A question about the information paradox - black holes?
603265
The answers you got were good and should help you understand the idea, but to specifically answer your question, the 'information' in the information paradox is just the particular pattern of stuff inherent in the matter falling into the black hole:  The particular way the atoms are arranged, the speed they're moving, their direction, etc.  All these things are specific to the individual atoms falling into the black hole and are wiped away once it falls through the event horizon of such a hole.  This doesn't mean anybody's sending notes back and forth encrypted it chunks of stuff, in this case 'information'='pattern', and that's all, nothing more.\n\nP.S. HawkinG, not HawkinS
847821
Once you cross the event horizon of a black hole there is no going back. You have essentially crossed into a different universe... or a part of this universe that is permanently cut off from the rest of it. \n\nBut, crossing the event horizon is not quite the end of your journey - in a large enough black hole you can cross this boundry without doing any harm to yourself, and it can still take millions (or more) years before you reach the black hole - the only problem is that you can never stay still, and you will always be getting closer to the centre. You can also never send signals back outside the hole (because light is also dragged towards the middle of the hole.)\n\nBut what's in the centre? The answer is 'a singularity.' This is a point where spacetime has infinite curvature. Still no help? Well... it's hard to describe, because we don't have a good enough theory of quantum gravity - quantum theory breaks down when things become very big, and gravitatinoal theories (ie relativity) breaks down when things become very small. A singularity is a lot of mass squashed up into a minute volume - so neither of our two best theories of the universe are much help.\n\nBut... if you want a mental image of a singularity, think of an awful lot of stuff squashed up so small and so dense that it rips a hhole in our universe.
697469
it can be. Because blackhole has a much faster velocity than light. It is possible that we can use blackhole to travel into another galaxy or another space that we haven't know before. Or maybe we can use blackhole as a time machine. Everything can happen, one day we can find it out. I believe that
383398
Not much actually as we still don't really have a clue what black holes actually are.\nThere are many questions to ask about the greenness of the black hole.. First, if the light is coming from the black hole itself then we actually don't have any black holes and everything we thought about them was wrong. \nScience is the art of guesswork based on what we already know. The term for this is called EMPIRICAL Science. Basically everything we are aware of is explained in this way.. When we make new laws or decided a black hole is a black hole, we are only guessing according to what we already know. \nIf you remember, people thought the world was flat, based on what they knew at that time. \nAnd the zeroth law of thermodynamics is called the zeroth because they had already come up with the first ,second and third before they realised they'd missed one..\nThe good thing about this is that essentially, this makes you just as smart as any of the top scientists in the world. Sadly, most of them would not share this point of view!!!!!
55587
By definition, something which cannot be detected does not exist (note: something that potentially COULD be detected, but hasn't been DOES exist; it just hasn't been detected).  For example, there can be large technological metropolis filled with aliens on a planet just inside of a black hole, but because we can never observe information from the hole, we say the city doesn't exist.  Same with the 'outside' of the universe.  If information can never enter the universe, than anything outside of the universe doesn't exist.  Such objects, the black hole city and the 'outside' of the universe, fall within the realm of metascience or philosophy.  However, just as we cannot prove they exist, we likewise cannot collect sufficient information to say that they don't, and it is this inability to test that makes it philosophy, not science.  PS: The black hole 'city' example was ridiculous, but it was more poetic than saying 'quantum particle' ;)
57542
Scientists think that, at some point in the very distant future, all of the mass in the universe will be dominated by four or five supermassive black holes.  At first glance, this doesn't square with the second law of thermodynamics (since that's a rather low entropy state), so someone postulated that there would be such a thing as a lighthole which would re-emit everything that fell into a black hole.\n\nThat was utter nonsense.\n\nStephen Hawking put his brain to work on this problem, and solved it in a day.  He realized that, as predicted by Einstein's famous equation, gravitational fields can spontaneously create pairs of particles (one being normal matter, and the other being anti-matter).  Under normal circumstances, the matter-anti-matter pair would annihilate, but if the pair forms on the event horizon of a black hole, one of the particles would be drawn into the black hole, while the other would be emitted into space.  By doing this, the black hole has expended some of its gravity, and therefore its mass.\n\nThe answer to the conundrum is that Black Holes are slowly evaporating through this process, and we've named it the Hawking radiation, accordingly.  If the Universe is ever dominated by a handful of supermassive black holes, that won't violate the Second Law of thermodynamics since they're slowly falling apart anyhow.\n\nThere is no need for a white hole to exist, nor is there any observational evidence even suggesting that they might.
