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When a particle crosses the event horizon of a black hole, at one short moment in time would it appear for that particle as if it was surrounded by a black hole?

Regardless of which direction you look, from that particle, you would look towards the center of that black hole?

It would be impossible to determine, for that particle - from which direction the gravity was pulling.

This leads to the following question, which some seem to think is absurd:

Could the expansion of the observable universe, in fact be spaghettification of the observable universe?

Spaghettification sounds like a very one-dimensional effect, which fits poorly with uniform expansion in every direction - but I have a feeling that also this could be explained - either by introducing more dimensions or - even more absurdly, placing the particle closer to the center of the black hole.

Qmechanic
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frodeborli
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1 Answers1

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No, an infalling observer would not see what you describe.

It turns out that an observer falling towards the black hole sees an apparent horizon that retreats before them, and in fact they never cross the horizon. The distance to the apparent horizon measured by the falling observer decreases as the observer falls towards the singularity, but only becomes zero at the singularity.

This is explored in the question Taking selfies while falling, would you be able to notice a horizon before hitting a singularity? and you might find that interesting reading. Also relevant are Would the inside of a black hole be like a giant mirror? and Does someone falling into a black hole see the end of the universe?.

Googling will find you various web sites with calculations of what an infalling observer would see. The JILA site is one of my favourites. There is visual distortion, but nothing like you describe.

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John Rennie
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