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LoCoE and perpetuum mobile

  1. Jan 6, 2006 #1
    According to the laws of Conservation of Energy, there can be no such thing as a perpetuum mobile of any kind.

    The purpose of this topic is not no disprove them in any kind.

    But then i began to think:

    A battety re-charger is powered by a battery which in turn runs the battery recharger.

    This theory alone will of course not work, but as in all sciences we have the "what if" variable.

    Lets say we make that circut frictionless and but it into complete darkness in absolute vacuum at 0 K. Would that run forever?

    (Of course there is not absolute vacuum anywhere in the universe)

    What part of this line of thought is inaccurate from my part?

    And how about Big Bang, was energy created there? Energy must surley have come from something in the beginning?
  2. jcsd
  3. Jan 6, 2006 #2


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    Air, or the lack thereof, has essentially no effect upon electrical circuits. What you want is superconductivity, for which temperatures near to 0 K are required. The circuit that you propose, if superconducting, might just keep a current flowing around in a loop, but there's no way that you could extract any work from it.
  4. Jan 6, 2006 #3


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    Not only that, but there's also ANOTHER problem. While your wires might be superconducting, your connectors and internal parts of the batteries are NOT! Ohmic losses are still inherent in such a thing.

    I'm not sure why we're bothering with such a system. An atom is technically a "perpetual" something. However, to get any effect (work, energy, etc) out of it, it must INTERACT with something, and this is where energy transfer occurs and the "perpetualness" no longer applies. The same with a superconducting loop. By itself, it is useless and it isn't a "machine". When you interact with it to get energy out of it, that is when it will start losing energy and diminish its perpetualness.

  5. Jan 6, 2006 #4
    Ah, i see!

    Thanks for the tourough replies!
  6. Jan 6, 2006 #5


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    My thanks to Zapper as well, for pointing out something that I hadn't thought of. You can't have a superconducting battery. Any chemical activity would cause resistance. I'm not so sure about the connections though; if there could be a perfectly smooth interface between two components (as in Johanson blocks--and I probably spelled that wrong), then I'd expect it to act as a single continuous conductor. More input, please, Mr. Z. :smile:
  7. Jan 7, 2006 #6


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    I'm not familiar with Johanson blocks. However, quantum mechanically, when a superconductor comes in contact with a normal-state metal, you get a discontinuity in the boundary conditions at the junction. You can get a number of effects, including the proximity effects here. The supercurrent wavefunction can undergo a number of things, including something called Andreev scattering. The charge careers can get "reflected" off the boundary. So even with a perfect connection, you still lose.

  8. Jan 7, 2006 #7
    You can never win, you can only break even

    You only break even at absolute zero

    You can never reach absolute zero

  9. Jan 7, 2006 #8


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    Hi Marlon. You wouldn't believe how many times I've wanted to post that, and always managed to restrain myself. :rofl:
    ZZ, the blocks that I mentioned are slabs of steel that are so finely machined that they stick to each other. As far as I know, their only practical use is to demonstrate Van der Waals forces. For the sake of clarification, I had assumed that every component in the system was superconducting, with no 'normal state matter' present. It seemed to me that in such a case, the current wouldn't 'realize' that there was a junction present.
  10. Jan 7, 2006 #9
    Well, we are very close to reaching absolute 0 already.

    The superconductive electromagnets in the LHC (Large Hadron Collider) or the previous Large Electron Positron collider (LEP) at CERN will have/had them cooled to (correct me if i am wrong) not more than a very few degrees over 0 K.
  11. Jan 7, 2006 #10
    But close is not equal to at. When we're talking about reaching 0K there's a huge difference.
  12. Jan 7, 2006 #11
    Not really. It all depends on what you want to do. The heat energy is not that much bigger at 1K that it is at 0K in terms of J
  13. Jan 7, 2006 #12


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    Well, if what you want to do is reach absolute 0, then almost reaching absolute 0 is still a failure.
  14. Jan 7, 2006 #13


    This answer is indeed the easy (yet correct) way out... It actually covers over 90% of the answers one has to give to thermodynamics questions and especially these perpetuum mobile type questions.

  15. Jan 7, 2006 #14
    But how about Big Bang? Energy/mass must have been created there?
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