Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: lunar11 on 03/05/2013 23:50:14
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I once heard on a podcast that if One was falling into a Black Hole and that person looked 'outwards' they would see the entire future of the Universe! Is this true? And if so, then how can this be?
Thanks
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We do not know. Nobody who has been swallowed by a black hole has ever returned to report it [;D]
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I once heard on a podcast that if One was falling into a Black Hole and that person looked 'outwards' they would see the entire future of the Universe! Is this true?
No.
We do not know. Nobody who has been swallowed by a black hole has ever returned to report it
When we respond to questions, in this cae where the answer is "no," what we're always doing is to answer according to what we know of the laws of nature at the time the question has been asked.
If I said that the entropy of a closed system can only increase it means that I'm answering according to what we know of the laws of physics at this time. One of those laws, which is never really explicitly stated, is that the laws of nature don't change with time. So how do I know that the entropy of a closed system can only increase in the future when I haven't tested this law in the future? I answer it according to what we assume that the laws of physics are as we know them today. In this way we can say that a person falling into a black hole does not see the future of the universe.
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Light has a finite speed. Looking outwards you will find incoming light it to blueshift, if standing still relative that Black Hole. Falling in you will, more or less, move with the light, depending on your speed so it shouldn't be as blue shifted as the first case. But at no point will you see the light exceed the speed of light in a vacuum, locally defined. Then again, the universe outside will, as far as I can see, 'accelerate' time wise, relative your local clock. What that will do the light perceived by you I'm not sure of? Because there is nothing stopping the incoming light to reach your eyes, in fact you and it have only one path to go as soon as you crossed the event horizon. Black holes are very strange creatures.
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The way I might imagine it, would be as if you got a 'curtain of light' meeting your eyes as the 'outside' of that event horizon 'accelerates' time wise. That do not mean that light will change a speed for you, what you use measuring a speed will still be your local clock and ruler, 'at rest' with you. But I would guess that it should (time wise) 'compress' all events happening outside the EV, from your (locally defined) point of view, including infalling light? But I'm not sure, it just seems the most likely idea for me at the moment.
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Although if I imagine it from locality? I'm not sure, in that case light becomes a clock 'ticking' at 'c', locally defined by you. So there should be no 'curtain of light' from that scenario, as 'c' still will be 'c'. Which makes it the view I would prefer. The other one becoming contradictory as it can be seen as assuming that you have light 'catching up' to other light, creating that 'curtain'. My own view of it is simpler, as the 'clock', 'c' becomes, is defined locally, and that constant (or arrow) won't ever change for you.
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The point I'm making is that if you assume light to propagate, you also need to assume it to pass time dilations, on its way to you. But that shouldn't change its defined speed (uniform motion) in a vacuum, and it goes for all astronomical light we ever measure. Accelerations and relative motion, as light compared between two objects emitting, may 'compress and elongate' (energy up, or down) the light, as measured locally, depending on direction and 'motion'. But it won't give you a 'curtain of light'.
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Apparently, for charged rotating black holes, there are certain idealized solutions to GR that permit time-like wormholes that would supposedly have the effect of seeing the external universe infinitely speeded up (see Will you see the universe end? (http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/fall_in.html)). However, there is considerable doubt as to whether such a wormhole could actually exist.
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Yes, and maybe that is another reason why singularities are impossible to penetrate (for a far observer). To avoid contradictions in the universe we know.
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Yes. You see the future when you are asleep/dreaming and not blinded by the present. Some dreams are portents. Not everyone is good at it. Some people have perfect recall. Some people have perfect forecall. Future sight is no more strange than memory. We perceive the non present. Take a pen and pad to bed and write down your dreams the instant you wake. Some dreams will be of the past. Some will be of the future.
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Yes. You see the future when you are asleep/dreaming and not blinded by the present. Some dreams are portents. Not everyone is good at it. Some people have perfect recall. Some people have perfect forecall. Future sight is no more strange than memory. We perceive the non present. Take a pen and pad to bed and write down your dreams the instant you wake. Some dreams will be of the past. Some will be of the future.
If you had verifable evidence of this you'd be in for a Nobel... as it is, no.