What would you see from inside a black hole?
We know that black holes suck in light. So if you were inside a black hole, would it seem incredibly bright, or is the light destroyed/converted somehow as you fall into the black hole? Also, can you see out? The videos we looked at seemed to show that everything turns into a doughtnut shape around you?
We are - Sam, aged eight and mummy aged 37, high school science teacher!!
This is a really interesting question and I have taken some time to think about my answer so I hope that I will get it at least mostly right. Black holes are strange things - completely outside of our normal physical intuition so it can be really hard to think about what things would be like near them! Of course the first thing that I should say is that it would not be possible to go into a black hole and survive long enough to look out. If you were not torn apart by the enourmous tidal forces you would be fried by the extremely high energy radiation (X-rays and Gamma-rays) 'raining' down on you. Also between crossing the event horizon and hitting the central singularity is likely to be only a fraction of a second of your time!
That being said, it is interesting to think about what things would look like if we could see them. The first thing that comes to mind is that as the light from the universe "falls" into the black hole it gains energy. This means that its wavelength gets shorter. Blue light has a shorter wavelength than red light - so very simply things would appear to get bluer. There is also light outside the range which we can see (as I'm sure Mummy knows, see also this nice explanation with diagrams ) so the longer wavelength radiation would get shifted into the visible range (and through it) and the visible would get shifted to shorter wavelengths. Eventually at the event horizon there is an infinite shift - so the light has an infinite amount of energy, but zero wavelength. What this would look like I can't even imagine! I'm not sure if you could see it even if you hadn't been killed by the gamma-radiation hitting you as you got close to it!
Now if we assume not only that we haven't died on the way into the black hole, and that we can see the light which has an infinite blue shift we would be able to see some weird things. If we looked away from the singularity at the centre of the black hole we would be able to see the whole universe in one small patch of our sky - even the stuff that is actually behind the singularity! Also time outside would appear to be running much faster, so we would be able to see the evolution of the universe "flash" before our eyes.
It would be pretty interesting I think - although like I said it would seem to be completely impossible to even do and certainly impossible to survive it given that you would then be stuck inside a black hole!
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