Sure. I’d say that property is a lot stronger than “velocity exists as a concept”, which seems like an unobjectionable statement to make about any theory with particles or waves or both.
I guess there’s “velocity exists as a description you can impose on certain things within the trajectory”, and then there’s “velocity exists as a variable that can be given any value”. When I say relativity asserts that velocity exists, I mean in the second sense.
In the former case you would probably not include velocity within causal models of the system, whereas in the latter case you probably would.
As far as I know, condensed matter physicists use velocity and momentum to describe quasiparticles in systems that lack both Galilean and Lorentzian symmetry. I would call that a causal model.
Yes, it’s exactly the same except for the lack of symmetry. In particular, any quasiparticle can have any velocity (possibly up to some upper limit like the speed of light).
Sure. I’d say that property is a lot stronger than “velocity exists as a concept”, which seems like an unobjectionable statement to make about any theory with particles or waves or both.
I guess there’s “velocity exists as a description you can impose on certain things within the trajectory”, and then there’s “velocity exists as a variable that can be given any value”. When I say relativity asserts that velocity exists, I mean in the second sense.
In the former case you would probably not include velocity within causal models of the system, whereas in the latter case you probably would.
As far as I know, condensed matter physicists use velocity and momentum to describe quasiparticles in systems that lack both Galilean and Lorentzian symmetry. I would call that a causal model.
Interesting point. Do the velocities for such quasiparticles act intuitively similar to velocities in ordinary physics?
Yes, it’s exactly the same except for the lack of symmetry. In particular, any quasiparticle can have any velocity (possibly up to some upper limit like the speed of light).