Klein-Gordon equation: can superluminal phase velocity violate causality?

Join the discussion
Registration is free. Start your own thread to ask a follow-up.
Sign up Log in
32 replies · 6K views
vanhees71 said:
Here Sommerfeld's argument cannot be applied ...
It would be nice if you could present details of an example were the Sommerfeld's argument can be applied.
 
Physics news on Phys.org
Avodyne said:
I continue to claim that the inapplicability of Sommerfeld's argument is due to the form of the KG dispersion relation (with branch points on the real axis), and not due to the singular initial condition.
I'm not sure what exactly is the Sommerfeld's argument, but there is a very general proof in
A. Bers, R. Fox, C.G. Kuper and S.G. Lipson,
a chapter in the book C.G. Kuper and A. Peres (eds), "Relativity and Gravitation" (Gordon and Breach, 1971)
for which branch points on the real axis are not a problem. The contour of integration over frequency avoids all singularities on the real axis.
 
Last edited:
Demystifier said:
@vanhees71, have you noticed that your proof in #28 is almost identical to my proof in #21?
Argh, I've not seen this posting. It's indeed identical. Sorry for that.