Conservapedia - User contributions [en]

Black hole

2009-07-04T19:17:11Z

Inverness:

A '''black hole''' is a theoretical prediction of the [[theory of relativity]]. Evidence for Black holes is primality obtained by watching their effects on a nearby "normal" star. The black hole remains a popular topic for magazines, the science page of the [[New York Times]], and scientists on the cutting edge of astronomy and cosmology, as well as being a popular device in sci-fi due to its inherent "coolness factor".

[[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.]]
==Nature of a Black Hole==
A '''Black Hole''' is a theoretical mass with an infinitesimal volume, and therefore an infinite density. This gives them an escape velocity greater than the speed of light, meaning that light cannot escape from them due to their steep “gravity wells.” As this renders black holes invisible by traditional means of observation, scientists discover their locations 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. <ref>http://library.thinkquest.org/C007571/english/advance/english.htm</ref><ref>''Black Holes'' by Heather Cooper and Nigel Henbest (book)</ref> While matter and energy, even light, may not escape a black hole, Stephen Hawking has shown that 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 from the Big Bang obscures the radiation and inhibits its detection. The outer surface of a black hole is an event horizon, a non-material dimensional boundary, beyond which nothing can escape. The center of a black hole, where the mass exists, is called the singularity. The distance from the singularity to the event horizon is known as the Schwarzschild radius. All matter that falls into a black hole becomes part of the singularity, and as such is effectively destroyed.

==Origins of Black Holes==

Black holes form when supermassive stars more than ten times the mass of the Sun run out of fuel and die. The process of death occurs when supermassive 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.

==Properties of Black Holes==

Black holes only have three properties by which one differs from another: mass, electric charge, and spin. Mass describes the amount of matter in the singularity. It increases when matter falls into the hole, and decreases as the hole emits Hawking radiation and shrinks. Spin refers to whether the hole is stationary or spinning around an axis. While the singularity of a non-spinning hole is an infinitely small point, the singularity of a spinning hole is in the shape of an infinitely thin ring. Matter entering a spinning hole is first swirled around by the hole’s gravity, causing it to heat up and emit x-rays, which can be used to detect the hole. In the supermassive black holes at the centers of galaxies, some of the matter does not fall into the 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.

==Potential Future Exploration==

Scientists have speculated that if a spinning 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.

Matter coming close to the event horizon of a small black hole undergoes a process called spaghettification. Because the hole is so dense, its gravitational pull on the near end of an object is much greater than the hole’s 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.

==Scientific Understanding of Black Holes==

Schwarzschild discovered that black holes were possible under the theory of relativity. Albert Einstein tried to re-work the whole theory to eliminate the need for these singularities. However, Roger Penrose and Stephen Hawking proved the first of many Singularity Theorems, which states that singularities must form under certain conditions. This demonstrated that, rather than mathematical oddities, singularities are a fairly generic feature of realistic solutions to relativity. According to relativity, any mass with radius less than its Schwarzschild Radius is a black hole.

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.

==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.

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 literal hole in the ground in Calcutta, India.
==External links==

*[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)]

== References ==
<References/>

[[category: physics]]

Black hole

2009-07-04T19:16:32Z

Inverness:

A '''black hole''' is a theoretical prediction of the [[theory of relativity]]. Evidence for Black holes is primality obtained by watching their effects on a nearby "normal" star.. Nevertheless, the theoretical black hole remains a popular topic for magazines, the science page of the [[New York Times]], and scientists on the cutting edge of astronomy and cosmology, as well as being a popular device in sci-fi due to its inherent "coolness factor".

[[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.]]
==Nature of a Black Hole==
A '''Black Hole''' is a theoretical mass with an infinitesimal volume, and therefore an infinite density. This gives them an escape velocity greater than the speed of light, meaning that light cannot escape from them due to their steep “gravity wells.” As this renders black holes invisible by traditional means of observation, scientists discover their locations 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. <ref>http://library.thinkquest.org/C007571/english/advance/english.htm</ref><ref>''Black Holes'' by Heather Cooper and Nigel Henbest (book)</ref> While matter and energy, even light, may not escape a black hole, Stephen Hawking has shown that 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 from the Big Bang obscures the radiation and inhibits its detection. The outer surface of a black hole is an event horizon, a non-material dimensional boundary, beyond which nothing can escape. The center of a black hole, where the mass exists, is called the singularity. The distance from the singularity to the event horizon is known as the Schwarzschild radius. All matter that falls into a black hole becomes part of the singularity, and as such is effectively destroyed.

==Origins of Black Holes==

Black holes form when supermassive stars more than ten times the mass of the Sun run out of fuel and die. The process of death occurs when supermassive 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.

==Properties of Black Holes==

Black holes only have three properties by which one differs from another: mass, electric charge, and spin. Mass describes the amount of matter in the singularity. It increases when matter falls into the hole, and decreases as the hole emits Hawking radiation and shrinks. Spin refers to whether the hole is stationary or spinning around an axis. While the singularity of a non-spinning hole is an infinitely small point, the singularity of a spinning hole is in the shape of an infinitely thin ring. Matter entering a spinning hole is first swirled around by the hole’s gravity, causing it to heat up and emit x-rays, which can be used to detect the hole. In the supermassive black holes at the centers of galaxies, some of the matter does not fall into the 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.

==Potential Future Exploration==

Scientists have speculated that if a spinning 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.

Matter coming close to the event horizon of a small black hole undergoes a process called spaghettification. Because the hole is so dense, its gravitational pull on the near end of an object is much greater than the hole’s 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.

==Scientific Understanding of Black Holes==

Schwarzschild discovered that black holes were possible under the theory of relativity. Albert Einstein tried to re-work the whole theory to eliminate the need for these singularities. However, Roger Penrose and Stephen Hawking proved the first of many Singularity Theorems, which states that singularities must form under certain conditions. This demonstrated that, rather than mathematical oddities, singularities are a fairly generic feature of realistic solutions to relativity. According to relativity, any mass with radius less than its Schwarzschild Radius is a black hole.

