Measurement of singularity as a particle inside event horizon

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SUMMARY

The discussion centers on the measurement of a singularity treated as a particle inside the event horizon of a black hole. It highlights the impossibility of direct measurement using photons due to the nature of event horizons, while suggesting that indirect measurements through the behavior of surrounding particles may be feasible. The implications for the uncertainty principle are examined, questioning whether a singularity's position can be known without affecting momentum measurements. The conversation concludes that while mass can be known from outside the event horizon, an observer inside cannot measure the event horizon's size directly.

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  • Understanding of general relativity concepts, particularly black holes and event horizons.
  • Familiarity with quantum mechanics, specifically the uncertainty principle.
  • Knowledge of particle physics and measurement techniques in quantum systems.
  • Basic grasp of astrophysics related to singularities and their properties.
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nomadreid
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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.)
 
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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.

definitely not QM.
 
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Thanks, Simon Bridge.
Oops, I forget how to move this thread to a more appropriate topic (General Relativity): it's not in "Thread tools", and this does not seem to be covered in "Help". I don't find any other relevant buttons to click. Help?
 

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