The analogy between the quantum vacuum and condensed matter could give an insight into the trans-Planckian physics since it provides examples of the physically imposed deviations from Lorentz and other invariances at higher energy. This is important in many different areas of high energy physics and cosmology, including possible CPT violation and black holes, where the infinite red shift at the horizon opens a route to trans-Planckian physics.So the whole book advocates symmetry emergence in the local world of quasiparticles in the system, but they won't consider the varying speed of light cosmology? Why? Because some relativist told them it was naughty? Section $4.3.3$ bears the title is the speed of light a fundamental constant, but for some reason the cosmology is skipped in this section and we learn only that 3He-A for an external observer (meaning in the laboratory) has an analogue speed of light ranging from $0.03$ to $100$ $ms^{-1}$. Then again, the book does have some nice sections on vortices, and one has to admire the fluency with which Volovik switches between his external and internal viewpoints.

8 years ago

Volovik is wise :)

ReplyDeleteThe changing speed of light must be very small, if it changes. And the DE problem and universe expansion is about 70% of the energy, that is very big part. Can a small change in the speed of light really make up for that? Remember this expansion is measured (and calculated from missing explanations?). Also the math should be looked over, so it is right.

I think the light can change but can that a small change really give that big number for expansion?

Ulla, I think we all see this a little different; but to me, "variable time" means rewriting GR so that curvature only appears in time or space-time components; it does not appear in space-space components.

ReplyDeleteIf you do this, you find you can assume a flat background space. Gravity becomes a way of defining relative changes to the velocity (not just "speed") of light. To see this in the context of the Kerr geometry (rotating black hole) read the very informative and easy to understand article "The River Model of Black Holes" gr-qc/0411060.

In that way a gravitational lens would be inumeros different spacetime sheets all with a bit different time? Then the light must jump from one sheet to another?

ReplyDeleteWhat relation has time and light?