Wednesday, September 21, 2011

Physics News: Electron Shape

Physics News will be a new feature of this informal journal of binary mechanics (BM) [1] highlighting research supporting predictions of the theory. This installment considers the BM prediction that the electric dipole moment (EDM) of the electron is exactly zero. A recent report by Hudson et. al. in Nature on "Improved measurement of the shape of the electron" [2] states: "This result, consistent with zero, indicates that the electron is spherical at this improved level of precision." In an email exchange with one of the six co-authors of this paper, I wrote:
In binary mechanics (e.g., "Physical interpretation of binary mechanical space" ... [3]), which postulates an internal structure for the electron, the constituent bits (called mites) "spin" in a plane orthogonal to the spin axis, where each of three possible equally-spaced mite bit loci is equidistant from the particle's center of mass and symmetrically located around the spin axis.

sciencedaily.com reporting on your Nature letter states (AFAIK, their words, not yours): "If the electrons were not perfectly round then, like an unbalanced spinning-top, their motion would exhibit a distinctive wobble, distorting the overall shape of the molecule. The researchers saw no sign of such a wobble."

Which leads to several questions:

1. What logic leads to the conclusion of spherical shape as opposed to, say, a perfectly balanced "spinning-top", which is basically what I described above re the binary mechanical model of the electron's internal structure? Or rephrasing, is the sphere the only shape that is compatible with your results? Or more specifically, is a perfectly balanced spinning top consistent with your results (per the sciencedaily description)? If so, then I might tend to suspect that your results are indeed consistent with binary mechanics.

2. I gather that your team does not consider the electron to be a point-like (0-dimensional) object (and neither does binary mechanics). If this is true, what is the radius of the sphere (and/or if allowed, the perfect spinning top)?
The reply was:
We look for a torque d (s x E), where s is a unit vector along the electron spin, E is the electric field vector seen by the electron (proportional to the applied electric field) and d is the dipole moment. The dipole moment corresponds to a displacement of charge along the spin axis. We measure the precession angle of the spin due to this torque. This says nothing about the radius of the electron. In fact, the radius is a matter of definition - it depends what measurement you consider. A picture I like is the point electron surrounded by the fuzz ball of virtual particles, which interact with the electron and give it the structure that we observe (charge, mass, magnetic moment and electric dipole moment).

Our experiment is a way to search for interactions beyond the standard model because the particles in the standard model do not induce a significant EDM, whereas additional particle generally do. I am not sure if this orthodox view of quantum field theory has much connection with your picture. There is certainly no experimental evidence for any internal structure of the electron beyond what it gets from its coupling to the vacuum...
Discussion
1. Concerning the electron electric dipole moment, the gracious and helpful reply cited above does not exclude electron shapes other than a sphere, such as the perfect "spinning top" concept mentioned in the sciencedaily commentary and apparently consistent with the BM prediction. The published Nature paper seems to commit to the sphere shape. Hence, it might be a source of some minor embarrassment that other shapes consistent with the experimental results were not considered in the paper [2], which states [emphasis mine]:
Here we use cold polar molecules to measure the electron EDM at the highest level of precision reported so far, providing a constraint on any possible new interactions. We obtain de = (2.4 ± 5.7stat ± 1.5syst)×10-28 e cm, where e is the charge on the electron, which sets a new upper limit of |de| < 10.5×10-28 e cm with 90 per cent confidence. This result, consistent with zero, indicates that the electron is spherical at this improved level of precision.
although the text could have said, "the electron is spherical or a perfect spinning top shape". In other words, it appears that the data does not exclusively support a spherical electron shape, although one major .gov science site had an artist showing the electron as a red ball.

2. It is natural for investigators to present their results in the context of "the orthodox view". On the other hand, applause is due for the effort to explore "beyond the Standard Model". Indeed, research reports often contain a mix of the orthodox and a look beyond it.

3. Regarding the second question on electron diameter, the reply correctly indicates that the EDM information does not address that issue. This question was posed as a probe since much "orthodox" thinking appears to attempt to describe the electron either as a point (0-dimensional) charge or as a sphere, contradictory concepts each invoked whenever convenient, without any clear or consistent rationale. Specifically, if the electron is a sphere, does not logic dictate that there must be some "internal structure"? Or are we to suppose that the electron is the only known sphere without internal structure?

4. The electron's "coupling with the vacuum" is completely and exactly described in BM, which represents a striking contrast to the seemingly ad hoc and vague conceptualizations prevalent among many physicists.

5. In conclusion, the Hudson et. al. report may be interpreted as experimental support for the BM prediction that the electron has a zero electric dipole moment.

References
[1] Keene, J. J. "Binary mechanics" J. Bin. Mech. July, 2010.
[2] Hudson, J.J., D.M. Kara, I. J. Smallman, B. E. Sauer, M. R. Tarbutt and E. A. Hinds "Improved measurement of the shape of the electron" Nature, 473, 493–496. DOI:10.1038/nature10104 May, 2011.
[3] Keene, J. J. "Physical interpretation of binary mechanical space" J. Bin. Mech. February, 2011.
© 2011 James J Keene