Optical gravity works badly

We introduced optical gravity last year as a way to interpret general relativity. Unfortunately, the optical interpretation only works well for static gravitational fields. In astronomy, we witness (almost) static gravitational lenses caused by galaxies and galaxy clusters. Optics is a nice way to interpret what we see.

We conjectured that the optics of a static Schwarzschild black hole would reflect all incoming waves out before the horizon. That is not true. Several authors have calculated the reflection, or scattering, using the wave equation for curved spacetime. The result is that for short wavelengths and close to the horizon, the scattering is negligible.

There is only significant scattering for wavelengths of the Schwarzschild radius or longer.

If the system is dynamically changing, calculating the optics of spacetime is awkward. For example, the exact location of an event horizon depends also on future events. We do not know the optical density of spacetime before we know the future, too.

The model of a "frozen star", where the interior of a horizon is frozen in time, suffers from the same problem in dynamic systems. If we do not know where the horizon is, how does the material inside the horizon know when exactly it should freeze?

It looks like we have to admit that an astronaut can fall through an event horizon.

We still have not found a way to make the Hawking radiation hypothesis work. Thus, we cannot assume that the Hawking evaporation of the black hole will prevent the astronaut from falling through the horizon.

For a freely falling observer, the event horizon looks completely normal, slightly curved spacetime. There is no drama there, no infinite forces or energies. We would need some unknown physical mechanism to stop the extension of the spacetime manifold inside the event horizon. There seems to be no reason why the astronaut cannot keep living and pass the horizon.

A singularity, on the other hand, is very dramatic. We cannot extend the spacetime manifold smoothly past a singularity.