Posted: Sep 15, 2011 8:57 pm
by zaybu
twistor59 wrote:
zaybu wrote:

This paper talks about "first quantization" to describe photons. Just elemerntary stuff.


If you think that applying first quantization to photons is "elementary", then you have a different definition of elementary to the one I have !


It's elementary in the sense that there hasn't been any new development in QM since the 1930's. Omitting the advancement in QFT from 1930 to 1970 would be like studying math without studying any math from calculus and on. Your grasp of the subject would be quite limited. How could you discuss renormalization, gauge invariance, higgs mechanism or Wilson loop? Yet these are the backbones of the subject matter.

zaybu wrote:
To be honest, twistor, if you want to study QFT, Weinberg is THE book. All that stuff you linked to is passé.


That's a rather off-hand dismissal of some interesting and controversial discussions, whereas in fact the quantum field theory you are presenting as the shizzle forms the basis of first year postgraduate theoretical physics courses.


No it wasn't. You linked to papers that had very little to do with your concept of "localizability". Just basic papers making a connection between classical physics (Maxwell equations) to QM. I still have no clue with what you mean with your concept. Are there equations that describe that concept? If you do, please let me know.




Did you read what I wrote above in the first post of this thread ? You get exactly the same discrete behaviour (flashes building up the interference pattern) if you treat the incident field as purely classical ! The flashes do not provide a proof of the quantum nature of the electromagnetic field - however other things do provide such proof.


I disagree. The graininess demonstrates that releasing one photon at a time shows their particle nature. No wave model can explain that.


zaybu wrote:
twistor59 wrote:
Incidentally, do you think that two electrons really exchange photons when paticipating in the electromagnetic interaction ?


That's what QED says. Do you have a better theory?


QED says nothing of the sort. It merely says that one way (perturbation theory) of computing the effects of the interaction is to treat the system as if virtual quanta are exchanged. However this is merely a calculational device. If you could solve the nonlinear interaction exactly, there would be no need to invoke virtual particles. The electromagnetic field, however, does allow real excitations, namely the photons that we can measure.


QM is based on several assumptions such as operators are observables, or that the probability is the square of the amplitude, etc. The point is that this assumption of exchange particles explains many phenomena. The thousands of Feynman diagrams that explain millions of interactions observed in the many supercolliders across the planet wouldn't make any sense without that assumption. That's why it's called high energy particle physics, and the Standard Model describes the fundamental particles of nature.