UPDATE November 13, 2023: The question of Lorentz covariance of general relativity is still unclear. On November 7, 2023 we tentatively proved that the Einstein equations have no solution for any realistic physical system. The question of Lorentz covariance becomes partially moot.
We are undecided about linearity/nonlinearity of gravity.
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What is wrong in general relativity
1. The Einstein field equations are not Lorentz covariant. They calculate a wrong orbit for a test mass m in the case where the central mass M moves. The reason is that the field equations think that the kinetic energy of M gravitates like the rest mass of M, while the gravitational pull really is fourfold, if m passes past M.
2. The steepening of the gravity potential in the Schwarzschild solution is highly suspect: it leads to very strange results. The potential probably has to be newtonian.
3. General relativity does not satisfy a weak equivalence principle. Though this is not really wrong, since we do not think that gravity should satisfy it.
4. The concept of a "metric" handles accelerating gravity sources in a wrong way. We may be forced to abandon the concept of a metric and treat the interactions between the test mass m and the parts of M "privately".
5. If gravitational waves truly can shorten spatial distances between two events, they open a way for superluminal communication. That has to be prevented.
6. The Gödel universe and the Kerr solution seem to contain timelike loops. That is unlikely to be a physically correct prediction.
7. The claim that spacetime can be "curved" and that its topology can differ from the Minkowski space is a bold hypothesis, for which we have no evidence whatsoever. The hypothesis is almost certainly wrong.
What is correct in general relativity
1. In the weak field, the Schwarzschild solution seems to be right. It agrees with our own Minkowski & newtonian gravity model.
2. The geodesic equation calculates orbits correctly for a metric (if there exists a correct metric).
3. Linearized Einstein equations calculate the energy content of gravitational waves correctly.
All "exotic" black hole physics is incorrect
1. It is very unlikely that a one-way membrane like the event horizon, can exist physically. The system probably "freezes" before such a strange object can form.
2. A singularity does not make much sense. The freezing process probably prevents a singularity from forming.
3. Black hole thermodynamics is entirely wrong. There is no need for a black hole to have large entropy.
4. Hawking radiation does not exist. There is no black hole information paradox.
Conclusions
General relativity got right weak field gravity effects, like the bending of a ray of light as it passes the Sun, and gravitational waves. There has to be some truth to the Einstein field equations, even though they handle moving masses incorrectly. We have to analyze what exactly is right in the field equations. Equivalence principles might be the reason why the field equations get some things right.
In July 2023 our goal was to find out if we can disassemble a black hole by spinning it fast. We now know more about gravity, and can try to resolve the question.
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