Einstein's 1916 general theory of relativity is now nearly one hundred years old. Einstein originally designed the 1916 theory to reduce to the physics of SR over small regions, so that he wouldn't have to rederive all physics from scratch using curved-spacetime arguments.This shortcut meant that the resulting general theory ended up with internal conflicts between Einstein's principle of equivalence and special relativity (1960), disagreed with quantum mechanics (1970s), and led to a heavily stratified system of physics with different rules operating at the scales associated with quantum mechanics, special relativity, general relativity and cosmology. In 2015 we still have no accepted method of reconciling GR1916 with quantum theory.
Replacing the "flat" SR Minkowski metric with a more sophisticated relativistic acoustic metric seems to solve all these problems.
Making such a big change to an established theory that so many people have invested in would cause disruption and upheaval ... but other than these "social" and "pragmatic" objections, are there any scientific reasons why we shouldn't be using this sort of alternative general theory?
Figure 2 from the paper, showing the current stratification of inertial/gravitational physics, and the step-by-step unification proposed in the paper as part of a switch to a relativistic acoustic metric.
The large review paper on acoustic metrics and QM cited in the paper:
Article Analogue Gravity
Hawking's 2014 suggestion of a resolution to the black hole information paradox:
S. W. Hawking Information Preservation and Weather Forecasting for Black Holes (2014) arXiv:1401.5761
"... A different resolution of the paradox is proposed, namely that gravitational collapse produces apparent horizons but no event horizons behind which information is lost. This proposal is supported by ADS-CFT and is the only resolution of the paradox compatible with CPT. ... "
Hawking suggests removing the full event horizons of GR1916, and replacing them with "apparent" horizons, which share some of the same features, but allow information to migrate outwards. The additional suggestion that that the interior of the hole may be turbulent and chaotic can then be used to allow GR to "save face", as, although "things" would be moving across the horizon in both directions, the appearance of the "things" that were emitted would not necessarily resemble the "things" that had previously entered - information might be so scrambled that although the relationship between patterns of ingoing and outgoing massenergy would be deterministic, it would appear random and be functionally unpredictable (like weather on Earth).
The point about "practical" unpredictability seems to me to be more about addressing human psychology than fundamental physics issues. I don't see why everything that is reemitted by a hole should be untraceable to infallen information (as even complex chaotic systems can have islands of calm, that might allow a recognisable pattern to infall and be reemitted almost immediately). I think that the invocation of chaos theory is there to prevent GR looking as if it is obviously being violated. I'm not convinced that he universe cares much about the distinction.
Oh, and how do we modify GR1916 so that it has "apparent" horizons instead of "full event horizons"? With a relativistic acoustic metric! :) Ha.
Article Information Preservation and Weather Forecasting for Black Holes
The metric of general relativity (Schwarzschild metric) cannot explain Hydrogen spectra. The metric of periodic relativity can explain Hydrogen spectra.
Article Hydrogen spectra using Einstein's field equations
Acoustic metric or analogue gravity model is new concept to look what is actual nature of the gravitation/metric. The model could be first step toward the desired merge of GR and QM, especially in the veiw of the BOse Einstein Condensate (BEC) which has desent correspondance to the model. However the actual step to merge it with QM yet to be made.
BTW there is still no direct correspondence of the GR field equation to the equations of acoustic metric. It only allows to reproduce specific metrics of GR with precision to conformal factor.
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