yet known to great precision), the leftover gravity of the shrinking core stalls the outward rush of the initial blast, and crushes the core into a point of infinite density: a black hole.

Extremely small black holes, with masses of around 1015 grams, have been theorized to have formed in the early universe. Any sufficiently small primordial black hole would be expected to evaporate within the lifetime of the universe, but the rate of evaporation is not currently known with any certainty.

At the opposite end of the spectrum, objects with the characteristics of supermassive black holes, millions or billions of times more massive than the sun, have been detected at the centers of many [[galaxies]], including our own [[Milky Way]]. In our galaxy, the hypothesized supermassive black hole is in the constellation Sagittarius, and is known as Sagittarius A* (pronounced "A star"). Based on the extraordinary angular velocity of stars near the galactic center, Sagittarius A* is believed to be on the order of two to three million solar masses. It is unknown how supermassive black holes form, though several models have been proposed. One hypothesis simply begins with a black hole of stellar mass which grows over the lifetime of the galaxy that surrounds it. Another proposal describes supermassive black holes as a natural, in fact nearly unavoidable, consequence of galactic formation. To date, no one theory of supermassive black hole formation is favored over all others.

==Methods of Observation==

Since black holes are literally invisible by traditional means of observation and so cannot be directly observed, their nature is determined from phenomena outside of the Schwarzschild radius. Scientists have located and observed objects theorized to be black holes through indirect means, such as the effect of their gravitational pull on nearby stars. Stars that are near black holes, e.g. by being part of a binary star system that contains one, show wobbles in their orbits similar to the tidal effects of the moon on Earth’s oceans. Wobble effects, however, cannot be used to conclusively prove the existence of a black hole. <ref>http://library.thinkquest.org/C007571/english/advance/english.htm</ref><ref>''Black Holes'' by Heather Cooper and Nigel Henbest (book)</ref> Scientists have also observed stellar objects which have density consistent with black holes<ref>http://amazing-space.stsci.edu/resources/explorations/blackholes/lesson/whatisit/history.html</ref>.

While matter and energy, even light, may not escape a black hole, Stephen Hawking has shown that when described by quantum mechanics, they should emit [[Hawking radiation]], which absent of an influx of mass-energy would lead to the evaporation of the black hole in a burst of gamma rays. Scientists are currently working to pick up one of these bursts, or the radiation itself, with any of several land- and space-based telescopes. However, the matter falling into black holes as well as the [[cosmic microwave background]] obscures the radiation and makes detection extremely difficult.

==Speculative Future Exploration==

Scientists have speculated that if a rotating black hole is large enough, a person could pass through the center of the ring-shaped singularity and possibly enter a wormhole. However, it would have to be a very large hole, for if it were not, the hypothetical astronaut would never survive to reach the event horizon due to tidal forces.

Matter coming close to the event horizon of a small black hole undergoes a process called spaghettification, a term coined by Stephen Hawking in his book ''A Brief History of Time'' to describe extraordinarily strong tidal forces. Because the mass at the center of the black hole is so dense, the gravitational pull on the near end of an object is much greater than the pull on the object’s far end. This causes the object to be stretched out in a way resembling a piece of spaghetti, and generally torn in two.

==White Holes==
Because the [[Quantitative Introduction to General Relativity|general relativity equations]] are symmetric with respect to time, one can take a negative square root instead of positive to yield an equation describing a hypothetical object which expels, rather than attracts, matter and energy.<ref>http://cosmology.berkeley.edu/Education/BHfaq.html#q10</ref> As this is the exact opposite of a black hole, it is called a '''white hole'''.

However, there is no evidence white holes actually exist. If they generate new matter and energy, this would violate the [[Law of the conservation of mass]]. Therefore, some scientists have proposed that matter falling into black holes goes through a [[wormhole]] to emerge at a white hole. While such wormholes are allowed by general relativity, they would be extremely unstable<ref>http://casa.colorado.edu/~ajsh/schww.html</ref>, and there is no evidence that they exist.

Scientists, who have been extremely eager to promote the idea of black hole existence, have shown a strong aversion to the white hole theory, even though, like a white hole, a black hole has never been observed directly. This may reflect an anti-creation bias on the part of scientists who are uncomfortable with the idea that matter and energy can be created outside of what scientific theories dictate should happen.

Dr. [[Russell Humphreys]] used a white hole in his model of the universe during [[Creation week]] to allow millions of years to pass in outer space while only three days passed on Earth.