401374
According to Stephen Hawking, pretty much the guy to ask, even black holes do, by a certain mechanism, radiate very small amounts of energy over time.  So in the space of many, many eons it could eventually 'evaporate'.  It would take a ridiculously long time to happen, though.\n\nA pal of mine who was in first year science with me is now a worldwide expert on black holes, the big bang, and simulating them.  He actually won a bet with Stephen Hawking (a T-shirt - I'd frame it).
230892
...a black hole is it is not really a hole...you should be able to go behind it, in front of it, and so on...for example leading scientist know think that the center of our galaxy is a black hole...now you can see that there is something on the otherside of it...the galaxy is not cut in half with us only waiting for our end...it is simply a piont in space in with nothing can escape (check first reference)\n\nthe word "black hole" was coined by scienctist john wheeller (sorce #2)...it was basically science shorthand...then hollywood got a hold of the name and behold...people now think there is someting on the other side...some magical land were unicorns and wizards breath\n\na black hole is what left after a star at least 10x the size of our sun uses all the energy ...after which the star goes super nova, then it becames a black hole (#3)...\n\nlong story made short...what is behind a black hole...most likely another star...then another...then another\n\nwhat would happen if  you tried to go trough a black hole...you would be crushed and then you would die
929295
It wasn't Hawking who came up with the theory, but at the core of a black hole is a body of super dense matter wherein even the space between the nucleus  of an atom and its electrons has been compressed into nothingness.\n\nImagine all the matter that composes a large cruise ship occupying a space less than the size of a tear-drop.\n\nAll still theory, though the evidence has gotten pretty convincing over the last 60 years.
1117575
It is precisely that the density of a black hole is beyond the scope of reality that makes a black hole what it is - a singularity. In mathematics, a singularity is a point at which an equation cannot be solved. A simple example is 1/x, which is undefined at 0. In a black hole, the laws of physics have no solution.\n\nThe atomic bomb has nothing to do with this. Radioactive material like plutonium will explode in a runaway chain reaction if sufficient mass is brought together. (An explosive mass of radioactive material is called a prompt critical mass.) This only works with highly radioactive materials and involves no compression, whereas anything will form a black hole if sufficiently compressed. Compressing matter to this level is far beyond our current capabilities, however; it takes the collapse of a massive star to make a black hole.
571912
Good, very good!!\nJaxon is very right.\n\nAdd few things:\n\n1. Black holes are the least understood entities and by nature human beings perfer to know about unknown.\n\n2. Neutron stars and black holes are closely related, they differ in amount of gravitational pull.However neutrn stars are visible and so are being reffered as a paddestal to understand black holes.\n\n3. As jaxon pointed out black hole may indicate end of univers: be clear, end of universe in terms of time not boundries or limits.\n\n4. Generally Black holes are present in the centre of glaxies so they help in understanding the creation of glaxies.\n\n5. As referred by jaxson about light: Be clear that the gravitational pull of black holes is so great that light can not escape out of a black hole.\n\n6. The postulate in the theory of relativity regarding deflection of light path under the influence of greavity is is witness near Neutron stars and black holes.
1095953
There are no black holes close enough for a terrestrial probe to reach them yet. According to current theory, the intense gravitational field would trap any electromagnetic signal the probe might be sending out after it crossed the event horizon, so we wouldn't know what happened in any event.
486631
Assuming this is possible the end positioned inside the event horizon would be broken down into it's individual atoms and would cease to exist.  However some scientists (me being one of them) think black holes are only one end of a worm hole and that when you reach the event horizon you are expelled out of a white hole into another universe.  Think of a white hole as the polar opposite of a black hole, instead of consuming every thing it expels everything
1166146
Yes........more or less. A Black hole is a small view of what the universe as a whole will be like billions of years from now.