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.

==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.

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 literal hole in the ground in Calcutta, India.
==External links==

*[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)]

== References ==
<References/>

[[category: physics]]

Mega year ago

2009-07-04T19:08:59Z

Inverness:

The Mega year ago, often abbreviated as Ma of Mya <ref>http://geomaps.wr.usgs.gov/socal/geology/geologic_history/images/geologic_time_scale.jpg</ref>, is a useful shorthand notation for long times that is more concise than scientific notation. The time for geological events such as the formation of a mountain is typically on the order of a few Ma.
==Use==
Instead of "trilobites went extinct 251 million years ago" <ref>http://www.trilobites.info/lasttrilos.htm</ref>, one would write "trilobites went extinct 251 Ma". The use of "Ma" avoids word repeats when writing papers.

[[Category:Terms]]

Australian Aborigines

2009-07-04T19:07:45Z

Inverness:

'''Aborigines''' are the main group of [[indigenous Australians]].

Aborigines were affected since [[English]] settlement in 1788. They have faced issues similar, but more extreme than the Native Americans, and currently make up only 2.4% of Australia's population. A substantial number of well-educated politicly liberal Americans don't know the Aborigines even existed, despite their inhabiting Australia long before the American Indians came to America.

==History==
The Aborigines came over the sea from Indonesia; however, long boat voyages were nearly impossible. Instead, they took advantage of lower sea levels and migrated short distances between islands. These "boats" could have been little more than well-made rafts. The people weren't completely isolated, as they had contact with sailers from the north for thousands of years.

Before white settlement of Australia, the distribution of the Aboriginal population was much the same as the modern population distribution, but at a much lower level. Today, the fertile regions with a temperate climate are dominated by the white Australian community. In most southern and eastern areas, Aborigines have either assimilated, died out, or been pushed out. Only in the central and northern parts of the country are there significant communities of Aborigines living on and in control of their traditional lands.

Most traditional Aborigines were nomadic over the range of their clan, however there are also several archaeological sites of permanent settlements in [[Victoria]].

Aborigines had no written language before contact with Europeans, but have a rich oral history. Their traditional creation stories are based on "The Dreamtime". Many of the modern Aboriginal communities in outback Australia are on the sites of Christian missions set up in the 1800s and early 1900s.

==Modern customs==
Since the 1980s indigenous Australians have been differentiated as “Australian Aborigines and Torres Strait Islanders” and more recently the acknowledgment of local tribal groups and [[language]]s has become normal. It has become customary for important public meetings and gatherings to begin by acknowledging “the customary owners of this land, the NAME people” where the local tribal name is given.

==Stolen Generation==
From the late 1800s through to the mid-1900s, many Aboriginal children were taken from their homes and placed in foster care arrangements, typically on [[Christian]] missions or state Government homes.
In the early 1990s Australians came to see this as being racist.

A prevailing view held that there was a hierarchy of human [[race]]s. This notion supposed that Northern Europeans were superior in civilisation and that Aborigines were inferior. According to this view, the increasing numbers of mixed-descent children in Australia, labelled as 'half-castes' (or alternatively 'crossbreeds', 'quadroons' and 'octoroons'), were seen by many to be a threat to racial purity. Many believe that in the first half of the twentieth century, this led to policies and legislation that resulted in the removal of children from their parents. The stated aim was to culturally assimilate mixed-descent people into contemporary Australian society. These children came to be called the Stolen Generation.

A [[Royal Commission]] was instituted by the [[Government of Australia]] under the auspices of the (Australian) Human Rights and Equal Opportunities Commission, headed by Sir [[Ronald Wilson]], a former Judge of the [[High Court of Australia]] and former President of the [[liberal]] [[Uniting Church in Australia]]. The commission took public testimony from around Australia, including visits to tribal lands, and its 1997 report ’’Bringing Them Home: Report of the National Inquiry into the Separation of Aboriginal and Torres Strait Islander Children from Their Families’’ has been seen to have re-shaped Australia’s internal race relations. The report suggested that considerable human rights abuses occurred as a result of the policies that led to the Stolen Generation, although responses of respective state and federal governments to the report's findings and recommendations have varied.

However, some people, including [[conservative]] columnist [[Andrew Bolt]], challenge the existence of the Stolen Generation. Bolt demanded that [[Robert Manne]], an outspoken advocate of the existence of the Stolen Generation, produce the names of ten children taken from their parents simply because they were Aboriginal or part Aboriginal. When Manne did produce a list, Bolt showed that the children were actually taken for the sake of their welfare. Bolt has further condemned the Stolen Generation concept for actually causing harm to Aboriginal children. He says that welfare officials are now too scared of being branded racist to take children who are in danger.

==Government apology==

On 13th of February, 2008 the [[Australia|Australian Government]] formally apologized to the Aboriginal People, and specifically to the Stolen Generation, for the actions of previous governments. The text of the apology, read by Prime Minister [[Kevin Rudd]], follows:

<blockquote>
Today we honour the Indigenous peoples of this land, the oldest continuing cultures in human history.

We reflect on their past mistreatment.

We reflect in particular on the mistreatment of those who were stolen generations - this blemished chapter in our nation's history.

The time has now come for the nation to turn a new page in Australia's history by righting the wrongs of the past and so moving forward with confidence to the future.

We apologise for the laws and policies of successive Parliaments and governments that have inflicted profound grief, suffering and loss on these our fellow Australians.

We apologise especially for the removal of Aboriginal and Torres Strait Islander children from their families, their communities and their country.

For the pain, suffering and hurt of these stolen generations, their descendants and for their families left behind, we say sorry.

To the mothers and the fathers, the brothers and the sisters, for the breaking up of families and communities, we say sorry.

And for the indignity and degradation thus inflicted on a proud people and a proud culture, we say sorry.

We the Parliament of Australia respectfully request that this apology be received in the spirit in which it is offered as part of the healing of the nation.

For the future we take heart; resolving that this new page in the history of our great continent can now be written.

We today take this first step by acknowledging the past and laying claim to a future that embraces all Australians.

