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Talk:Perpetual motion machine (view source)
Revision as of 15:03, January 3, 2007
, 15:03, January 3, 2007no edit summary
More thought and research would be worthwhile here. I think we're all convinced that the motion would eventually stop. But why? What force stops it? --[[User:Aschlafly|Aschlafly]] 22:36, 2 January 2007 (EST)
More thought and research would be worthwhile here. I think we're all convinced that the motion would eventually stop. But why? What force stops it? --[[User:Aschlafly|Aschlafly]] 22:36, 2 January 2007 (EST)
:It's beyond my own knowledge. I suspect such questions are like the irresistable force and the immovable object, though. Provisionally, let's call your gadget an "endless coaster."
:Point #1: At least according to Newtonian physics as I understand it, if you truly had a closed system, it would not stop. But if you truly had a closed system, there would be no way to ''see'' that it was still moving.
:In order to observe it, there would have to be some energy exchange between the "perpetual motion" and the observer. I have an idea that since the observer is gaining information, the observed must be gaining entropy, but that's just handwaving and I don't know how to prove it.
:What I don't know whether there are any theoretical reasons that would make it ''impossible'' to have a truly closed system.
:Here's another angle. If we're considering, say, a ball bearing magnetically suspended in a vacuum by a superconducing magnet or something like that, if if there is a ''small'' amount of friction the result, according to classical physics, would be to make the ball bearing spin slower ''on an exponential decay curve.'' It would have a half-life, like radioactive decay. Perhaps it loses half of its spin every day. Well, according to classical physics, it would spin slower and slower but ''would never actually stop.'' Asymptotically approaches zero, never eaches it. Most likely (out of my depth again) ''quantum'' physics would say that at some point the spin becomes quantized, meaning that after some period of time it can't slow down any more. The spin must be either one quantum or none... and then you get all that crazy wave-function collapse stuff. You have a superimposed state in which the spin is one with some probability and zero with some probability, and the probability decreases over time.
:But really, once you start talking about whether something can literally go on forever, you're outside the bounds of science. I can't keep track of the number of times the "scientific" narrative of cosmology has changed during my own lifetime, and it shows no signs of settling down. Is the universe closed? Open? Continuously expanding? Oscillating? Obviously, ''if'' physics predicts a ''finite'' lifetime for the universe, then a "perpetual" motion, meaning one that would last longer than the universe, is impossible. [[User:Dpbsmith|Dpbsmith]] 10:03, 3 January 2007 (EST)