spencert%rpi.csnet@csnet-relay.arpa (08/14/85)
From: Thomas Spencer* <spencert%rpi.csnet@csnet-relay.arpa> I am given to understand that Qunatum Electrodynamics (QED) makes a prediction about the value of the fine structure constant. Furthermore, it is difficult but possible to derive a numerical for this constant. This derivation supposedly has been done to some extent and the theoretical value has been determined to about 10 significant figures. The fine structure constant can be measured from Hydrogen spectra to about the same accuracy and the theoretical and measured values agree. Question: Is this correct ? If so, could someone explain approximately how one calculates the fine structure constant. (I am looking for an explanition of the level of: Solve P.D.E. #1 Stuff #1. Solve P.D.E. #2 Stuff #2. Integrate the difference in solutions over everywhere. Or something like that ) Thank you. Tom Spencer
tan@ihlpg.UUCP (Bill Tanenbaum) (08/17/85)
> From: Thomas Spencer* <spencert%rpi.csnet@csnet-relay.arpa> > I am given to understand that Qunatum Electrodynamics (QED) > makes a prediction about the value of the fine structure constant. > Furthermore, it is difficult but possible to derive a numerical for > this constant. This derivation supposedly has been done to some extent > and the theoretical value has been determined to about 10 significant figures. > The fine structure constant can be measured from Hydrogen spectra to about > the same accuracy and the theoretical and measured values agree. > > Question: Is this correct ? -------------- No. The fine structure constant is an arbitrary constant in Q. E. D. Of course, if the constant were much larger than it is, the perturbation expansion series given by Q. E. D. would not converge, and it would be difficult or impossible to calculate anything. -- Bill Tanenbaum - AT&T Bell Labs - Naperville IL ihnp4!ihlpg!tan