Gravity Emerges From Neutrinos ?

[Rade]

I searched this section of the forum, and could find no threads that seem to discuss this paper. This paper was placed on ArXiv in 2008, I do not know if it was published:

http://arxiv.org/PS_cache/arxiv/pdf/0812/0812.2696v1.pdf

 

If not, I would like this thread to discuss this paper. It makes a very interesting claim that gravity on the large Cosmology scale emerges from neutrinos.

 

Then, I would like to discuss how this idea could be expanded to the quantum scale :), if at all. I mean, is it possible that the matter and antimatter neutrinos observed during isotope radioactive decay could relate to "quantum gravity", if it exists ?

 

==

 

I did find on the internet some answers posted to questions by the author of the paper, from Discover Magazine. I list them below for anyone that will take time to read the paper and may have questions about it--best to get answers direct from the author:

 

From Discover Magazine:

 

Bob McElrath Says:

December 28th, 2008 at 7:09 am

 

I’ll try to answer a couple questions here:

 

1) The 10^{-17}K number in the Kohn-Luttinger paper comes from the usual

assumption that Delta x = 1/p (the de Broglie wavelength), which I

argue in the second section is not correct for cosmological relics.

Instead one must use Eq.5 or Eq.6, for which (inserting the neutrino

self-interaction cross section) one derives T < M_W as the transition

temperature (if you insist on stating it as a temperature). Note that

the K-L 10^{-17} transition temperature is correct for electrons,

because electrons have a Coulomb pole, and remain localized to their de

Broglie wavelength due to the strong scattering implied by this Coulomb

pole. In other words in terms of the QM barrier penetration

coefficients, T=0 and R=1 for electrons while T=1 and R=0 for

cosmological relics (T=transmission, R=reflection). Cosmological relics

are undergoing index of refraction physics, while electron scattering is

dominated by elastic scattering, which causes localization. As such, I

doubt that my results imply anything useful for high T_c

superconductors or any observable phenomena in condensed matter physics.

 

2) On universal couplings: I agree it is far from obvious that this will

happen. I do have an idea for how they will arise that will appear

soon. I believe this system MUST have universal couplings, otherwise

one could easily show that the Standard Model (due to background

neutrinos) is incompatible with gravitational equivalence principle

tests, even if gravity is a separate force. All particles (including

photons and gluons) do couple to the neutrino-graviton: the couplings

are 4-point operators which may arise at 1- or 2-loop.

 

3) On Weinberg-Witten: Sean, sure one can choose to work in a

diffeomorphism invariant formalism, but then one must add breaking terms

which correspond to the fact that particles can move faster than the

speed of light in the medium, and that G_N is varying. I cannot perform

a coordinate transformation to get to a region of space with a different

G_N: I would find my covariant stress tensor is not conserved, which is

one of the assumptions of Weinberg-Witten, and therefore their theorem

is not applicable here.

 

Bob McElrath Says:

December 28th, 2008 at 12:26 pm

 

The Fermi temperature for this system is just T_F=E_F/k = sqrt(m^2+p_F^2)/k which is ~10^{-3} eV today. The critical temperature for this phase transition is ~ M_W, which is not the same as the Fermi temperature. It is this critical temperature that Kohn-Luttinger calculate as 10^{-17} K, which is relevant for an atomic or electronic gas with Coulomb interactions.

 

I did not quote a critical temperature and left it as a cross section in my paper because this requires knowing the cross section as well as n(T), which are model-dependent. e.g. the cross section depends on particle content and n(T) (may) depend on Hubble expansion, depending on your assumptions.

 

# 23. Bob McElrath Says:

December 28th, 2008 at 3:55 pm

 

I am proposing a new mechanism for the quantum liquid transition in Sec.2. In the RG approach, Delta x of the state does not enter the problem at all, and the only scale is the momentum p (and de Broglie wavelength), so the RG treatment only predicts the transition temperature if Delta x ~ 1/p for all time, which is definitely not satisfied for cosmological relics.

 

Fundamentally what is required for a superfluid is wave function overlap. This is satisfied by the time-expansion of wave packets, and is not described at all by the RG.

 

For the record, when I use the phrase “quantum liquid”, I mean Delta x > n^{-1/3}, and that’s all. By “Super-fluid” I mean the existence of a lower energy ground state than the free particle state. (with or without the classic consideration of viscosity)