Falling into a black hole might not be good for your health, but at least the view would be fine. A new simulation shows what you might see on your way towards the black hole's crushing central singularity. The research could help physicists understand the apparently paradoxical fate of matter and energy in a black hole.
Andrew Hamilton and Gavin Polhemus of the University of Colorado, Boulder, built a computer code based on the equations of Einstein's general theory of relativity, which describes gravity as a distortion of space and time.
They follow the fate of an imaginary observer on an orbit that swoops down into a giant black hole weighing 5 million times the mass of the sun, about the same size as the hole in the centre of our galaxy.
As you approach, a dark circle is bitten out of the galaxy containing the black hole, marking the event horizon – the point beyond which nothing can escape the black hole's grip. Light from stars directly behind the hole is swallowed by the horizon, while light from other stars is merely bent by the black hole's gravity, forming a warped image around the hole.
Horizontal ring
To distant observers, the horizon has a size of one Schwartzschild radius – about 15 million kilometres for this hole – but as you approach, it recedes from you. Even after you cross this radius, there is still a point in front of you where all light is swallowed, so from your point of view, you never reach the horizon.
Hamilton and Polhemus have painted a red grid on the horizon to help visualise it (as the horizon is spherical, the two circles on the grid represent the north and south "poles" of its central black hole). And as you pass one Schwartzschild radius, another artificial visual aid pops up. The white grid that loops around you marks where distant observers would place the horizon – this is where you'd see other people falling in if they followed you through the horizon.
The strangest sight is reserved for your last moments. So close to the centre of the black hole, you feel powerful tidal forces. If you're falling in feet first, gravity at your head is much weaker than at your feet. That would pull a real observer apart, and it also affects the light falling in around you - light from above your head is stretched out and shifted to the red end of the spectrum. Eventually it gets red-shifted into nothingness, so your whole view will be squeezed into a horizontal ring.
Information paradox
This process might shed some light on a black hole puzzle. Quantum calculations seem to show that there is too much complexity within a black hole - in earlier work, the researchers calculated that it should be possible to create much more entropy (a measure of disorder) inside the black hole than is measured by outside observers.
This is like a supercharged version of the old black hole information paradox, which pits the apparent destruction of objects - and information - that falls into a black hole against quantum mechanics, which states that quantum information can never be lost.
The problem may be that we have a naive view of space, which breaks down inside the black hole. To calculate total entropy, Hamilton and Polhemus assumed that you add up all the possible states that matter and energy could take at different points in space. But along with other theorists, they suspect that this usual assumption, called locality, doesn't work inside a black hole. Somehow, different points in space seem to share the same states - but it's not clear how.
That's where visualisations like this might just help. "Close to the singularity, it appears that the entire three-dimensional universe is being crushed into a two-dimensional surface," says Hamilton (see Our world may be a giant hologram). But whether it hints that a 2D view is more fundamental is not yet clear. "Does it have any profound significance? I don't know," says Hamilton.
See also: Three eyes needed to 'see' inside a black hole
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Is There Information Loss ??
Wed Apr 01 23:45:04 BST 2009 by nic
i doubt there is information loss, there is only information not available to us, but still stored there, as blackholes are part of our universe.
In a way empty space is stretched, generated there, like a tube we only cant she the end of it, mater converts to energy (gravity) + empty space.
Its like a dead end road, matter is running to then end of it, but can never get there since the road is stretched, at some point the end is for us out of our sight, but it isnt gone, the road is still there, the information isnt lost.. its still in the road.
Is There Information Loss ??
Thu Apr 02 17:37:52 BST 2009 by Ben
"i doubt there is information loss, there is only information not available to us, but still stored there, as blackholes are part of our universe.
In a way empty space is stretched, generated there, like a tube we only cant she the end of it, mater converts to energy (gravity) + empty space."
The 'Information Loss' *IS* the matter/energy getting pulled in then dissipated as Gravity/Energy.
The problem is matter and energy, getting pulled into a black hole, has information about itself. Once the matter/energy is pulled in to the black hole, it is dissipated back out as information-less gravity. It's like a function that takes in any number but always outputs 1.