A future where this Parliament resolves that the injustices of the past must never, never happen again.

A future where we harness the determination of all Australians, Indigenous and non-Indigenous, to close the gap that lies between us in life expectancy, educational achievement and economic opportunity.

A future where we embrace the possibility of new solutions to enduring problems where old approaches have failed.

A future based on mutual respect, mutual resolve and mutual responsibility.

A future where all Australians, whatever their origins, are truly equal partners, with equal opportunities and with an equal stake in shaping the next chapter in the history of this great country, Australia.

</blockquote>

==Aborigines in the media==
Various Australian films have significantly changed perceptions of Aborigines.
* ''Jedda'' (1955) by the Australian filmmaker Charles Chauvel. The film is most notable for being the first to star two Aboriginal actors (Robert Tudawali and Ngarla Kunoth) in the leading roles, and also to be the first Australian film shot in color.
* ''Storm Boy'' (1976) which tells of the interaction between an Anglo boy and a local Aborigine.
* ''Rabbit-Proof Fence'' (2002) is an Australian film based on the book ''Follow The Rabbit Proof Fence'' by Doris Pilkington Garimara. It concerns the author's mother, and two other young mixed-race Aboriginal girls, who ran away from a residential school that is located in Moore River Native Settlement, north of [[Perth]], [[Western Australia]], in which they were placed in 1931, in order to return to their Aboriginal families. The film follows the girls as they trek/walk for nine weeks along 2,400km (1,500 miles) of the Australian [[rabbit]]-proof fence to return to their community at Jigalong.
* ''Ten Canoes'' (2006) by Rolf de Heer. The film is narrated in English by David Gulpilil; all protagonists speak in indigenous languages, with English subtitles.

David Gulpilil is recognized as a very important Australian Aboriginal actor, whose work has changed perceptions of Aborigines. His films have been:

* ''Walkabout'' (1971)
* ''Storm Boy'' (1976)
* ''The Last Wave'' (1977)
* ''The Right Stuff'' (1983)
* ''[[Crocodile Dundee]]'' (1986)
* ''Rabbit-Proof Fence'' (2002)
* ''The Tracker'' (2002)
* ''The Proposition'' (2005)
* ''Ten Canoes'' (2006)

Stan Grant is an Aboriginal television personality who had international recognition as a presenter for [[CNN]] in [[Bejing]], [[China]] in the mid-2000s.

== External links ==

* [http://www.hreoc.gov.au/social_justice/bth_report/index.html Bringing them home: The 'Stolen Children' report (1997)], Human Rights and Equal Opportunity Commission.
* Bolt, Andrew, [http://blogs.news.com.au/heraldsun/andrewbolt/index.php/heraldsun/comments/stolen_generations_my_writers_festival_speech/ Stolen generations: My Melbourne Writers’ Festival speech], 5th September, 2006.
* Bolt, Andrew, [http://blogs.news.com.au/heraldsun/andrewbolt/index.php/heraldsun/comments/fisking_mannes_column/ Fisking Manne’s column], 9th December, 2006 (reply to ''The Cruelty of Denial'')
* Bolt, Andrew, [http://blogs.news.com.au/heraldsun/andrewbolt/index.php/heraldsun/comments/another_stolen_life/ Another stolen life], 19th September, 2006 (Bolt claims as a case of an aboriginal child in danger and ''not'' removed by authorities because of concerns over racism)
* Bolt, Andrew, [http://blogs.news.com.au/heraldsun/andrewbolt/index.php/heraldsun/comments/column_truth_is_what_was_stolen/ Truth is what was stolen], ''Herald Sun'', 8th February, 2008.
* Manne, Robert, [http://www.theage.com.au/ed_docs/manne1.pdf Stolen Generations Debate, with Andrew Bolt], 3rd September, 2006.
* Manne, Robert, [http://www.theage.com.au/news/robert-manne/the-cruelty-of-denial/2006/09/08/1157222325367.html?page=fullpage#contentSwap1 The Cruelty of Denial], The Age, 9th December, 2006.

== See also ==
* [[Great Flood]] (which mentions some aboriginal flood stories)
[[Category:Australia]]

Indigenous Australians

2009-05-15T17:35:27Z

Inverness:

The '''indigenous peoples of Australia''' are broadly divided into two or three groups. The largest group is the [[Australian Aborigines]] who traditionally occupied most of the Australian mainland and some offshore islands. The second group is the [[Torres Strait Islanders]] who traditionally occupied the islands of [[Torres Strait]] and part of [[Cape York Peninsula]]. Sometimes, a third group is used, separating the [[Tasmanian Aborigines]] from the mainland Aborigines. All of the indigenous peoples have dark skin, although how dark depends on where they are from.

The Australian Aborigines are further divided into about 300 separate language groups, sometimes called "nations". A map of the tribal distribution before the arrival of white settlers can be found here [http://www.samuseum.sa.gov.au/page/default.asp?site=2&page=TIN_Tribal]. In Australia, indigenous people as a broad group are usually called "Aboriginal and Torres Strait Islanders" by the government.

The Indigenous Australians lived in [[Australia]] as far as 50 000 years ago. Genetic evidence suggests that multiple waves of people migrated into Australia over tens of thousands of years before [[Europe]]an colonization. [https://genographic.nationalgeographic.com/genographic/lan/en/atlas.html] Even between these "waves" the Aborigines weren't completely isolated, there was migration back and forth over the islands, allowing small levels of exchange with [[Melanesia]]. With few exceptions, complete isolation of an ethnic group is a fallacy. [http://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf]

[[Category:Australia]]

Abirigine

2009-05-15T17:34:30Z

Inverness: Redirected page to Indigenous Australians

#REDIRECT [[Indigenous Australians]]

Mega year ago

2009-05-10T20:25:03Z

Inverness:

The Mega year ago, often abbreviated as Ma of Mya <ref>http://geomaps.wr.usgs.gov/socal/geology/geologic_history/images/geologic_time_scale.jpg</ref>, is a useful shorthand notation for long times more concise than scientific notation. The time for geological events such as the formation of a mountain is typically on the order of a few Ma.
==Use==
Instead of "trilobites went extinct 251 million years ago" <ref>http://www.trilobites.info/lasttrilos.htm</ref>, one would write "trilobites went extinct 251 Ma". The use of "Ma" avoids word repeats when writing papers.

