what,exactly,is an Event Horizon and in what context is the term used?
474017
An event horizon is the theoretical visible edge of a black hole.  A black hole is a mass so dense that its gravity will allow nothing to escape, not even an object travelling at the speed of light, not even light itself.  An event horizon is the boundary of a black hole at which light can still escape.  Therefore we could see everything that happens up to an event horizon, in theory.  Beyond this boundary, light is drawn back into the super-dense mass and nothing can be seen.
224610
unless this is a "zen" question, it doesn't "go" anywhere.  A black hole is a former star that has died and collapsed in upon itself and had its mass "infinitely" compressed into a tiny tiny volume.
178554
goes in the black hole ->O.\nonce past the point of Singularity which is believe to be much smaller than an atom's nucleus. then past the event horizon where time becomes irrelevant. and if that something is still in 1 piece, then it should come out to the white hole O->.
1035592
You're question is worded strangely.\n\nModern physics suggest that time does not, as we commonly percieve it to, progress steadily forward from one moment to another. The reason is that there is no plausable mechanism to show how one "moment" is suddenly lit up and set aside as being "now". Furthermore, special relativity shows us that two different observers who are moving relative to one another would disagree about what events constitute a "now". \n\nSo the idea of stopping something that isn't moving in the first place is rather presumptuous.\n\nHowever, throwing caution to the wind, there is every reson to believe that time stops for a weightless particle moving at the speed of light, and that time stops within the event horizon of a black hole. For whatever those observations are worth... there they are.\n\nHope that helps.\n\nEdit - S_k_Latif, please either more thoroughly research and understand the topics you reply to, or do not reply to them at all. There is no good reason to spread faulty or innacurate information. What you just said makes exactly zero sense. Just being honset.
790112
A black hole is an object predicted by general relativity with a gravitational field so strong that nothing can escape it — not even light.\n\nA black hole is defined to be a region of space-time where escape to the outside universe is impossible. The boundary of this region is a surface called the event horizon. This surface is not physical, just an imaginary boundary. Nothing can move from inside the event horizon to the outside, even briefly.\n\nThe existence of black holes in the universe is well supported by astronomical observation, particularly from studying X-ray emission from X-ray binaries and active galactic nuclei. It has also been hypothesized that black holes radiate energy due to quantum mechanical effects known as Hawking radiation. \n\nHistory\n\nThe concept of a body so massive that even light could not escape was put forward by the English geologist John Michell in a 1784 paper sent to the Royal Society. At that time, the Newtonian theory of gravity and the concept of escape velocity were well known. Michell computed that a body with 500 times the radius of the Sun and of the same density would have, at its surface, an escape velocity equal to the speed of light, and therefore would be invisible. In his words:
661081
A black hole is a concentration of mass great enough that the force of gravity prevents anything past its event horizon from escaping it except through quantum tunnelling behaviour (known as Hawking Radiation). The gravitational field is so strong that the escape velocity past its event horizon exceeds the speed of light. This implies that nothing, not even light, inside the event horizon can escape its gravity. It is, however, theorized that wormholes can provide an exit path for energy or matter. The term "black hole" is widespread, even though it does not refer to a hole in the usual sense, but rather a region of space from which nothing can return.
841834
Natures answer to the Dyson vacuum cleaner, when the event horizon from 3 or more black holes collide, the combined mass is so great it will start to pull in all matter, all energy, and all time. When enough matter is in one place it becomes unstable, and threes a big bang, and the universe and time starts again!
731883
A black hole is a star which has loss most of its mass but retains enough gravity to trap everything including light\n\nA quantum Singularity is close to the same definition of a black hole but it is a point in space that can contain unlimited amounts of mass or things\n\nA wormhole is an unsteady disturbance in the space time continuum that allows for easy journey between two points in space within a reasonable time. Wormholes are sometimes believed to be on the other side of black holes often called white holes for the fact that if they were on the other side of black holes that constantly capture light it would be radiating from the other side
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.
580033
You've probably seen the pictures of a grid with a giant funnel extending infinitely downward.  That's not the shape of the hole itself, but a map of the curvature of space near the singularity.  The singularity, or "hole" itself is a point of infinitely large density and infinitely small size.
418005
First a black hole is a point of infinite density where gravity is so strong that even light cannot escape. A white hole is a hypothetical point of negative gravitational energy that emits matter from it. By negative gravitational energy i mean this: A planet has positive gravitational energy because it pulls matter towards its center of mass and experiences normal everyday gravity, but a white hole, which has negative gravitational energy is the exact opposite, it repels matter and nothing, not even light can reach the surface of a white hole. A wormhole is a hypothetical shortcut in the fabric of space and time. Think of it like a blanket that you are trying to get across, the simplest way to cross it is to just follow its surface in a straight line. A worm hole on the other hane is like folding the blanket in half and cutting a hole in it and going through that hole which is a much much shorter and quicker way of moving long distances.
326157
I have a feeling you mean "when" not where?\n\nThe concept of a body so massive that not even light could escape it was put forward by the English geologist John Michell in a 1783 paper sent to the Royal Society.\n\nBefore the term black hole was created (i believe in the late 60's) reference to this kind of object was called a black star in the origional 60's star trek series.
1063220
A warp cushion, the space of where a worm hole used to be leaves a different time around it and inside it.\nThe bubble like on Lost in Space is possible. Time holds space not Space holds Time otherwise we wouldn't be here now.
997242
It would be the speed of light at the event horizon, which is defined as the point at which escape velocity is the speed of light. Escape velocity is basically defined as the speed of something that fell from rest at infinite distance. The diameter of the event horizon is also often considered as the diameter of the black hold. What happens inside the event horizon really esoteric, and way beyond my knowledge anyway.
505040
Stephen Hawking hypothesized that black holes lose energy (and thus mass) due to the formation of particle-antiparticle pairs on event horizon, where one particle is ripped from its partner into the hole while the other is boosted away. But this violates conservation of energy, as the particle that escaped has virtually come from nothing. Somehow, the black hole emits radiation to equal this missing energy (this is Hawking's paper). Thus, according to this theory, black holes slowly evaporate over time.\nThere are a few problems with this theory, though. See
32519
A Yahoo Search for black holes turns up a bunch of useful sites:\n\nhttp://search.yahoo.com/search?p=black+holes&y=Search+the+Web&ei=UTF-8&fr=sbc-web&x=wrt\n\nThe Wikipedia article is a good start:\n\nhttp://en.wikipedia.org/wiki/Black_hole\n\nAnother really good starting place is Stephen Hawking's new book "A Briefer History of Time".  Which is an update to his previous book "A Brief History of Time"\n\nhttp://shopping.yahoo.com/search?fr=ytff1-&p=A+briefer+history+of+time&ei=UTF-8&cop=mss
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