Is There Information Loss ??
Fri Apr 03 22:28:54 BST 2009 by Charles
This is one of the big questions. Stephen Hawking recently decided that he'd lost one of his famous bets on this very subject. There is a big problem if information *is* lost in a BH - it would violate unitarity, which is one of the basic tenets of quantum theory. Hence this looks very much like a situation where general relativity breaks down (the fact that the singularity is supposedly infinitely dense is another indicator - it seems unlikely that the real universe contains anything infinitely dense). String theory or some other TOE may explain what's really going on. The Beckenstein bound, Hawking radiation and the holographic priniciple hint that the information content of a BH *may* be stored on the horizon. Perhaps there isn't anything inside, or perhaps there's another universe, or perhaps something completely different...
Meatball, Tidal Forces
Thu Apr 02 00:05:35 BST 2009 by John Mangaovi
I understand the Event Horizon is the circumference beyond which signals cannot escape. But does that mean there are no outward-directed signals at all? I mean, just because they can't escape beyond the Event Horizon doesn't mean they can't approach it at all from the inside. They just can't go beyond it.
So it seems to me that once you cross inward beyond the Event Horizon you might be able to see quite a bit. If an extremely strong object-- say, one of my wife's meatballs-- is falling in along side you, won't light from behind you (also falling in) illuminate the back of the meatball to your eyes?
Meatball, Tidal Forces
Thu Apr 02 05:02:35 BST 2009 by Gavin Polhemus
In the simplest black holes, all light inside the horizon is going toward the singularity. If the black hole is charged or spinning, then it could have a second horizon closer to the singularity (the inner horizon). In side the inner horizon light can go outward again. However, the inner horizon appears to be unstable, so we don't think real black holes have an inner horizon.
Yes, you will be able to see the meatball, in case you want to grab a last meal.
Meatball, Tidal Forces
Wed Apr 08 14:59:00 BST 2009 by Enid
You state: "If the black hole is charged or spinning, then ........"
As no electromagnetic radiation can escape the black hole, what difference does it make if its supposedly charged or not?
Meatball, Tidal Forces
Thu Apr 02 05:09:00 BST 2009 by sauce
I don't know GR, but that black area makes no sense to me either. They must be assuming that this particular black hole has nothing else falling in at the same time, whereas inside a galaxy there would be intense radiation in all directions as falling particles collide.
Would there be a level that is visible because gravity was ripping apart the vacuum and creating Hawking radiation?
Meatball, Tidal Forces
Thu Apr 02 06:30:32 BST 2009 by Gavin Polhemus
You are right, this simulation does not have anything falling into the black hole. Adding matter requires a great deal of computing power. Andrew has done some of this for the National Geographic channel, but those are not up on his website.
You can't see the level where the Hawking radiation is being produced because the Hawking radiation is very long wavelength radio waves. The wavelengths are about the same size as the black hole.
Meatball, Tidal Forces
Tue Feb 09 21:57:13 GMT 2010 by blah
Only if the meatball was further away from the sigularity than you were. Then you would see 2 meatballs, one from the past and one from the future.
Lines Of Information
Thu Apr 02 00:39:44 BST 2009 by Neal Hanson
Also a mystery (to me), is how black holes can generate red lines across its "surface".
Lines Of Information
Thu Apr 02 02:38:42 BST 2009 by malcoda
Much is a mystery to those who don't read...as in the article. The red lines and the white grid are visual markers added in to help understand more clearly what is being seen.
Lines Of Information
Thu Apr 02 13:41:58 BST 2009 by Doug
Ah, the joys of sarcasm misunderstood. What I'd like to know (please forgive the snarkiness) is whether Sandrine sounds like that in real life. She comes off as a touch robotic in these video segments, and I'm trying to imagine her telling a joke. Still and all, I wish I had her job.
Lines Of Information
Fri Apr 03 00:50:06 BST 2009 by Brian Yerk
Amazing how much of a jackass some "brainy" people can be. Perhaps you should have stated, "Much is a mystery to those without social skills"....
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