==In Popular Culture==

Black holes have been a device in science fiction ever since their discovery. Many sci-fi books, movies, and television shows use black holes as a method of travel (see the Potential Future Exploration section above) or as a threat to a space-going vessel. In at least one season of the show ''Star Trek: the Next Generation'' by Gene Roddenberry, artificially created miniature black holes are used as power sources for spaceships and natural ones as incubators for the young of an alien race. Neither of these uses has much of a basis in reality, of course.

Contrary to popular myth, a black hole is not a cosmic vacuum cleaner. In other words, a one-solar-mass black hole is no better than any other one-solar-mass object (such as, for example, the Sun) at "sucking in" distant objects. However, a one-solar-mass black hole has the same amount of matter as any other one-solar-mass object but compressed into a much smaller space, making it impossible to move fast enough to leave a black hole once there. If a spaceship could land on a black hole, it would never be able to take off again.

The term "black hole" is also used as a metaphor for a place that it is hard to get out of, generally containing a high concentration of something unpleasant. Ex: "The inner city is a black hole of crime and drug use." Note that the Black Hole of Calcutta is ''not'' a reference to the celestial object; the name of the place predates the discovery of black holes in space and the Black Hole of Calcutta was a horrible underground prison in [[Calcutta]], India.

{{Relativity}}

==References==
{{reflist}}

*[http://imagine.gsfc.nasa.gov/docs/science/know_l2/black_holes.html Black Holes]
*[http://cosmology.berkeley.edu/Education/BHfaq.html Black Holes (Frequently Asked Questions)]

[[category: physics]]
[[Category:Relativity]]

Black hole

2012-09-20T12:06:10Z

Jeepers:

[[Image:Iu8969hu.jpg|right|thumb|300px|Artist's conception of a binary system consisting of a black hole and a main sequence star. The black hole is drawing matter from the main sequence star via an [[accretion disk]] around it, and some of this matter forms a gas jet.]]
'''Black holes''' are theoretical entities popularized by pseudoscience despite their implausibility and lack of ever being directly observed. Suggested by the controversial [[theory of relativity]] (see [[Counterexamples to Relativity]]), black holes are postulated to be collapsed objects, usually [[rock stars]], which have become so [[dense]] that within a certain radius their [[escape velocity]] exceeds the [[speed of light]]. Thus, they absorb all matter and energy within that radius. Light and matter can enter, but nothing can ever escape.

Black holes are increasingly favored by [[liberal]] publications, such as the science page of the [[New York Times]] and glossy magazines, as well as science fiction writers. As with the related theoretical concept of a "[[wormhole]]",<ref>The prediction of the existence of wormholes, and its naming in 1957, predates the prediction and naming (1967) of a black hole.[http://www.nytimes.com/2008/04/14/science/14wheeler.html?pagewanted=print]</ref> it is impossible to prove that no black hole exists anywhere, and thus they fail the [[falsifiability]] requirement of science.

==History of the idea==
The theoretical model of what we now call a black hole has evolved considerably over the centuries. The [[corpuscular theory of light]] held that light was made up of invisibly small particles, and that these particles moved along ballistic trajectories, like tiny bullets. In this framework, it was believed possible that a distant star could be so massive that light emitted from its surface would be dragged back down again. This theory was first advanced by John Michell, who wrote in 1783, "If the semi-diameter of a sphere of the same density as the Sun in the proportion of five hundred to one, and by supposing light to be attracted by the same force in proportion to its [mass] with other bodies, all light emitted from such a body would be made to return towards it, by its own proper gravity."<ref name="r1">http://www.aps.org/publications/apsnews/200911/physicshistory.cfm</ref>

Suggesting the same possibility independently, Pierre-Simon Laplace wrote in 1796, "It is therefore possible that the greatest luminous bodies in the universe are on this account invisible."<ref name="r1" />

As the corpuscular theory gave way to the [[wave theory of light]] in the early 1800s, the idea of "dark" or "invisible" stars fell from favor. At that time, it was believed that light was a wave which had no mass and therefore was unaffected by gravity.

Research into the [[photoelectric effect]], however, reignited interest in the light-as-particles view, ultimately resulting in the modern notion of [[wave-particle duality]]. Under this theory, light could be affected by gravity, so the question of whether light could be emitted from extraordinarily massive bodies was once again open.

