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Q & A: are black holes hollow shells?

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Most recent answer: 04/09/2015
Q:
Are black holes really hollow shells of matter? My question arises from trying to understand the time dilation effects at the event horizon. For an outside observer watching an star/spaceship/neutron fall into a black hole, wouldn't that star/spaceship/neutron appear to slow down the closer it got to the event horizon (ignoring the fact that "watching" photons coming from the star/spaceship/neutron would be eventually be so red-shifted as to be unobservable)? In other words, whatever is falling into the black hole never actually reaches the event horizon (from the perspective of an outside observer) as it would require an infinite amount of time (from the outside observer's viewpoint). Hence, from the viewpoint of an observer outside the event horizon, matter never actually gets past the event horizon and just builds up as a dense shell of matter.
- Tony (age 46)
Sydney, NSW, Australia
A:

Yes, your description is the current picture of black holes, as seen from far outside. There's very little practical difference between the behavior  this hollow-shell and a fully formed black hole. Either one ultimately should evaporate via Hawking-like radiation.

Mike W.


(published on 04/09/2015)

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