Electrons are near-perfect spheres

Electrons differ from being perfectly round by 0.000000000000000000000000001cm, writes Wired UK's Duncan Geere: "To put that in context; if an electron was the size of the solar system, it would be out from being perfectly round by less than the width of a human hair." Wherever you go, sphere you are!


  1. ok now i’m confused. i thought electrons were point masses like quarks, occupying no volume whatsoever.

  2. AFIK, the solar system is elliptical, not round. So we’re talking apples and oranges here. :)

  3. To be precise, that is the limit of their measurement accuracy which provides an upper-bound on the non-spherical shape of the electron. Electrons may in fact be more spherical than that – or a perfect sphere. Found the wording misleading that the electron was found to be not spherical, which isn’t the case.

  4. Rob, you’ve misread the article: it doesn’t say electrons aren’t spherical, it says that if they aren’t, it’s by less than 0.000000000000000000000000001 cm because that’s the limit of their asphericality measuring rig.

  5. Gee, an electron doesn’t even have a position that can be fixed with arbitrary certainty. Exactly in what sense does it have a shape? Doesn’t it’s “shape” depend on what orbital it is in?

  6. Between this repost and the original WIRED article, there are enough bad analogies to thoroughly scramble anyone’s brain. For starters, an electron is a fundamental building block. It is not made up of other stuff, so saying that it even has a shape is a misnomer. And the article states that even using this bad analogy, they don’t detect any a-symmetry in the shape at very high levels of precision. So it may be ‘perfectly round,’ whatever that means, we just don’t know.

    I think we can understand what a dipole moment is if it’s explained the right way. Can we please bring Maggie into this discussion and start from scratch?

    1. Correction: as far as we know the electron is not made up of anything else. However, as far as we know the electron also has zero electric dipole moment. The whole point of these kinds of experiments is to test some of the fundamental assumptions of our current theories.

      Claiming that “saying that it even has a shape is a misnomer” is missing the mark. One should say “so far we have no evidence that it even has a shape.” The standard model does not predict it having a shape, but we already know the standard model is incomplete.

      The electric dipole moment is a straightforward measure of a distribution of charge. Mathematically, it’s just the volume integral of charge density times the position vector. For a perfect sphere of uniform charge density, you can see that the vector pointing to any spot in the sphere will be exactly canceled by a vector in the opposite direction (by definition the center of integration is the center of amss). A random little bump in the surface (or non-uniform charge distribution) will destroy that symmetry.

      There could be symmetric distortions of the sphere that would not result in a dipole moment, but really, the original research was about dipole moments, not sphericalness.

  7. Science can’t ever say ‘the electron is round’ but it can measure roundness to an incredible accuracy. This puts limits on theories that predict electrons to have bumps at extreme scales, so it’s pretty important in weeding out theories

    What is being measured here is a consequence of a property the electron has called spin. It is analogous to a spinning top, but does the electron have a definable left side and a right to ‘spin’ around? If they do and there is a bulge from the spinning a magnetic effect arises that can be measured.

    They have sent electrons spinning through a magnet, and tried to measure the amount by which the electrons wobble. A bit like a spinning top that eventually tips over. They basically couldn’t find any tipping within the accuracy of their equipment so the electron has Inception-like stillness!

  8. No, this posting is incorrect; the experiment does not show that electrons are “off” in any amount from being spherical, and the result is consistent with electrons being mathematically perfect spheres (if that has any meaning; they evidently have no internal structure and “perfectly spherical” would just mean that they are completely symmetric).

  9. No wonder whenever you put one down, it always rolls to having the same side up.

  10. what, exactly, is meant to be near-perfectly spherical? electrons per se are of course not eligible for this or any other shape. some kinda spherical symmetry in their electric field i guess?

  11. The slight chance of it being off is what you find interesting? What about the fact that they weren’t allowed to look at the results while this was running for fear of prejudicing the results…. (Cue the Weird Science Theme)

  12. No, that’s absolutely not what the article says. The article says that as far as they can tell, electrons /are/ perfectly spherical, and lists the precision of their estimate. Please update your post (and read more carefully next time…)

  13. Am I the only one who is impressed that they can measure that accurately at that scale (or any scale, really)?

    I mean, that is some serious mindfuck accuracy right there.

    1. Am I the only one who is impressed that they can measure that accurately at that scale (or any scale, really)?

      I mean, that is some serious mindfuck accuracy right there.

      No. But what interests me about the analogy provided is that it illustrates just how hard it is to wrap your head around such orders of magnitude.

  14. Cripes, the echo is getting so distorted it makes no sense anymore. This is a Boing Boing post of a Wired piece about a Science Daily article that actually refers to the Nature paper this is based on.

