Difference between revisions of "Perpetual motion machine"
(Reworded the last paragraph to say basically the same thing without implying the truthfulness of the 2nd law argument) |
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| − | A perpetual motion machine is a | + | A perpetual motion machine is a hypothetical isolated system capable of having internal motion indefinitely. Many attempts to build such a system have failed. |
One type of a perpetual motion machine would continue to perform work without new energy, thereby serving as an unlimited energy source. This is prohibited by the [[First Law of Thermodynamics]]. | One type of a perpetual motion machine would continue to perform work without new energy, thereby serving as an unlimited energy source. This is prohibited by the [[First Law of Thermodynamics]]. | ||
Revision as of 17:24, January 3, 2007
A perpetual motion machine is a hypothetical isolated system capable of having internal motion indefinitely. Many attempts to build such a system have failed.
One type of a perpetual motion machine would continue to perform work without new energy, thereby serving as an unlimited energy source. This is prohibited by the First Law of Thermodynamics.
Another type of perpetual motion machine simply uses its initial energy to remain in motion perpetually. It is more difficult to prove that this is impossible, but it might violate the Second Law of Thermodynamics. If entropy is always increasing, even in closed (and isolated) systems, then indefinite motion is impossible because an increase in the disorder of the system will inevitably disrupt the motion.
This argument is the only evidence against this type of machine.