Preprint Stress Energy Tensor Study in Fluid Mechanics
(french version is available on my research profil)In my last article "The stress energy in fluid mechanics", I explain what is current researches about fluid space-time.
On the one hand, Franck Delplace thinks that this viscosity is high. However, I do not find that coherent at all, in the sense that if a high viscosity existed, the bodies that move in space-time would be slowed by this viscosity. It would be more generally a Newtonian fluid (ie a non-turbulent fluid with a viscosity), and more precisely, a Newtonian superfluid (a non-turbulent fluid with a viscosity almost zero).
I am not an astrophysicist, but that can explain the phenomenon described by Stephano Liberatti and Luca Macione: "they thought that high energy photons that travel a great distance lose a large fraction of their energy". This loss of energy, tiny, is due to this very low viscosity, which has an influence on the movement of the bodies.
In the case of high gravity (as at the beginning of a black hole) space-time bends so much that the photons are "swallowed" in the black hole. In a certain way, space-time, which is globally a Newtonian superfluid, becomes a non-Newtonian superfluid (a turbulent fluid with a near-zero viscosity). A team of physicists then noticed that the lower the viscosity, the more the fluid is turbulent. This is observed at the beginning of a black hole, which is also easily comparable to the great entropy that has black holes.
In conclusion, I think that space-time must be superfluid. If he had a high viscosity, it would risk complicating the theoretical calculations and would require reviewing all the physics, which is not necessary at all. Space-time is a Newtonian superfluid, which becomes non-Newtonian when the gravitational force becomes very large (black hole, neutron star etc ...).
Superfluid have more coefficient of viscosity so viscosity increase and viscosity also depends on general relativity and temperature.
Dear Roman, the idea of treating the general relativity as a fluid dynamics is good, but is partially undefined. Many are the characteristics that are possible.
If you take the hydrodynamic equivalence of quantum mecanics you have a fluid dynamics with the right parameters that fit with the quantum mechanics and hence the right model among the possible ones of the fluid dynamics.
See for instance the paper of Roumen Tsekov et al.: Relating quantum mechanics to hydrodynamic turbulence. EPl, 122 (2018) 40002
It might be useful to study T. Damour's thesis: http://www.ihes.fr/~damour/Articles/these1.pdf (this is the first chapter; the others can be found in http://www.ihes.fr/~damour/Articles ).
Dear Roman Baudrimont ,
In recent work, I have found that the acceleration due to the gravity of an object with radius a and mass m is given by the relation g=(6 pi ^2 c) (a/m) eta, where eta is the shear viscosity coefficient and c is the speed of light in vacuum.
How does this relation matter to you?
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