the tree Posted August 22, 2005 Share Posted August 22, 2005 Here's my idea for a perpetual motion machine, I challenge anyone to find a weakness in it. A heavy object such as a bolder is placed on a completely flat surface, the object is then moving a velocity of zero. Without any major disturbance, it's velocity remains the same, perpetual if you will. The object never slows down, and no energy is lost. Edit: it being tottally useless doesn't count against it being a perpetual motion machine. Link to comment Share on other sites More sharing options...
MetaFrizzics Posted August 22, 2005 Share Posted August 22, 2005 velocity of zero relative to what? If it is in an inertial frame, great. How do you guarantee you and the boulder are in an inertial frame? Link to comment Share on other sites More sharing options...
the tree Posted August 22, 2005 Author Share Posted August 22, 2005 The boulders velocity is mesured relative to the surface that it is placed on. Link to comment Share on other sites More sharing options...
Pangloss Posted August 22, 2005 Share Posted August 22, 2005 An amusing point, but of course it violates the most basic requirement of perpetual motion, which is that it must be changing position with respect to time. If you are referring to the fact that it is moving, along with its surface, you know that that's not perpetual, right? The Earth's rotational motion is not perpetual at all. Link to comment Share on other sites More sharing options...
the tree Posted August 22, 2005 Author Share Posted August 22, 2005 An amusing point, but of course it violates the most basic requirement of perpetual motion, which is that it must be changing position with respect to time.Bugger. Oh well.If you are referring to the fact that it is moving' date=' along with its surface, you know that that's not perpetual, right? The Earth's rotational motion is not perpetual at all.[/quote']I wasn't refering to that. And yes I am aware of that. Link to comment Share on other sites More sharing options...
CPL.Luke Posted August 23, 2005 Share Posted August 23, 2005 hey what about a beam of light that orbits the sun/other body. that would move forever Link to comment Share on other sites More sharing options...
Pangloss Posted August 23, 2005 Share Posted August 23, 2005 hey what about a beam of light that orbits the sun/other body. that would move forever But it wouldn't generate energy, which of course is the whole point. Perhaps (I don't know enough to know if that's possible or not) it might make a perfect energy storage device, but as soon as you extracted its energy it would be gone, and then you'd have to replace it somehow. The article I linked earlier in this thread mentions Richard Feynman's thought experiment on Brownian motion, called a Brownian Ratchet which readers of this thread might find interesting. Link to comment Share on other sites More sharing options...
Severian Posted August 23, 2005 Share Posted August 23, 2005 hey what about a beam of light that orbits the sun/other body. that would move forever It would still dissipate. It would split into virtual electron-positron pairs which would radiate, losing energy. Link to comment Share on other sites More sharing options...
CPL.Luke Posted August 23, 2005 Share Posted August 23, 2005 not if it was of energy lower than 1Mev though right? Link to comment Share on other sites More sharing options...
Severian Posted August 23, 2005 Share Posted August 23, 2005 If they are virtual, the energy doesn't matter. Link to comment Share on other sites More sharing options...
Pangloss Posted August 23, 2005 Share Posted August 23, 2005 It would still dissipate. It would split into virtual electron-positron pairs which would radiate, losing energy. That's interesting, I didn't know that. Why isn't that a disproof of Olber's Paradox? (Which, so far as I've read, is disproven by other means, such as the argument that the universe is finite, or that it is unevenly distributed.) Is it just that the light breaks down so slowly that it would still fill the sky with light (if not for those other factors) before a significant amount of it broke down? Link to comment Share on other sites More sharing options...
Severian Posted August 23, 2005 Share Posted August 23, 2005 Is it just that the light breaks down so slowly that it would still fill the sky with light (if not for those other factors) before a significant amount of it broke down? Yes, the energy isn't lost - it is just redistributed. Since it would be happenning the same everywhere you look you would still get the infinitely bright sky (I think). Also, not all photons will do this. You need to emit two photons at once to conserve momentum, which is quite unlikely, so there is a very good chance that light from a distant star came directly to your eye (otherwise spectroscopy wouldn't work). I was only pointing out that it would not live infinitely long. Link to comment Share on other sites More sharing options...
Pangloss Posted August 23, 2005 Share Posted August 23, 2005 Fascinating, thanks! Link to comment Share on other sites More sharing options...
Sayonara Posted August 26, 2005 Share Posted August 26, 2005 Here's my idea for a perpetual motion machine, I challenge anyone[/i'] to find a weakness in it. For future reference, when challenging people to find a weakness in your theory, make it "everyone" instead of "anyone". It's more difficult for them to get organised that way. Link to comment Share on other sites More sharing options...
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