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Are atoms 'perpetual machines'?

  1. Jul 7, 2008 #1
    Are atoms 'perpetual machines'? To me it seems they are??? Does friction affect electrons at all?

    For example, A rock's atom's electrons have been orbiting the nucleus for the past, say 4 billion years without energy being supplied to the atom... Thanks for your input.
     
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  3. Jul 7, 2008 #2

    Defennder

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    It's not accurate to think of microscopic objects in terms of macroscopic features. At the level of the electrons friction doesn't exist. This makes as much sense as asking what colour is an electron or what smells and feels like. It's not really accurate to talk about electrons oribiting the nucleus, but depending on the level of the answer you're seeking it suffices as a rudimentary picture. And as for the orbiting, hasen't the Earth also orbited the sun since its formation 4 billion years ago? What energy has been supplied to the Earth to make it orbit? As have all the other planents and comets?
     
  4. Jul 7, 2008 #3

    russ_watters

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    The term "perpetual motion" isn't quite meant literally, Deseree, as Newton's first law would imply (objects in motion remain in motion forever unless acted upon by an outside force). There are several different kinds of perpetual motion machines: http://en.wikipedia.org/wiki/Perpetual_motion_machine#Classification
     
  5. Jul 7, 2008 #4
    the electron cloud doesnt orbit the nucleus. except for vibration due to heat, its stationary.
     
  6. Jul 8, 2008 #5

    HallsofIvy

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    Can you cite any evidence for such a statement?
     
  7. Jul 8, 2008 #6
    as opposed to what? what is your theory?
     
  8. Jul 8, 2008 #7

    Defennder

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    I don't think it's particularly meaningful to describe an electron cloud as "stationary", as though the concepts of motion and stillness applied to it.
     
  9. Jul 8, 2008 #8

    brewnog

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    The purpose of a "machine" (and thus a "perpetual machine", were such a thing to exist) is to produce work. Clearly atoms don't do this.
     
  10. Jul 8, 2008 #9
    As I understand it, electrons around a nucleus are more like a probability cloud. If I'm remembering correctly, at that level it starts falling into quantum mechanics. They don't really orbit on specific planes like planets around a sun, but rather are more likely found in one position rather than another around the nucleus. I'm pretty sure it has to do with the Heisenburg uncertainty.
     
  11. Jul 8, 2008 #10
    Well I understand the Newton's laws: There is no friction in the way of earth so it keeps on moving...but the question is mainly about electrons. And to this point I have seen good posts...
     
  12. Jul 8, 2008 #11

    ZapperZ

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    You might want to read the FAQ in the General Physics forum and see if your view of how electrons behave in an atom requires a major modification. After you understand that, see if you think you still want to ask this question.

    Zz.
     
  13. Jul 8, 2008 #12
    I am not going to "modify" it and don't have any views on it, just wanted to have a good answer/explanation if someday some curious lay person(like me)asked me about it. Is it clear now?:)
     
  14. Jul 8, 2008 #13

    ZapperZ

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    No it isn't. Have you read the FAQ? Because if you have, then you would have seen that your starting point isn't valid. We have no "electrons orbiting a nucleus" the way you seem to picture it. Thus, your question is based on something that isn't valid in the first place. So you can already see how futile it is to come up with an answer.

    Zz.
     
  15. Jul 13, 2008 #14

    DaveC426913

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    What people are trying to say is simply that electrons do not "orbit" the nucleus. Today, we don't ask so much what they are doing when we are not measuring them becasue we can't predict where they will be; we simply ask where we might find them at any given time that we go to measure them. It is a measument of probability. (I believe this is what Feynman meant when he famously said "shut up and calculate!" It means don't ask how or why, just do the math and you'll get the answer.)

    This probability, when we map it all out, forms a "cloud" of a particular shape around the nucleus. Different electron states result in different cloud shapes. Look up 'electron orbitals' for more info.

    Noe of this directly helps answer your question, but it may help you phrase your questions without getting caught up in details.


    The electron isn't stationary, but the shape of the probability cloud is (inasmuch as a probability cloud can be).
     
  16. Jul 13, 2008 #15

    jtbell

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    The posts about proton decay have been moved to a new thread, in order to keep this thread focused on its original topic.
     
  17. Jul 13, 2008 #16

    Andy Resnick

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    Atoms are not machines; atoms do not move. Bound electrons are stationary objects, using the correct mathematical definition of a stationary state. Thus, one cannot use them to extract work. Neither do dissipative processes occur.
     
  18. Jul 14, 2008 #17
    To be accurate, shouldn't we stick to saying the wave function of a bound electron is a stationary state? I mean, in principle you can measure a single electron at a certain location A, allow its wave function to spread out again according to the Schroedinger equation, and then measure it at another location B, which implies at least a lack of "stationary-ness" on the electron's part (although I should be careful with this, since it's unclear how the electron got from A to B in the first place). Is this incorrect?
     
  19. Jul 14, 2008 #18
    Everything here is a question of language. If you think about friction for an electron like you do it for a plane in the air, then you have a wrong representation. First of all because there is no air between the nucleus and the surrounding electrons. If you define the concept of friction as being any phenomenon characterizing a reaction with the surrounding environment, and if you consider the surrounding environment as being a set of EM fields, then yes one could imagine a reaction between an electron and these fields. But, stricto sensu, it is not the usual context for that word: “friction”; and so you will hurt the community.
    Now, if one considers the asked question at a semi-philosophical level, then yes one can effectively wonder about the stability of some natural structures, for example atoms, … as long as nothing is breaking them!
    The question concerning electrons having apparently permanent motion inside a material is another complicated item and is correlated to the supra conduction. I think it was not your initial question.
     
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