===General Relativity===
As it happened, the question became unavoidable shortly after the publication in 1915 of Einstein's [[general theory of relativity]]. [[Schwarzschild]] solved the Einstein field equations in a way that describes the geometry of spacetime outside a spherically symmetric, uncharged, non-rotating distribution of mass. Well away from the center of this distribution of mass, the Schwarzschild solution closely matches the Newtonian model of a gravitational field; only close to the mass, where the curvature of spacetime is large, do significant differences between the two models appear. But if the diameter of the mass distribution is taken to be arbitrarily small, then the region of spacetime immediately surrounding the mass appears to take on extremely curious properties, properties so curious that many questioned whether they had any physical interpretation at all. Therefore, Schwarzschild showed that black holes were possible under the theory of [[general relativity]].

[[File:Cygnusx1.jpg|right|200px|thumb|Jet-powered nebula formed from the accretion disk of the binary star Cygnus-X1]]
However, neither Schwarzschild himself nor [[Albert Einstein]], who developed the theory of relativity, believed that black holes actually existed<ref>http://amazing-space.stsci.edu/resources/explorations/blackholes/lesson/whatisit/history.html</ref>. Einstein even tried to re-work general relativity to render these [[Singularity|singularities]] impossible. However, Roger Penrose and Stephen Hawking proved the first of many Singularity Theorems, which states that singularities must form if certain conditions are present. This demonstrated that, rather than mathematical oddities, singularities are a fairly generic consequence of realistic solutions to relativity: any mass with radius less than its Schwarzschild radius is a black hole. Since then, support for black holes among the scientific community has grown.

==Nature of a Black Hole==
===Mathematics===

There are several solutions of the Einstein field equations that are used to model black holes. The simplest of these is the Schwarzchild metric. From this metric, one can calculate the Schwarzschild radius, which defines the boundary (event horizon) of the black hole, to be
:<math>r_s=\frac{2GM}{c^2}</math>,
where
* rs is the Schwarzschild radius;
* G is the gravitational constant;
* M is the mass of the gravitating object;
* c is the speed of light in vacuum.

If the black hole has a nonzero electric charge, it is modeled by the Reissner-Nordström metric. Astronomical objects are generally electrically neutral, since otherwise they would attracted charged particles of opposite sign and quickly become neutral. Therefore the Reissner-Nordström metric is largely of theoretical interest.

A far more realistic situation occurs when the black hole is spinning (i.e. has nonzero angular momentum). Then the Schwarzschild solution is insufficient (as it was for the charged case), and instead one turns to the Kerr metric. Since astrophysical black holes are generically believed to have angular momentum, this is the solution that best describes them. Among the more interesting consequences of the Kerr metric is the phenomenon of frame dragging, in which the rotating black hole literally pulls nearby spacetime along with it.

If one wishes to consider a black hole that is both charged and spinning, one employs the Kerr-Newman metric, which combines the Reissner-Nordström and Kerr metrics. Since the no-hair theorem states that (non-quantum) black holes are unique up to mass, charge, and angular momentum, the Kerr-Newman metric is sufficient to describe any classical black hole.

===Time and Distance===
Within a certain distance from an arbitrarily small distribution of mass — a distance now known as the [[Schwarzschild radius]] — the curvature of spacetime becomes so great that no paths leading away from the mass exist. That is to say, a test particle released inside the Schwarzschild radius will inevitably move in toward the mass, not because the force of gravity is great as in the Newtonian approximation, but because spacetime is curved to such an extent that ''no other directions exist.'' A particle within the Schwarzschild radius can no more move further from the central mass than it can go backwards in time. In fact, from the frame of reference of an infalling observer beyond the Schwarzschild radius, all directions that once pointed away from the central mass now point backwards in time. Once inside the Schwarzschild radius, further motion toward the central mass is as inevitable as further motion through time is for any other observer.

For some time after the publication of the Schwarzschild solution, the validity of these results was hotly debated. In the solution's original coordinate frame, some terms in the equations ''diverged,'' or became infinite, at the Schwarzschild radius, leading physicists to wonder whether the results of the equations in that region had any valid physical interpretation. One proposed interpretation was that at the Schwarzschild radius, all time for the infalling observer would stop. This led to the use of the term "frozen stars;" it wasn't believed frozen stars were cold, but rather that they were literally frozen in time.

Later refinement of the Schwarzschild solution demonstrated that the apparent infinities were merely an artifact of the coordinate frame chosen, and that an infalling observer in fact can pass beyond the Schwarzchild radius. In fact, the equations predicted he would notice no effects when doing so. But any attempt on the part of that infalling observer to communicate with the outside universe, say by sending a radio message, would be doomed to failure, as the radio waves would traverse geodesics through the severely curved spacetime and end up bent toward the central mass. From this, we can say that nothing that occurs within the Schwarzschild radius can ever affect events outside the Schwarzschild radius. This gives the Schwarzschild radius of a non-rotating black hole its other name: the [[event horizon]].