[[Category:Terms]]

Indigenous Australians

2009-05-03T20:14:50Z

Inverness:

The '''indigenous peoples of Australia''' are broadly divided into two or three groups. The largest group is the [[Australian Aborigines]] who traditionally occupied most of the Australian mainland and some offshore islands. The second group is the [[Torres Strait Islanders]] who traditionally occupied the islands of [[Torres Strait]] and part of [[Cape York Peninsula]]. Sometimes, a third group is used, separating the [[Tasmanian Aborigines]] from the mainland Aborigines. All of the indigenous peoples have dark skin, although how dark depends on where they are from.

The Australian Aborigines are further divided into about 300 separate language groups, sometimes called "nations". A map of the tribal distribution before the arrival of white settlers can be found here [http://www.samuseum.sa.gov.au/page/default.asp?site=2&page=TIN_Tribal]. In Australia, indigenous people as a broad group are usually called "Aboriginal and Torres Strait Islanders" by the government.

The Indigenous Australians lived in [[Australia]] as far as 50 000 years ago. New genetic evidence suggests that multiple waves of people migrated into Australia over tens of thousands of years before [[Europe]]an colonization. [https://genographic.nationalgeographic.com/genographic/lan/en/atlas.html] Even between these "waves" the Aboriginies weren't completely isolated, there was migration back and forth over the islands, allowing small levels of exchange with [[Melanesia]]. WIth few exceptions, complete isolation of an ethnic group is a fallacy. [http://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf]

[[Category:Australia]]

Indigenous Australians

2009-05-03T20:14:23Z

Inverness:

The '''indigenous peoples of Australia''' are broadly divided into two or three groups. The largest group is the [[Australian Aborigines]] who traditionally occupied most of the Australian mainland and some offshore islands. The second group is the [[Torres Strait Islanders]] who traditionally occupied the islands of [[Torres Strait]] and part of [[Cape York Peninsula]]. Sometimes, a third group is used, separating the [[Tasmanian Aborigines]] from the mainland Aborigines. All of the indigenous peoples have dark skin, although how dark depends on where they are from.

The Australian Aborigines are further divided into about 300 separate language groups, sometimes called "nations". A map of the tribal distribution before the arrival of white settlers can be found here [http://www.samuseum.sa.gov.au/page/default.asp?site=2&page=TIN_Tribal]. In Australia, indigenous people as a broad group are usually called "Aboriginal and Torres Strait Islanders" by the government.

The Aboriginies, or more correctly termed "Indigenous Australians" lived in [[Australia]] as far as 50 000 years ago. New genetic evidence suggests that multiple waves of people migrated into Australia over tens of thousands of years before [[Europe]]an colonization. [https://genographic.nationalgeographic.com/genographic/lan/en/atlas.html] Even between these "waves" the Aboriginies weren't completely isolated, there was migration back and forth over the islands, allowing small levels of exchange with [[Melanesia]]. WIth few exceptions, complete isolation of an ethnic group is a fallacy. [http://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf]

[[Category:Australia]]

Australian Aborigine

2009-05-03T19:57:10Z

Inverness: Redirected page to Indigenous Australians

#REDIRECT [[Indigenous Australians]]

Australian Aborigine

2009-05-03T19:55:35Z

Inverness: Redirected page to Indigenous Austrailians

#REDIRECT [[Indigenous Austrailians]]

Aboriginies

2009-05-03T19:53:11Z

Inverness: Redirected page to Aboriginie

#REDIRECT [[Aboriginie]]

Australian Aborigine

2009-05-03T19:51:45Z

Inverness:

The Aboriginies, or more correctly termed "Indigenous Australians" lived in [[Australia]] as far as 50 000 years ago. New genetic evidence suggests that multiple waves of people migrated into Australia over tens of thousands of years before [[Europe]]an colonization. [https://genographic.nationalgeographic.com/genographic/lan/en/atlas.html] Even between these "waves" the Aboriginies weren't completely isolated, there was migration back and forth over the islands, allowing small levels of exchange with [[Melanesia]]. In general, complete ethnic isolation of any group for thousands of years is a fallacy.[http://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf]

When the Europeans colonized Australia, the indigenous people and culture declined drastically. They currently have high levels of [[smoking]] as Europeans introduced tobacco to their culture. [http://www.nsma.org.au/facts/aborignl.htm]
[[category:Australia]]

Mega year ago

2009-05-02T17:47:12Z

Inverness: /* Use */

The Mega year ago, often abbreviated as Ma of Mya <ref>http://geomaps.wr.usgs.gov/socal/geology/geologic_history/images/geologic_time_scale.jpg</ref>, is a useful shorthand notation for long times more concise than scientific notation.
==Use==
Instead of "trilobites went extinct 251 million years ago" <ref>http://www.trilobites.info/lasttrilos.htm</ref>, one would write "trilobites went extinct 251 Ma". The use of "Ma" avoids word repeats when writing papers.

Trilobite

2009-05-02T17:46:57Z

Inverness: /* Evolution and extinction */

[[Image:Trilobites.jpg|right|thumb|200px|A variety of Trilobites]]'''Trilobites''' are an extinct form of [[arthropod]]. They came in a wide variety of sizes ranging from being under a millimeter long to being over two feet in length.
==Evolution and extinction==
Trilobites first appeared some 600 [[mega year ago|Ma]]. during the Cambrian period. They diversified into many orders, and over a (relatively) short time scale disappeared completly about 250 Ma<ref>http://www.trilobites.info/trends.htm</ref>. The causes of the extinction are not fully clear <ref>http://www.trilobites.info/lasttrilos.htm</ref>.

