Author Topic: Superfluid vacuum sound waves  (Read 3208 times)

Offline Higher Love

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Superfluid vacuum sound waves
« on: 01/28/2018 06:12 PM »
I read a discussion on this forum about how in the Superfluid vacuum theory there are sound waves that propagate in the vacuum.

By Rodal:
"There are several theories of a superfluid vacuum.  These theories have a "speed of sound" of the vacuum superfluid equal to (in the simplest theories) or higher than the speed of light.

The speed of sound in the superfluid vacuum can be associated with quasiparticles which are thus phonons: quanta of sound waves.  The superfluid vacuum theories thus have "sound waves" in addition to "gravitational waves".   

One can think of the speed of sound of the vacuum as being associated with a (very large value) bulk modulus of elasticity (and density) of the superfluid vacuum, but these theories usually discuss the speed of sound (*) of the vacuum in terms of vacuum energy considerations and not specifically in terms of a bulk modulus of elasticity of the vacuum superfluid."


I wanted to ask, what that sound field would be described as?
How would particles emit sound? What would virtual phonons be in that case?

Offline Higher Love

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Re: Superfluid vacuum sound waves
« Reply #1 on: 03/06/2018 05:45 PM »
Which book/source discusses this:
"There are several theories of a superfluid vacuum.  These theories have a "speed of sound" of the vacuum superfluid equal to (in the simplest theories) or higher than the speed of light."
If there are several types of SVT talking about this, it should be accessible via a book or a research paper.

Thank you. :)

Offline morganism

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Re: Superfluid vacuum sound waves
« Reply #2 on: 03/08/2018 07:46 AM »
Reading one now called " A superfluid universe" by Kerson Huang. Leader in the field.

Interesting so far, i didn't realize photons had mass in superconductors either.

Offline Higher Love

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Re: Superfluid vacuum sound waves
« Reply #3 on: 03/10/2018 12:26 PM »
Hello, morganism. :) Hope you are well.

Is the book talking about sound in the superfluid vacuum so far?

Offline Higher Love

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Re: Superfluid vacuum sound waves
« Reply #4 on: 03/14/2018 07:05 PM »
What interaction would the phonons carry/mediate if they were considered a fundamental particle? What is the charge they would act on? :)

Thank you.
« Last Edit: 03/14/2018 07:11 PM by Higher Love »

Offline Higher Love

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Re: Superfluid vacuum sound waves
« Reply #5 on: 03/19/2018 01:25 PM »

Offline Higher Love

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Re: Superfluid vacuum sound waves
« Reply #6 on: 03/22/2018 08:09 PM »
I read about Global U(1) symmetry being the simplest symmetry in superfluids. What other symmetries are associated with superfluids?


Offline Higher Love

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Re: Superfluid vacuum sound waves
« Reply #7 on: 03/24/2018 03:01 PM »
I also read some of the book "Introduction to superfluidity" by Andreas Schmitt. I just wanted to ask if the phonons in the superfluid vacuum would also be gauge bosons with spin 1.

Thank you.

Offline Higher Love

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Re: Superfluid vacuum sound waves
« Reply #8 on: 03/25/2018 06:26 PM »
I also found this article, though its not about the superfluid vacuum:

https://pdfs.semanticscholar.org/92a1/327412b35b7a9649ec477a3d580092472094.pdf
"Possibility of Sound Propagation in Vacuums with the Speed of Light"

Offline Higher Love

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Re: Superfluid vacuum sound waves
« Reply #9 on: 03/25/2018 09:17 PM »
Could anyone please explain to me how the sound waves would be propagated in the superfluid vacuum. How are they connected to the vacuum energy?

Thank you. :)

Offline Higher Love

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Re: Superfluid vacuum sound waves
« Reply #10 on: 03/28/2018 01:54 AM »
How is this formula for the speed of sound derived:

c = (n/m) ∂U/∂n

where

U = vacuum energy density as a function of the quasiparticle density
n = quasiparticle number density
m = bare mass of quasiparticle

one may infer from this an equivalent bulk modulus of elasticity of the superfluid vacuum (which follows readily from the fact that the bulk modulus of elasticity for a hyperelastic material is the second derivative of the strain energy density with respect to the volumetric logarithmic strain):

c = (1/ρ) ∂U/∂ε
     = Ks / ρ


Is there a book that explains the derivation of this formula?

Thank you.

Offline Higher Love

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Re: Superfluid vacuum sound waves
« Reply #11 on: 03/31/2018 05:31 AM »
Could someone please help me with these questions? How are sound waves propagating in the superfluid vacuum?
Thank you so much!

Based on what Dr Rodal said:

"There are several theories of a superfluid vacuum.  These theories have a "speed of sound" of the vacuum superfluid equal to (in the simplest theories) or higher than the speed of light.

The speed of sound in the superfluid vacuum can be associated with quasiparticles which are thus phonons: quanta of sound waves.  The superfluid vacuum theories thus have "sound waves" in addition to "gravitational waves".   

One can think of the speed of sound of the vacuum as being associated with a (very large value) bulk modulus of elasticity (and density) of the superfluid vacuum, but these theories usually discuss the speed of sound (*) of the vacuum in terms of vacuum energy considerations and not specifically in terms of a bulk modulus of elasticity of the vacuum superfluid."

I would appreciate if the source of this/book is pointed out to me too. Thank you.
« Last Edit: 03/31/2018 07:30 PM by Higher Love »

Offline Higher Love

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Re: Superfluid vacuum sound waves
« Reply #12 on: 03/31/2018 11:12 PM »
I purchased Kerson Huang's book "A Superfluid Universe". I hope it answers some questions or me. :)