    Theory actually predicts that the electron’s electric dipole moment is aspherical, but at a level below current detection limits. This paper has put tighter bounds on those detection limits, and still hasn’t found deviation from a sphere. It still doesn’t come close to being able to test the predictions of the standard model.

  15. Another summary of the work for those without Nature access. With pictures of goggles and lasers and an actual experiment instead of a Van der Graaf generator or a billiard ball.

  16. This allowed the team to place an upper limit on the EDM of 10.5 × 10–28 e cm

    Thanks, I don’t like to count zeros. That’s why 10.5 x 10^28 was invented.

  17. All these debates about whether the election is “a perfect sphere”, or like this or like that, in layman terms, are pretty useless. The electron’s fundamental principles are described in complex mathematics, and cannot be “explained away” with some simplified model or philosophical principle that everyone understands while still maintaining a semblance of truth.

    If you want to understand this argument in its original form (and have access to Nature), here’s the paper: http://www.nature.com/nature/journal/v473/n7348/full/nature10104.html

    Of course, a solid background in physics and mathematics is necessary for this – but it is unavoidable! To understand music, you have to be able to hear it first.

    This is, at least in part, what Feynman argued in one of his lectures (http://research.microsoft.com/apps/tools/tuva/index.html) – that qualitative interpretation of the laws of nature (statements like “the electron is spherical”, or “it is sometimes a particle and sometimes a wave”) are rarely true or useful.

    Here are some excerpts of his speach

    “The strange things about physics is that for the fundamental laws, we still need mathematics. [for example] there is no theory of gravitation today other than the mathematical form. […] The more we investigate, and the more laws we find, and the deeper we penetrate nature, [we find] this disease – that every one of our laws is a purely mathematical statement in rather complex and abstruse mathematics.

    All right then, there is no explanation of the law. At least tell me what the law is – tell me in words, instead of in [mathematical] symbols. Mathematics is just a language, and I want to be able to translate the language.

    Various different people get different reputations for their skill at explaining to the layman in layman’s language these difficult and abstruse subjects. The layman then searches book after book with the hope of that he will avoid the complexity which ultimately sets in. [… but] I don’t think it’s possible, because mathematics is not just a language […] it is a tool for reasoning.

    [Contrary to abstract mathematics] the physical laws are so delicately constructed, that the statements of them have qualitatively different characters, that it’s very interesting. […] When you know what is it you are talking about – that these things are forces, and these are masses, and this is inertia, and this is so on – then you can use an awful lot of commonsense seat-of-the-pants feeling about the world: you’ve seen various things, you know more or less how the phenomenon is going to behave.

    The next point is the question of whether we should guess, when we try to get a new law, whether we should use a seat-of-the-pants feeling, and philosophical principle. Very often models help, and most physics teachers try to teach how to use these models and get a good “physical feel” for how things are going to work out. But the greatest discoveries, it turns out, always abstract out from the model, [the model] never did any good.

    If you want to discuss nature, to learn about nature, and to appreciate nature, it’s necessary to find out the language that she speaks in. She offers her information in one form. [He means mathematics]

    […] People like me, who’s trying to describe it to you (but is not getting across because it’s impossible), we’re talking to deaf ears.”

    1. With all due respect to Feynmann. . . doesn;t all that imply that the word “electron” is meaningless?

      After all, it’s an english word, not a mathematical symbol.

      The only reasonable course of action is to maintain a zen-like silence. To even disagree with a non-scientist is to depart from the purity of science.


      1. I’m with you. I say the near-perfection of the sphere that is the electron is its polarization.

        Neutrons…. now those dudes are perfect spheres, balanced, difficult to excite, and you can totally know where they stand and where they’re going.

  18. This article is not even wrong in so many ways that it’s created some kind of zen black hole of not-even-wrongness.

    An electron doesn’t have a shape, it has a probability distribution. The attribute called “spin” isn’t precisely the same as angular momentum. The attributes being measured here are abstractions that we can only understand through analogies.

  19. Electrons are just the phi(x,t) in (-i * gamma^mu * partial_mu – M)*phi(x,t) = 0. That’s all!

  20. It appears the original authors chose “roundness” as the way they were going to pronounce “electric dipole moment” in public. On the one hand I respect the fact that they anticipated the difficulty in presenting the technical term. On the other hand, now they’re stuck with answering questions like “How can you measure the roundness, when you don’t know the diameter?”; questions that can’t be translated back to the original technical language. Analogy fail.

    — James Ph. Kotsybar

    An electron, so perfectly round
    it could spin without wobble or sound,
    was measured carefully
    at fixed velocity,
    but its position couldn’t be found.

Comments are closed.