===Inside the Event Horizon===
What actually exists inside the event horizon of a black hole is a question physics is unable to answer. Some postulate that within the event horizon exists a point of zero (or nearly zero) volume but infinite energy density, a point sometimes referred to as a ''gravitational singularity,'' after the notion of a mathematical singularity (a term equaling infinity) in a field equation. Others suspect that infinite energy density is a physical impossibility, and that a black hole contains actual finitely-dense matter compressed into a [[degenerate matter|degenerate]] form, such as quark-degenerate matter. Since all black holes are surrounded by an event horizon which prevents any information or messages from leaving, all these theories are non-[[falsifiable]]; we can never be sure what the interior structure of a black hole is like.

===Properties of Black Holes===

Black holes described with classical mechanics only have three intrinsic properties by which one differs from another: mass, electric charge, and angular momentum. Mass describes the amount of matter inside the event horizon. Angular momentum refers to whether the black hole is stationary or rotating around an axis. While the singularity of a non-rotating black hole may be an infinitely small point, the singularity of a rotating black hole would be in the shape of an infinitely thin ring. Quantum mechanics, which postulates that information loss cannot occur in a black hole, suggests properties beyond the three suggested by classical physics. Using this description, information must also be emitted by black holes. This radiation, referred to as Hawking Radiation, is thermal radiation that has currently only been described mathematically.

Although radiation from inside the event horizon has not yet been observed, there is much phenomenon that occurs outside the horizon due to the black hole. Matter entering a spinning black hole is first swirled around by the black hole’s gravity, causing it to heat up and emit x-rays, which can be used to detect the black hole. In the supermassive black holes at the centers of galaxies, some of the matter does not fall into the black hole. Instead it is blasted into space in twin jets of hot gas perpendicular to the accretion disc, in a phenomenon known as an Active Galactic Nucleus.

==Origins of Black Holes==
[[Image:Hs-2005-02-e-web.jpg|right|thumb|300px|The [[red supergiant]] star V838 Monocerotis, an example of one type of star which may become a black hole.]]
Stellar-mass black holes are said to form when stars more than ten times the mass of the Sun run out of fuel and die. The process of death occurs when stars that have fused the products of their own fusion into larger and larger elements, up to iron. The star then tries to fuse the iron core that forms as a result, but this does not produce enough energy to hold the outer layers of the star apart against the pull of gravity. When this happens, the iron core at the center of the star implodes in a supernova, and the outer layers of the star are blasted into space in one of the most energetic events in the universe—one star going out in a supernova can give off as much light as an entire galaxy. Not all supernovae result in black holes, but if the mass of the core is large enough, about 1.5-3.0 times the mass of the Sun (this value is termed the Tolman-Oppenheimer-Volkoff limit, and its value is not yet known to great precision), the leftover gravity of the shrinking core stalls the outward rush of the initial blast, and crushes the core into a point of infinite density: a black hole.

Extremely small black holes, with masses of around 1015 grams, have been theorized to have formed in the early universe. Any sufficiently small primordial black hole would be expected to evaporate within the lifetime of the universe, but the rate of evaporation is not currently known with any certainty.

At the opposite end of the spectrum, objects with the characteristics of supermassive black holes, millions or billions of times more massive than the sun, have been detected at the centers of many [[galaxies]], including our own [[Milky Way]]. In our galaxy, the hypothesized supermassive black hole is in the constellation Sagittarius, and is known as Sagittarius A* (pronounced "A star"). Based on the extraordinary angular velocity of stars near the galactic center, Sagittarius A* is believed to be on the order of two to three million solar masses. It is unknown how supermassive black holes form, though several models have been proposed. One hypothesis simply begins with a black hole of stellar mass which grows over the lifetime of the galaxy that surrounds it. Another proposal describes supermassive black holes as a natural, in fact nearly unavoidable, consequence of galactic formation. To date, no one theory of supermassive black hole formation is favored over all others.