==Morphology==
They belonged to the phylum Arthropodal (joint-footed), a phylum which to this day represents the most successful in terms of numbers (78%) of all animal life forms, including crabs, centipedes, spiders, shrimps and insects. The name Trilobite, meaning three lobed one, refers to the three longitudinal lobes across the head (cephalon). The entire bodies were also divided into three: the head (cephalon), thorax (chest) made of up to 30 segments and the tail (pygidium). Underneath and rarely preserved are three pairs of legs for the head and paired legs for each pleural groove. Trilobites are the earliest known animal to possess vision. Some possessed [[eye]]s and some seem to have no eyes at all, while others possessed beautiful compound eyes capable of 360 degree vision.<ref>http://www.trilobite.com</ref>

==In culture==
The trilobite is [[Ohio]]'s official state [[fossil]].<ref>Ohio Revised Code 5.071</ref>

==References==
<references />

==Links==
*[http://www.trilobites.info/ Guide to Trilobites]
*[http://www.westernta.com/ Western Trilobite Association]

[[Category:Invertebrates]]

Trilobite

2009-05-02T17:46:42Z

Inverness: /* Evolution and extinction */

[[Image:Trilobites.jpg|right|thumb|200px|A variety of Trilobites]]'''Trilobites''' are an extinct form of [[arthropod]]. They came in a wide variety of sizes ranging from being under a millimeter long to being over two feet in length.
==Evolution and extinction==
Trilobites first appeared some 600 [[mega year ago}Ma]]. during the Cambrian period. They diversified into many orders, and over a (relatively) short time scale disappeared completly about 250 Ma<ref>http://www.trilobites.info/trends.htm</ref>. The causes of the extinction are not fully clear <ref>http://www.trilobites.info/lasttrilos.htm</ref>.

==Morphology==
They belonged to the phylum Arthropodal (joint-footed), a phylum which to this day represents the most successful in terms of numbers (78%) of all animal life forms, including crabs, centipedes, spiders, shrimps and insects. The name Trilobite, meaning three lobed one, refers to the three longitudinal lobes across the head (cephalon). The entire bodies were also divided into three: the head (cephalon), thorax (chest) made of up to 30 segments and the tail (pygidium). Underneath and rarely preserved are three pairs of legs for the head and paired legs for each pleural groove. Trilobites are the earliest known animal to possess vision. Some possessed [[eye]]s and some seem to have no eyes at all, while others possessed beautiful compound eyes capable of 360 degree vision.<ref>http://www.trilobite.com</ref>

==In culture==
The trilobite is [[Ohio]]'s official state [[fossil]].<ref>Ohio Revised Code 5.071</ref>

==References==
<references />

==Links==
*[http://www.trilobites.info/ Guide to Trilobites]
*[http://www.westernta.com/ Western Trilobite Association]

[[Category:Invertebrates]]

Trilobite

2009-05-02T17:46:20Z

Inverness:

[[Image:Trilobites.jpg|right|thumb|200px|A variety of Trilobites]]'''Trilobites''' are an extinct form of [[arthropod]]. They came in a wide variety of sizes ranging from being under a millimeter long to being over two feet in length.
==Evolution and extinction==
Trilobites first appeared some 600 [[Ma| mega year ago]]. during the Cambrian period. They diversified into many orders, and over a (relatively) short time scale disappeared completly about 250 Ma<ref>http://www.trilobites.info/trends.htm</ref>. The causes of the extinction are not fully clear <ref>http://www.trilobites.info/lasttrilos.htm</ref>.

==Morphology==
They belonged to the phylum Arthropodal (joint-footed), a phylum which to this day represents the most successful in terms of numbers (78%) of all animal life forms, including crabs, centipedes, spiders, shrimps and insects. The name Trilobite, meaning three lobed one, refers to the three longitudinal lobes across the head (cephalon). The entire bodies were also divided into three: the head (cephalon), thorax (chest) made of up to 30 segments and the tail (pygidium). Underneath and rarely preserved are three pairs of legs for the head and paired legs for each pleural groove. Trilobites are the earliest known animal to possess vision. Some possessed [[eye]]s and some seem to have no eyes at all, while others possessed beautiful compound eyes capable of 360 degree vision.<ref>http://www.trilobite.com</ref>

==In culture==
The trilobite is [[Ohio]]'s official state [[fossil]].<ref>Ohio Revised Code 5.071</ref>

==References==
<references />

==Links==
*[http://www.trilobites.info/ Guide to Trilobites]
*[http://www.westernta.com/ Western Trilobite Association]

[[Category:Invertebrates]]

Mega year ago

2009-05-02T17:35:29Z

Inverness: Created page with 'The Mega year ago, often abbreviated as Ma of Mya <ref>http://geomaps.wr.usgs.gov/socal/geology/geologic_history/images/geologic_time_scale.jpg</ref>, is a useful shorthand notat...'

The Mega year ago, often abbreviated as Ma of Mya <ref>http://geomaps.wr.usgs.gov/socal/geology/geologic_history/images/geologic_time_scale.jpg</ref>, is a useful shorthand notation for long times more concise than scientific notation.
==Use==
Instead of "trilobites went extinct 291 million years ago" <ref>http://www.trilobites.info/lasttrilos.htm</ref>, one would write "trilobites went extinct 291 Ma". The use of "Ma" avoids word repeats when writing papers.

