Hi Harry and Robin, It's an experimental measurement all right, to one ppT all right. They sequester a single electron for months on a large (0.1µm) circular orbit and count photons as I understand, do have a look at the short CERN paper (only the abstract in the beginning is in French, the rest is in English) :
http://cerncourier.com/cws/article/cern/29724 I have OCR'd the "Dear Gerald" letter therein for you: <<Dear Gerald...As one of the inventors [of QED], I remember that we thought of QED in 1949 as a temporary and jerry-built structure, with mathematical inconsistencies and renormalized infinities swept under the rug. We did not expect it to last more than 10 years before some more solidly built theory would replace it...Now, 57 years have gone by and that ramshackle structure still stands... It is amazing that you can measure her dance to one part per trillion and find her still following our beat. With congratulations and good wishes for more such beautiful experiments, yours ever, Freeman Dyson. (Dyson 2006).>> I find this impressive, especially considering that the (computer assisted of course) theoretical computation, to the same accuracy, involves accounting for such wonderful possibilities as the photon going from the magnet to the electron turning into an electron-positron pair and the latter recombining again into a photon on the way, and this at any possible place in space-time, as explained in Feynman's enlightening little (160 pages) 1985 QED book, see the following excerpts from p.115 and following: <<Finally, I would like to return to that number 1.00115965221, the number that I told you about in the first lecture that has been measured and calculated so carefully. The number represents the response of an electron to an external magnetic field-something called the "magnetic moment.">> <<Laboratory experiments became so accurate that further alternatives, involving four extra couplings (over all possible intermediate points in space-time), had to be calculated, some of which are shown here. The alternative on the right involves a photon disintegrating into a positron-electron pair (as described in Fig. 64), which annihilates to form a new photon, which is ultimately absorbed by the electron.>> <<I am sure that in a few more years, the theoretical and experimental numbers for the magnetic moment of an electron will be worked out to still more places. Of course, I am not sure whether the two values will still agree. That, one can never tell until one makes the calculation and does the experiments.>> Well, 20 years later, they still agreed all right, up to the 12th decimal place... are you really sure we need a better theory Robin? ;-) Cheers, Michel 2009/3/2 <[email protected]>: > In reply to Michel Jullian's message of Mon, 2 Mar 2009 09:55:37 +0100: > Hi Michel, > [snip] >>Robin, >> >>I may be wrong but all this sounds complicated and ad hoc, compared to >>the standard quantum electrodynamics theory, which, although it often >>goes against common sense (e.g. the "preposterous" things I >>mentioned), does predict things nicely from a tiny set of rules. > > Does it really? I must admit to never having been deeply involved in quantum > theory, but I get the impression, looking in from the outside, that in > practice > "adjustments" are usually made until the "right" result is obtained. > >> >>For example, to go back to the subject of your original question, can >>Mills predict the next decimal places for the electron's intrinsic >>magnetic moment (presently 12 or so) > > I doubt very seriously that there is a single physical quantity anywhere on > Earth that can be measured with such accuracy/precision, for two reasons. > > 1) Measurement implies comparison with a standard, and I don't think we have > any > standards that accurate/precise. > > 2) The measurement instruments themselves would need not to vary in *any* of > their critical parameters by that degree of precision during the measurement > process. I find it very hard to believe that this is the case. Furthermore the > accuracy of those parameters also needs to be known with that degree of > precision, otherwise the number is meaningless, even if the precision were > valid. > > Here I use accuracy to describe the absolute value of a measurement, and > precision to describe the number of decimal places to which the value is > known. > > However, to answer your question, I think the answer is no, but then he also > doesn't (yet) take many of the smaller effects into account that influence > precision at that level. IOW it doesn't necessarily mean that his theory would > fail at that level if he were to try. > > BTW you shouldn't judge Mills by any representations I may make. > [snip] > Regards, > > Robin van Spaandonk > > http://rvanspaa.freehostia.com/Project.html > >