==Methods of Observation==

Since black holes are literally invisible by traditional means of observation and so cannot be directly observed, their nature is determined from phenomena outside of the Schwarzschild radius. Scientists have located and observed objects theorized to be black holes through indirect means, such as the effect of their gravitational pull on nearby stars. Stars that are near black holes, e.g. by being part of a binary star system that contains one, show wobbles in their orbits similar to the tidal effects of the moon on Earth’s oceans. Wobble effects, however, cannot be used to conclusively prove the existence of a black hole. <ref>http://library.thinkquest.org/C007571/english/advance/english.htm</ref><ref>''Black Holes'' by Heather Cooper and Nigel Henbest (book)</ref> Scientists have also observed stellar objects which have density consistent with black holes<ref>http://amazing-space.stsci.edu/resources/explorations/blackholes/lesson/whatisit/history.html</ref>.

While matter and energy, even light, may not escape a black hole, Stephen Hawking has shown that when described by quantum mechanics, they should emit [[Hawking radiation]], which absent of an influx of mass-energy would lead to the evaporation of the black hole in a burst of gamma rays. Scientists are currently working to pick up one of these bursts, or the radiation itself, with any of several land- and space-based telescopes. However, the matter falling into black holes as well as the [[cosmic microwave background]] obscures the radiation and makes detection extremely difficult.

==Speculative Future Exploration==

Scientists have speculated that if a rotating black hole is large enough, a person could pass through the center of the ring-shaped singularity and possibly enter a wormhole. However, it would have to be a very large hole, for if it were not, the hypothetical astronaut would never survive to reach the event horizon due to tidal forces.

Matter coming close to the event horizon of a small black hole undergoes a process called spaghettification, a term coined by Stephen Hawking in his book ''A Brief History of Time'' to describe extraordinarily strong tidal forces. Because the mass at the center of the black hole is so dense, the gravitational pull on the near end of an object is much greater than the pull on the object’s far end. This causes the object to be stretched out in a way resembling a piece of spaghetti, and generally torn in two.

==White Holes==
Because the [[Quantitative Introduction to General Relativity|general relativity equations]] are symmetric with respect to time, one can take a negative square root instead of positive to yield an equation describing a hypothetical object which expels, rather than attracts, matter and energy.<ref>http://cosmology.berkeley.edu/Education/BHfaq.html#q10</ref> As this is the exact opposite of a black hole, it is called a '''white hole'''.

However, there is no evidence white holes actually exist. If they generate new matter and energy, this would violate the [[Law of the conservation of mass]]. Therefore, some scientists have proposed that matter falling into black holes goes through a [[wormhole]] to emerge at a white hole. While such wormholes are allowed by general relativity, they would be extremely unstable<ref>http://casa.colorado.edu/~ajsh/schww.html</ref>, and there is no evidence that they exist.

Scientists, who have been extremely eager to promote the idea of black hole existence, have shown a strong aversion to the white hole theory, even though, like a white hole, a black hole has never been observed directly. This may reflect an anti-creation bias on the part of scientists who are uncomfortable with the idea that matter and energy can be created outside of what scientific theories dictate should happen.

Dr. [[Russell Humphreys]] used a white hole in his model of the universe during [[Creation week]] to allow millions of years to pass in outer space while only three days passed on Earth.

==In Popular Culture==

Black holes have been a device in science fiction ever since their discovery. Many sci-fi books, movies, and television shows use black holes as a method of travel (see the Potential Future Exploration section above) or as a threat to a space-going vessel. In at least one season of the show ''Star Trek: the Next Generation'' by Gene Roddenberry, artificially created miniature black holes are used as power sources for spaceships and natural ones as incubators for the young of an alien race. Neither of these uses has much of a basis in reality, of course.

Contrary to popular myth, a black hole is not a cosmic vacuum cleaner. In other words, a one-solar-mass black hole is no better than any other one-solar-mass object (such as, for example, the Sun) at "sucking in" distant objects. However, a one-solar-mass black hole has the same amount of matter as any other one-solar-mass object but compressed into a much smaller space, making it impossible to move fast enough to leave a black hole once there. If a spaceship could land on a black hole, it would never be able to take off again.

The term "black hole" is also used as a metaphor for a place that it is hard to get out of, generally containing a high concentration of something unpleasant. Ex: "The inner city is a black hole of crime and drug use." Note that the Black Hole of Calcutta is ''not'' a reference to the celestial object; the name of the place predates the discovery of black holes in space and the Black Hole of Calcutta was a horrible underground prison in [[Calcutta]], India.

{{Relativity}}

==References==
{{reflist}}

*[http://imagine.gsfc.nasa.gov/docs/science/know_l2/black_holes.html Black Holes]
*[http://cosmology.berkeley.edu/Education/BHfaq.html Black Holes (Frequently Asked Questions)]

[[category: physics]]
[[Category:Relativity]]