Phonon Lorentz Invariance in Superfluids - Papers?

In summary, this paper discusses the possibility that phonons in a Bose–Einstein condensate may exhibit Lorentz invariance in the low momentum limit, which is interesting because it suggests that the Lorentz invariance observed in quantum field theory at lower energies might actually be due to a breaking of Lorentz invariance at the Planck scale.
  • #1
philton
10
0
It is said phonon(not photon) in superfluid experiments could also produce similar upper-limit speed effect which I'm not sure if that's also Lorentz invariant.

Another problem is that I can't dig out those paper that demonstrates this kind of effect. Anyone ever seen any of this paper? Thanks..
 
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  • #2
philton said:
It is said

Where? Is this something in the paper you can't dig out?

Bear in mind that, without a reference, it's going to be very difficult to answer your question.
 
  • #3
PeterDonis said:
Where? Is this something in the paper you can't dig out?

Bear in mind that, without a reference, it's going to be very difficult to answer your question.

Oops, thanks for the remind:
ACOUSTICS IN BOSE–EINSTEIN CONDENSATES AS AN EXAMPLE OF BROKEN LORENTZ SYMMETRY
http://arxiv.org/pdf/hep-th/0109033v1.pdf

MATT VISSER \/ CARLOS BARCELO said:
In particular, acoustics in Bose–Einstein condensates has the interesting property that at low-momentum the phonon dispersion relation can be written in a “relativistic” form exhibiting an approximate “Lorentz invariance”
 
Last edited:
  • #4
philton said:
ACOUSTICS IN BOSE–EINSTEIN CONDENSATES AS AN EXAMPLE OF BROKEN LORENTZ SYMMETRY

Ok. Note that they put "Lorentz invariance" in quotes; the "invariance" is in terms of the speed of sound in the material, not the speed of light, and it only applies for phonons of sufficiently low momentum. The speed of sound in a material is not Lorentz invariant (in the usual sense of invariance in terms of the speed of light); it will be different in a frame in which the material is moving than it is in a frame in which the material is at rest. So the phonon behavior discussed in this paper is not Lorentz invariant in the usual sense; the paper appears to be writing down all its equations in the rest frame of the material.

The interest of this model is not that phonons are actually Lorentz invariant; it is that the equations in the low momentum limit have the same form as Lorentz invariant equations in quantum field theory, so that the form of the equations for the breaking of the "Lorentz invariance" of phonons as you go to higher momentum might give suggestions for how a hypothesized breaking of actual Lorentz invariance at or near the Planck scale could work.
 

1. What is Phonon Lorentz Invariance in Superfluids?

Phonon Lorentz Invariance is a principle that states that the laws of physics governing the behavior of phonons (quantized sound waves) in a superfluid are the same for all observers, regardless of their relative motion.

2. Why is Phonon Lorentz Invariance important in the study of superfluids?

Phonon Lorentz Invariance is important because it allows for a consistent and universal understanding of the behavior of phonons in superfluids, which is crucial for accurately predicting and describing their properties and interactions.

3. How is Phonon Lorentz Invariance tested in experiments?

One way to test Phonon Lorentz Invariance in superfluids is through precision measurements of the speed of sound, which should be the same for all observers regardless of their relative motion. Other experiments involve studying the behavior of phonons in different reference frames and comparing the results.

4. What are some potential implications of violating Phonon Lorentz Invariance in superfluids?

If Phonon Lorentz Invariance is found to be violated in superfluids, it could have significant implications for our understanding of the fundamental laws of physics. It could also lead to new insights into the behavior of superfluids and potentially open up new avenues for research.

5. Are there any current research developments or controversies regarding Phonon Lorentz Invariance in superfluids?

There have been recent studies suggesting that Phonon Lorentz Invariance may be violated in certain types of superfluids, which has sparked debate and further research in the field. However, there is still a lack of consensus and more research is needed to fully understand the implications of these findings.

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