Is perpetual motion impossible?

Discussion in 'Chemistry' started by Chatha, Apr 27, 2007.

  1. John Connellan Valued Senior Member

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    Theoretically, one could envisage a universe with only 2 particles orbiting around each other....perpetually
     
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  3. EmptyForceOfChi Banned Banned

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    in space it is totaly possible, but on earth i dont think so because gravity will always have a downward pull, in-time stopping the movement.

    peace.
     
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  5. James R Just this guy, you know? Staff Member

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    Yes, but as I explained earlier, that is not the kind of perpetual motion that is prohibited by the second law of thermodynamics. It prohibits, among other things, perpetual motion machines.
     
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  7. Star6966 Registered Senior Member

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    Theoretically, one could envisage a universe with only 2 particles orbiting around each other....perpetually

    True but one could also envision something similar to David Hillard's Grand Hotel but that doesn't mean that it is possible
     
  8. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    "orbiting around each other"

    You clearly assume that they gravitationally attract each other, but are forgetting that they lose enegy and spiral together due to the gravitational wave radiation energy losses, assuming current phsics of this is correct.
     
  9. James R Just this guy, you know? Staff Member

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    Yes. In fact, there are many similar things that could be called "perpetual motion" - for example an electron in a hydrogen atom will theoretically "orbit" the nucleus forever.

    But when people talk about perpetual motion, and perpetual motion machines in particular, they mean real, macroscopic devices that never run down, or devices for which the energy output is more than the energy input (so-called "over-unity devices"). This is the kind of perpetual motion that defies the laws of physics (thermodynamics).
     
  10. iceaura Valued Senior Member

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