> On 11 Jan 2019, at 10:03, Philip Thrift <cloudver...@gmail.com> wrote: > > > > On Thursday, January 10, 2019 at 8:27:20 PM UTC-6, Bruce wrote: > On Fri, Jan 11, 2019 at 12:18 PM Brent Meeker <meek...@verizon.net > <javascript:>> wrote: > On 1/10/2019 4:21 PM, John Clark wrote: >> So even Feynman knew that there was no theoretical value for the FSC, alpha. >> >> No, he knew very well there was a theory that could come up with a value >> because his own Feynman Diagrams could do it. But what he didn't know and >> what nobody knows is why his theory came up with that particular pure number >> when he never specifically stuck that number into the rules on how the >> diagrams should operate. > > The fine structure constant is e^2/hbar*c. Those three values are measured > independent of any Feynman diagrams of quantum field theory. The calculation > using Feynman diagrams is of the anamolous magnetic moment. A correction to > the value of g that depend on relativistic effects (hence the occurence of c > in the denominator). The anamolous magnetic moment can be measure > experimentally and using Feynman's diagrams and the measured values of e, > hbar, and c a value can be calculated that includes the relativistic effects > of quantum field theory. That's why the agreement with measurement is > significant. > > Right. The relation between fundamental physical constants, alpha = > e^2/hbar*c, is the closest one gets to a "theoretical" value for the FSC. But > that defines it in terms of other measured quantities. (Except that these > days, c is a defined number, not a measured physical parameter.) The CODATA > group use these theoretical relationships between constants, together with > the best available measurements, to make simultaneous fits to all the > constants and the data.That is where independent, "best values" for these > parameters come from. It is using these in the Feynman diagram calculation of > corrections to g-2 that gives the remarkable agreement between theory and > experiment. The point, though, is that the value of the FSC used in > calculating g-2 must be obtained independently of the g-2 measurement or else > it is not a test of QED.. Conversely, of course, the g-2 measurement can be > use to estimate the FSC independently of other measurements. > > Bruce > > > Brent > > > > > > > As the Robert Geroch, James Hartle paper points out > > the issue of whether the existence of an algorithm to implement a theory > should be adopted > as a criterion for acceptable physical theories. > > if you want measurable constants to be computable, adopt a theory that does > so.
Some constant might be intrinsically not computable. Normally, the physical laws should at some point take into account the probability of (self) halting, which would introduce a non computable constant in nature, although it would be computable from the halting oracle. Mechanism prevents the physical reality from being entirely computable. I suspect Planck constant to be not computable, because if we extract QM from arithmetic, the Planck constant might very well related to the mechanist substitution level. We cannot choose a theory according to our metaphysical state, especially in metaphysics. It has to be corroborated by the facts. Bruno > > - 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 everything-list+unsubscr...@googlegroups.com > <mailto:everything-list+unsubscr...@googlegroups.com>. > To post to this group, send email to everything-list@googlegroups.com > <mailto:everything-list@googlegroups.com>. > Visit this group at https://groups.google.com/group/everything-list > <https://groups.google.com/group/everything-list>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
