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The One Electron Universe

  1. Dec 16, 2015 #1
    I have heard that Feynman and Wheeler briefly discussed the idea of the 'one electron universe'. According to Wikipedia it came up as follows:

    It wasn't really a serious idea, more a 'thought experiment'. But what interests me is the fact that electrons are literally indistinguishable. Not only do they all have exactly the same properties, but 'it's essentially impossible to tell them apart at all. This is because determining specific electrons by their position would require measuring their trajectories with exact precision, and the laws of quantum mechanics forbid this.' 1

    So this leads me to ask the question: do electrons exist? The obvious answer is, of course they do, you can capture their signal in all kinds of experiments. But the criterion for something that 'exists' is generally that it has an identity - it is 'this' as distinct from 'that'. The word 'exist' means to stand (ist) apart (ex).

    So the 'one-electron universe' is not really that whimsical an idea. Something corresponding to 'electrons' can certainly be described, and it fulfils certain functions and turns up in predictable ways. But whether it exists can still be legitimately questioned. (I know that this is a tricky philosophical issue, but I would be interested to hear others' views on it.)
     
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  3. Dec 16, 2015 #2

    Ryan_m_b

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    Electrons do have an identity that separates them, the electron in one atom can be associated with that atom versus one in another.
     
  4. Dec 16, 2015 #3
    Macroscopically, negative charges repel other negative charges, and we have deduced this is a mass version of the same property in individual negative charges. You can't physically put two electrons in the same space and appear to have one electron the way you can with, say, two congruent triangles. So, it is electrons, themselves, that tell us they are distinct entities from each other.

    But, the thing electrons are mostly distinct from are protons and neutrons. To propose that electrons might not exist because we can't distinguish one electron from another (in the sense they all have the same properties), is just kind of whacky, and would require we also propose protons and neutrons don't exist for the same reason. Then you'd have to propose nothing exists.
     
  5. Dec 16, 2015 #4

    PeroK

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    Electrons are not special by being indistinguishable. See, for example:

    https://en.wikipedia.org/wiki/Identical_particles

    You have not really grasped what it means for electrons to be indistinguishable. Although you cannot label individual electrons (or other elementary particles) in any way, it's also the case that no two electrons can be in the same state. In an atom, for example, there can only be one electron in each possible state. If there are two in the same "energy" state, then one will be spin-up and one spin-down.

    Finally, the meaning of the word "exist" has no relevance to the physics of an atom, for example. You could conclude that electrons do not exist and the standard model of the atom with its electrons would be no better or worse as a result.
     
  6. Dec 16, 2015 #5
    Electrons do have a position in space and time (sort of) so they are not indistinguishable from each other, what Feynman was talking about was the fact that they seem to have no internal structures so that if you pulled one out of a box with some electrons in it, examined it, then put it back and pulled another one out, you wouldn't be able to determine if it was the same one or not.

    The one electron universe was quickly determined to be impossible by Feynman himself, who according to him, he immediately asked then why there were more electrons than positrons.
     
  7. Dec 16, 2015 #6

    Evo

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    Since we don't do philosophy anymore, thread closed.
     
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