1158120
Wow.\n\nA few people here know what they're talking about.  A few.  Very few.\n\nMost of these responses are absolutely hilarious.  Most of them are from people trying to sound smart, in which case they do NOT.  Other cases are from kids with big imaginations, with "Anything is possible!"\n\nEinstein was brilliant, no question.  But all great scientists are capable of mistakes, and Einstein was no exception.\n\nHis theory on time travel was based on the speed of light and the "paradox" in which light travels at a fixed rate of speed.  This is true; light moves at 186,000 mps no matter what conditions are in place.\n\nHis theory's flaw is accounted to the fact that light has NO mass.  Light, in it's fixed movement, cannot be compared to any living organism (which is made up of mass) or any other object.  Any object made up of mass (for example, a human being, or any kind of lightspeed-capable rocket ship) does NOT have a fixed speed; therefore the velocity equation paradox that Einstein based his theory on does not apply to them.\n\nThis is all I want to say tonight.  Anyone who understands his theories will understand what I've said here, so think about my statements.  Let me know what you think (again, only those of you who understand what Einstein's theories were all about), as I'm no expert on relativity.  Like everyone else posting on a Yahoo answers forum about Albert Einstein and his theories on time travel, I'm just a fan.  Don't act like any of us are any more.\nEveryone else:  Please don't worry about it.\n\nAlthough I am skeptical by nature, like any smart person, it is NOT my goal to bash the idea of time travel.  After I spotted the flaw in Einstein's theory I presented it to many professionals in the field (or the few that I know, anyway) and have so far received very positive feedback.  I searched online as well and have discovered that others seem to have come up with the same idea, or similar.  Let me know what you think about the whole deal.\n\nBeing proven wrong only makes you smarter.
352119
The black hole information paradox results from the combination of quantum mechanics and general relativity. It was a contentious subject for science since it violated a commonly assumed tenet of science - that information cannot be destroyed. See Liouville's theorem (Hamiltonian) and unitary transformation.\n\nIn 1975, Stephen Hawking and Jacob Bekenstein showed that black holes should slowly radiate away energy, which poses a problem. From the no hair theorem one would expect the Hawking radiation to be completely independent of the material entering the black hole. However, if the material entering the black hole were a pure quantum state, the transformation of that state into the mixed state of Hawking radiation would destroy information about the original quantum state. This violates Liouville's theorem and presents a physical paradox.\n\nMore precisely, if we have an entangled pure state and we throw in one part of the entangled system into the black hole while keeping the other part outside, we get a mixed state after we take the partial trace over the interior of the black hole. But since everything within the interior of the black hole will hit the singularity within a fixed finite time, the part which is traced over partially might "disappear", never to appear again. Of course, we don't really know what goes on at singularities once quantum effects are taken into account, which is why this is conjectural and controversial.\n\nHawking was convinced however because of the simple elegance of the resulting equation which 'unified' Thermodynamics, Relativity, Gravity and Hawking's own work on the Big Bang. This annoyed many physicists, notably John Preskill, who in 1997 bet Hawking and Kip Thorne that information was not lost in black holes.\n\nThere are various ideas about how the paradox is solved. Since the 1998 discovery of the AdS/CFT correspondence, the predominant belief among physicists is that information is preserved and that Hawking radiation is not precisely thermal but receives quantum corrections. Other possibilities include the information being contained in a Planckian remnant left over at the end of Hawking radiation or a modification of the laws of quantum mechanics to allow for non-unitary time evolution.\n\nIn July 2004 Stephen Hawking announced a theory that quantum perturbations of the event horizon could allow information to escape from a black hole, which would resolve the information paradox. Basically, his argument assumes the AdS/CFT correspondence which states that an AdS black hole is dual to a thermal conformal field theory, which is unitary. However, as of 2004 the full details of the theory have yet to be published, so most peers are reserving judgment before accepting the result. When announcing his result, Hawking also conceded the 1997 bet, paying Preskill with a baseball encyclopedia (ISBN 189496327X) 'from which information can be retrieved at will'. Thorne, however, remains unconvinced of Hawking's proof and declined to contribute to the award.\n\n\n[edit]\n\nThe Equation\n\nEntropy of a black hole.\n\n\nS = &#92;frac{c^{3}A}{4 &#92;hbar G}\n\n\nS = entropy, c = speed of light, A = surface area, ħ ("h-bar") is the reduced Planck's Constant (or Dirac's Constant), G = constant of gravitation.
144870
We have no idea what happens to any matter inside a black hole. The laws of physics that we know do not apply.