Changes
Rephrasing to improve clarity
[[Image:BoyleSelfFlowingFlask.png|right|thumb|[[Robert Boyle]]'s self-flowing flask appears to fill itself through siphon action. This is not possible in reality because a siphon requires its "output" to be lower than the "input".]]
A '''perpetual motion machine''' is a [[hypothetical]] isolated system capable of having internal motion indefinitely. Many attempts to build such a system have failed for a simple reason: disorder is always increasing (because of the fundamental uncertainty described by [[quantum mechanicsentropy]](disorder)is always increasing, and a perpetual motion machine would defy that law.
A perpetual motion machine would try to use its initial energy to remain in motion perpetually. Because [[entropy ]] is always increasing, even in closed (and isolated) systems, indefinite motion is impossible because an increase in the disorder of the system will inevitably disrupt the motion and require additional energy to "fix" it. The [[Second Law of Thermodynamics]] predicts that a perpetual motion machine in this sense is impossible, and none has ever been created.
An even less plausible type of perpetual motion machine would continue to perform work without new any input of energy, thereby serving as an unlimited energy source. This is prohibited by the [[First Law of Thermodynamics]], which states that energy must be conserved.
Since both types of perpetual motion machine are flawed in both theory and in practice, they are clearly [[pseudoscience]]. Despite this, websites have professed to offer "free energy" devices for sale.<ref>http://www.free-energy-info.co.uk/</ref><ref>http://www.fuellesspower.com/</ref><ref>http://www.magniwork.com/</ref>
