# Measurement of singularity as a particle inside event horizon

1. Jun 9, 2014

Although the subject line might seem to put this question inside general relativity, the reason I put it in quantum physics is because I would like to know what happens when one treats a singularity as a particle. Obviously from outside the event horizon, one cannot do this, but inside the event horizon the situation is different. Nonetheless, if anyone thinks the thread should be moved, I would have no objection.

I know that the current physics largely breaks down at the singularity, but assuming that some sort of physical laws will eventually be formulated that can deal with the presence of the singularity, the first question which arises is that of measurement.

Inside the event horizon, a direct measurement of the singularity by bouncing photons off of it would be impossible. However, the behavior of photons and other particles around the singularity would be measurable: could these provide a means for an indirect measurement of the singularity?

If a measurement is indeed possible, what would be the status of the uncertainty principle? Is the fact that σx =0 give an absurdity for σp or does it just mean that we cannot know anything about the momentum? Wouldn't there be any finite bound on the spectrum of the momentum?

Although outside the event horizon we can know the mass of the black hole, an observer inside the event horizon could not measure the size of the event horizon to get the mass, right? At best an observer could measure the mass from outside, then enter the event horizon and assume that the mass had stayed the approximately the same within certain bounds. Would this be valid?

(To forestall the obvious: the observers would obviously not be human.)

2. Jun 10, 2014

### Simon Bridge

You could, in principle, get a human of free-fall past the event horizon of a super-massive black hole without being torn apart.

You question amounts to what an in-falling observer would be able to see as the singularity is approached.
i.e. as concerns other infalling objects.

Definately not QM.

3. Jun 10, 2014