Nebula

2009-05-02T17:26:20Z

Inverness:

A '''nebula''', from the [[Latin]] word for ''[[cloud]]'', is a cloud of interstellar [[dust]] and [[gas | gases]]. <ref>http://fusedweb.pppl.gov/CPEP/Chart_Pages/5.Plasmas/Nebula.html</ref>. Nebulae have been observed both within the [[Milky Way]] [[galaxy]] and in other galaxies. These large clouds of mostly hydrogen gas can form stars an planets. Our solar system formed about 4.6 billion years ago from a nebula. <ref>http://www.windows.ucar.edu/tour/our_solar_system/formation.html</ref>

==External Links==
[http://www.godandscience.org/love/tourjs.html Some spectacular pictures from the Hubble Telescope, which include many nebulae]

==References==
<references/>
[[Category:Astronomy]]

Nebula

2009-05-02T17:26:01Z

Inverness:

A '''nebula''', from the [[Latin]] word for ''[[cloud]]'', is a cloud of interstellar [[dust]] and [[gas | gases]]. <ref>http://fusedweb.pppl.gov/CPEP/Chart_Pages/5.Plasmas/Nebula.html</ref>. Nebulae have been observed both within the [[Milky Way]] [[galaxy]] and in other galaxies. These large clouds of mostly hydrogen gas can form stars an planets. Our solar system formed about 4.6 billion years ago. <ref>http://www.windows.ucar.edu/tour/our_solar_system/formation.html</ref>

==External Links==
[http://www.godandscience.org/love/tourjs.html Some spectacular pictures from the Hubble Telescope, which include many nebulae]

==References==
<references/>
[[Category:Astronomy]]

Nebula

2009-05-02T17:25:19Z

Inverness:

A '''nebula''', from the [[Latin]] word for ''[[cloud]]'', is a cloud of interstellar [[dust]] and [[gas | gases]]. <ref>http://fusedweb.pppl.gov/CPEP/Chart_Pages/5.Plasmas/Nebula.html</ref>. Nebulae have been observed both within the [[Milky Way]] [[galaxy]] and in other galaxies. These large clouds of mostly hydrogen gas can form stars, as likely happened to our solar system about 4.6 billion years ago. <ref>http://www.windows.ucar.edu/tour/our_solar_system/formation.html</ref>

==External Links==
[http://www.godandscience.org/love/tourjs.html Some spectacular pictures from the Hubble Telescope, which include many nebulae]

==References==
<references/>
[[Category:Astronomy]]

Nebula

2009-05-02T17:24:27Z

Inverness:

A '''nebula''', from the [[Latin]] word for ''[[cloud]]'', is a cloud of interstellar [[dust]] and [[gas | gases]]. <ref>http://fusedweb.pppl.gov/CPEP/Chart_Pages/5.Plasmas/Nebula.html</ref>. Nebulae have been observed both within the [[Milky Way]] [[galaxy]] and in other galaxies. These large clouds of mostly hydrogen gas can form stars, as likely happened to our solar system about 4.6 billion years ago. [[http://www.windows.ucar.edu/tour/our_solar_system/formation.html]]

==External Links==
[http://www.godandscience.org/love/tourjs.html Some spectacular pictures from the Hubble Telescope, which include many nebulae]

==References==
<references/>
[[Category:Astronomy]]

Carbon dating

2009-05-01T02:49:30Z

Inverness: /* Widespread misunderstandings */

'''Carbon dating''', or carbon-14 dating, is a method for comparing the ages of organic materials such as bones or artifacts made from anything that once lived.
Unlike many other radiometric dating methods, carbon dating has been calibrated for historical periods and within that range can give reliable results.

== Principles ==

[[Image:C-14decay.JPG|framed|The first-order decay curve of carbon-14 based on the half-life of 5730 years.]]
The technique is based on comparing the levels of 14C and 12C [[isotope]]s in the sample.
14C is produced in the atmosphere by cosmic ray [[neutron]]s replacing a [[proton]] in [[nitrogen]] (14N), producing 14C.<ref name="TH">Higham, Thomas, [http://www.c14dating.com/int.html Introduction], Radiocarbon web-info.</ref>

14C is unstable and [[radioactive decay|decays]] back to 14N, at the rate of 50% every 5,730 years (so after 11,460 years 25% will be left, after 17,190 years 12.5% will be left, and so on).

In the meantime, however, the 14C will combine with [[oxygen]] in the atmosphere to form [[carbon dioxide]], which enters the food chain via [[photosynthesis]] in plants.<ref name="TH" />
By this means, most living things also have 14C and 12C in the same ratio as in the atmosphere.
This ratio is about one 14C atom for every 1,000,000,000,000 12C atoms.<ref name="TH" />

However, when the sample dies, it stops ingesting 14C, so as the 14C decays to 14N, the ratio of 14C and 12C changes.
This ratio of 14C to 12C is measured and a calculation turns the measurement into a figure representing how long ago the sample died.

Depending on the method used to measure the 14C, after about 50,000 years or so there is not enough left to measure, although advanced techniques can possibly stretch that to 100,000 years.<ref>Nave, R., [http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/cardat.html Carbon Dating], Georgia State University.</ref>
This then becomes the maximum age that can theoretically be derived by this method.

Therefore, any sample with too little 14C to measure must, in theory, be older than 50,000 to 100,000 years, and it is not possible to determine how much older.
Similarly, any sample with measurable 14C must be younger than 50,000 to 100,000 years, assuming that adequate precautions have been taken to eliminate contamination.

== Limits of Carbon Dating ==

Carbon dating, like other [[radiometric dating]] methods, requires certain assumptions that cannot be scientifically proved.
These include the starting conditions, the constancy of the rate of decay, and that no material has left or entered the sample.

=== Calibration ===

Unlike other radiometric dating techniques where it is not possible to [[calibration|calibrate]] the method against historically-known dates, limited calibration is possible for carbon dating.
That is, samples with dates known from historical records can be used to check the accuracy of the method.
Despite this, however, caution is still necessary in accepting dates derived from carbon dating.

Claims have been made of the method being calibrated back to 10,000 years using [[dendrochronology]],<ref name="TH" /> however these older dates derived via dendrochronology have themselves been derived with the assistance of carbon dating<ref>Batten, Don, [http://creationontheweb.com/content/view/2441 Tree ring dating (dendrochronology)] (Creation Ministries International).</ref>, making this circular reasoning.

