On Friday, January 11, 2019 at 2:46:35 PM UTC-6, Brent wrote: > > > > On 1/11/2019 6:01 AM, John Clark wrote: > > On Thu, Jan 10, 2019 at 8:18 PM Brent Meeker <[email protected] > <javascript:>> wrote: > > * > The fine structure constant is e^2/hbar*c. Those three values are >> measured independent of any Feynman diagrams* >> > > Absolutely correct. So if you use Feynman diagrams to predict what some > physical system is going to do, such as a physical system of 2 electrons > being hit by a photon of light with a wavelength small enough to contain > enough energy to prevent the electrons repulsion, then you'd better get a > number very close to the Fine Structure Constant. If you don't then Feynman > Diagrams aren't any good. > > They didn't use 12,672 Feynman Diagrams because they wanted to know what > the Fine Structure Constant was, they already knew what that number was > to many decimal places from exparament, they used 12,672 Feynman Diagrams > because they wanted to see if Feynman Diagrams worked. And it turned out > they worked spectacularly well in that situation, and that gives scientists > great confidence they can use Feynman Diagrams in other situations to > calculate what other physical systems will do that involve the > Electromagnetic Force. > > > There's always an interplay between theory and experiment. It's > completely analogous to Maxwell's discovery that light is EM waves. There > were already experimental values of the permittivity and permeability of > the vacuum and there were values for the speed of light. Maxwell showed > that his theory of EM predicted waves and using the permittivity and > permeability values the speed of the waves matched that of light. Now the > speed of light is a defined constant and so are the permittivity and > permeability of the vacuum. So the connecting of the three values by a > theory allows their values to be defined. In the case of the anomalous > magnetic moment of the electron, hbar and c are already defined constants. > So quantum field theory (for which Feynman diagrams are just a > calculational tool) linked them and e to g. > > Brent > >
If Feynman Diagrams (tools) are sufficient (to match experimental data) then Quantum Field Theory can be thrown in the wastebasket. - pt -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