=== Variable intake ===

Not all living things do have 14C:12C ratios the same as the atmosphere.
{{QuoteBox|...various plants have differing abilities to exclude significant proportions of the C-14 in their intake. This varies with environmental conditions as well. The varying rates at which C-14 is excluded in plants also means that the apparent age of a living animal may be affected by an animal's diet. An animal that ingested plants with relatively low C-14 proportions would be dated older than their true age."<ref>Nondestructive Testing (NDT) Resource Center, [http://www.ndt-ed.org/EducationResources/CommunityCollege/Radiography/Physics/carbondating.htm Carbon-14 Dating"]</ref>}}

=== Atmospheric variability ===

The method relies on the assumption that we know how much 14C is in the atmosphere, but this has been known to change.
Nuclear testing since the 1950s has resulted in a large increase in the amount of 14C in the atmosphere, but because the levels have been measured since the 1950s, calculations can be adjusted for these changing levels, meaning that dating of recent samples is possible.<ref name="K12">Higham, Thomas? [http://www.c14dating.com/k12.html K-12] Radiocarbon web-info.</ref>

However, atmospheric levels are also known to have changed since the start of the [[industrial revolution]], making dating items from this period more difficult.<ref name="K12" />

Dating laboratories do not make any allowance for the change in atmospheric levels that would have occurred as a result of [[Great Flood|Noah's Flood]].
This means that radio-carbon dates cannot be used to prove that the Flood did not occur, because it ''assumes'' that it did not occur.<ref>Batten, Don, (Ed.) [http://www.creationontheweb.com/images/pdfs/cabook/chapter4.pdf What about carbon dating?] Chapter 4 of the ''Creation Answers Book''.</ref>

=== Solar-Earth effect ===

Scientists at Brookhaven National Laboratory and the Physikalish-Technische-Bundesandstalt in Germany have reported "unexplained periodic fluctuations in the [nuclear] decay rates of Si-32 and Ra-226... strongly correlated in time, not only with each other, but also with the distance between the Earth and the Sun." It is likely that similar discrepancies and fluctuations occur with other nuclear decay rates, such as that of 14C. It remains for scientists to perform experiments to explore these emerging issues. <ref>[http://arxiv.org/abs/0808.3283 Evidence for Correlations Between Nuclear Decay Rates and Earth-Sun Distance], Jenkins et al. Abstract: Unexplained periodic fluctuations in the decay rates of Si-32 and Ra-226 have been reported by groups at Brookhaven National Laboratory (Si-32), and at the Physikalisch-Technische-Bundesandstalt in Germany (Ra-226). We show from an analysis of the raw data in these experiments that the observed fluctuations are strongly correlated in time, not only with each other, but also with the distance between the Earth and the Sun. Some implications of these results are also discussed, including the suggestion that discrepancies in published half-life determinations for these and other nuclides may be attributable in part to differences in solar activity during the course of the various experiments, or to seasonal variations in fundamental constants.</ref>

== History ==

Carbon Dating was developed by [[Willard F. Libby]] and his team of scientists at the [[University of Chicago]] in 1949.<ref name="TH" />
They initially measured the 'half-life' (a term that Libby coined)<ref name="TH" /> as 5568±30 years, and this became known as the ''Libby half-life''.<ref name="TH" />
It was later measured more accurately to be 5730±40 years, now known as the ''Cambridge half-life''.<ref name="TH" />

== Widespread misunderstandings ==
Carbon dating is not used to measure beyond thousands of years, despite some claiming that carbon dating is used to date dinosaur fossils and other things claimed to be millions of years old. Even those who understand carbon dating's limits may believe that radioactive carbon "runs out" after a set amount of time.

The maximum age depends upon the sensitivity of the equipment. The amount never drops to zero (ignoring the finite amount of atoms), it just approaches zero as an [[asymptote]]. If the equipment can accurately measure a concentration of 1/8'th the natural sample, than it can measure items up to three half-lives old. A more sensitive instrument that can detect 1/16'th of normal carbon-14 can date to 4 half lives old.

==See also==
*[[Martin Kamen]]

== References ==

<references/>

[[Category:Chronology]][[Category:Earth Sciences]]

Carbon dating

2009-05-01T02:49:13Z

Inverness: /* Widespread misunderstandings */

'''Carbon dating''', or carbon-14 dating, is a method for comparing the ages of organic materials such as bones or artifacts made from anything that once lived.
Unlike many other radiometric dating methods, carbon dating has been calibrated for historical periods and within that range can give reliable results.

== Principles ==

[[Image:C-14decay.JPG|framed|The first-order decay curve of carbon-14 based on the half-life of 5730 years.]]
The technique is based on comparing the levels of 14C and 12C [[isotope]]s in the sample.
14C is produced in the atmosphere by cosmic ray [[neutron]]s replacing a [[proton]] in [[nitrogen]] (14N), producing 14C.<ref name="TH">Higham, Thomas, [http://www.c14dating.com/int.html Introduction], Radiocarbon web-info.</ref>

14C is unstable and [[radioactive decay|decays]] back to 14N, at the rate of 50% every 5,730 years (so after 11,460 years 25% will be left, after 17,190 years 12.5% will be left, and so on).

In the meantime, however, the 14C will combine with [[oxygen]] in the atmosphere to form [[carbon dioxide]], which enters the food chain via [[photosynthesis]] in plants.<ref name="TH" />
By this means, most living things also have 14C and 12C in the same ratio as in the atmosphere.
This ratio is about one 14C atom for every 1,000,000,000,000 12C atoms.<ref name="TH" />

However, when the sample dies, it stops ingesting 14C, so as the 14C decays to 14N, the ratio of 14C and 12C changes.
This ratio of 14C to 12C is measured and a calculation turns the measurement into a figure representing how long ago the sample died.

Depending on the method used to measure the 14C, after about 50,000 years or so there is not enough left to measure, although advanced techniques can possibly stretch that to 100,000 years.<ref>Nave, R., [http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/cardat.html Carbon Dating], Georgia State University.</ref>
This then becomes the maximum age that can theoretically be derived by this method.

Therefore, any sample with too little 14C to measure must, in theory, be older than 50,000 to 100,000 years, and it is not possible to determine how much older.
Similarly, any sample with measurable 14C must be younger than 50,000 to 100,000 years, assuming that adequate precautions have been taken to eliminate contamination.

== Limits of Carbon Dating ==

Carbon dating, like other [[radiometric dating]] methods, requires certain assumptions that cannot be scientifically proved.
These include the starting conditions, the constancy of the rate of decay, and that no material has left or entered the sample.

=== Calibration ===

Unlike other radiometric dating techniques where it is not possible to [[calibration|calibrate]] the method against historically-known dates, limited calibration is possible for carbon dating.
That is, samples with dates known from historical records can be used to check the accuracy of the method.
Despite this, however, caution is still necessary in accepting dates derived from carbon dating.

Claims have been made of the method being calibrated back to 10,000 years using [[dendrochronology]],<ref name="TH" /> however these older dates derived via dendrochronology have themselves been derived with the assistance of carbon dating<ref>Batten, Don, [http://creationontheweb.com/content/view/2441 Tree ring dating (dendrochronology)] (Creation Ministries International).</ref>, making this circular reasoning.

=== Variable intake ===

Not all living things do have 14C:12C ratios the same as the atmosphere.
{{QuoteBox|...various plants have differing abilities to exclude significant proportions of the C-14 in their intake. This varies with environmental conditions as well. The varying rates at which C-14 is excluded in plants also means that the apparent age of a living animal may be affected by an animal's diet. An animal that ingested plants with relatively low C-14 proportions would be dated older than their true age."<ref>Nondestructive Testing (NDT) Resource Center, [http://www.ndt-ed.org/EducationResources/CommunityCollege/Radiography/Physics/carbondating.htm Carbon-14 Dating"]</ref>}}

=== Atmospheric variability ===

The method relies on the assumption that we know how much 14C is in the atmosphere, but this has been known to change.
Nuclear testing since the 1950s has resulted in a large increase in the amount of 14C in the atmosphere, but because the levels have been measured since the 1950s, calculations can be adjusted for these changing levels, meaning that dating of recent samples is possible.<ref name="K12">Higham, Thomas? [http://www.c14dating.com/k12.html K-12] Radiocarbon web-info.</ref>

However, atmospheric levels are also known to have changed since the start of the [[industrial revolution]], making dating items from this period more difficult.<ref name="K12" />

Dating laboratories do not make any allowance for the change in atmospheric levels that would have occurred as a result of [[Great Flood|Noah's Flood]].
This means that radio-carbon dates cannot be used to prove that the Flood did not occur, because it ''assumes'' that it did not occur.<ref>Batten, Don, (Ed.) [http://www.creationontheweb.com/images/pdfs/cabook/chapter4.pdf What about carbon dating?] Chapter 4 of the ''Creation Answers Book''.</ref>

=== Solar-Earth effect ===

Scientists at Brookhaven National Laboratory and the Physikalish-Technische-Bundesandstalt in Germany have reported "unexplained periodic fluctuations in the [nuclear] decay rates of Si-32 and Ra-226... strongly correlated in time, not only with each other, but also with the distance between the Earth and the Sun." It is likely that similar discrepancies and fluctuations occur with other nuclear decay rates, such as that of 14C. It remains for scientists to perform experiments to explore these emerging issues. <ref>[http://arxiv.org/abs/0808.3283 Evidence for Correlations Between Nuclear Decay Rates and Earth-Sun Distance], Jenkins et al. Abstract: Unexplained periodic fluctuations in the decay rates of Si-32 and Ra-226 have been reported by groups at Brookhaven National Laboratory (Si-32), and at the Physikalisch-Technische-Bundesandstalt in Germany (Ra-226). We show from an analysis of the raw data in these experiments that the observed fluctuations are strongly correlated in time, not only with each other, but also with the distance between the Earth and the Sun. Some implications of these results are also discussed, including the suggestion that discrepancies in published half-life determinations for these and other nuclides may be attributable in part to differences in solar activity during the course of the various experiments, or to seasonal variations in fundamental constants.</ref>

== History ==

Carbon Dating was developed by [[Willard F. Libby]] and his team of scientists at the [[University of Chicago]] in 1949.<ref name="TH" />
They initially measured the 'half-life' (a term that Libby coined)<ref name="TH" /> as 5568±30 years, and this became known as the ''Libby half-life''.<ref name="TH" />
It was later measured more accurately to be 5730±40 years, now known as the ''Cambridge half-life''.<ref name="TH" />

== Widespread misunderstandings ==
Carbon dating is not used to measure beyond thousands of years, despite some claiming that carbon dating is used to date dinosaur fossils and other things claimed to be millions of years old. Even those who understand carbon dating's limits may believe that radioactive carbon "runs out" after a set amount of time.

The maximum age depends upon the sensitivity of the equipment. The amount never drops to zero (ignoring the finite amount of atoms), it just approaches zero as an [asymptote]. If the equipment can accurately measure a concentration of 1/8'th the natural sample, than it can measure items up to three half-lives old. A more sensitive instrument that can detect 1/16'th of normal carbon-14 can date to 4 half lives old.

==See also==
*[[Martin Kamen]]

== References ==

<references/>

[[Category:Chronology]][[Category:Earth Sciences]]

Australian Aborigine

2009-05-01T02:32:23Z

Inverness:

The Aboriginies, or more correctly termed "Indigenous Australians" lived in Austrailia as far as 50 000 years ago. New genetic evidence suggests that multiple waves of people migrated into Australia over tens of thousands of years before European colonization. [https://genographic.nationalgeographic.com/genographic/lan/en/atlas.html] They weren't completely isolated, there was migration back and forth over the islands, allowing small levels of exchange with Melanesia. In general, complete ethnic isolation of any group for thousands of years is a fallacy.[http://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf]

When the Europeans colonized Austrailia, the Indigenous people and culture declined drastically. They currently have high levels of smoking as Europeans introduced tobacco to their culture. [http://www.nsma.org.au/facts/aborignl.htm]

Australian Aborigine

2009-05-01T02:24:14Z

Inverness: Created page with 'The Aboriginies, or more correctly termed "Indigenous Australians" lived in Austrailia as far as 50 000 years ago. New genetic evidence suggests that multiple waves of people mig...'