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black hole (blàk hÖl)
1. An extremely small region of space-time with a gravitational field so intense that nothing can escape, not even light.
2. A great void; an abyss: The government created a bureaucratic black hole that swallows up individual initiative.
Black Hole, theoretical object of extreme density and with a gravitational field so strong that nothing, including electromagnetic radiation, can escape from it. It therefore appears totally black. In 1994 astronomers using the Hubble Space Telescope found the first convincing evidence that a black hole exists. They found that an object of 2.5 billion to 3.5 billion solar masses must be present at the center of the galaxy M87.
The black-hole concept was developed by German astronomer Karl Schwarzschild on the basis of German-American physicist Albert Einstein's theory of general relativity. According to general relativity, gravitation severely modifies space and time near a black hole. Time slows down relative to that of distant observers and inside the black hole stops completely.
Black holes may form from burnt-out stars. As nuclear fuels are exhausted in the core of a star, the pressure associated with their heat no longer resists gravitational contraction of the core. If the core mass exceeds about 1.7 solar masses, collapse to a black hole follows.
English physicist Stephen Hawking has suggested that many black holes may have formed in the early universe. They could compose a significant fraction of the total mass of the universe. Any early black holes weighing less than a few thousand million metric tons will have vanished by now, but heavier ones may remain.
Just like those other black holes from outer space,
Hollywood is postmodern to this extent: it has no center, only a spreading
dead zone of exhaustion, inertia, and brilliant decay.
Arthur Kroker (b. 1945), Marilouise Kroker (birth date unknown), and David Cook (b. 1946), Canadian sociologists. Panic Encyclopedia, "Panic Hollywood" (1989).
"This idea came right away, because of two ideas I was familiar with from my work on quantum gravity The first is that inside a black hole, quantum effects remove the singularity that general relativity says is there - and that we know is there from the theorems of Penrose and Hawking - and a new region of the universe begins to expand as if from a big bang, there inside the black hole.
I remember Bryce Dewitt, who is one of the great pioneers of quantum gravity, telling me about this idea shortly after I began to work for him, on my first postdoc. The second idea - which comes from John A. Wheeler, another great pioneer of the field - is that at such events the properties of the elementary particles and forces might change randomly. All I then needed to make a mechanism for natural selection was to assume that these changes are small, because reading Dawkins taught me the importance for natural selection of incremental change by the accumulation of small changes in the gene. Then, with the universes as animals and the properties of the elementary particles as genes, I had a mechanism by which natural selection would act to produce universes with whatever choices of parameters would lead to the most production of black holes, since a black hole is the means by which a universe reproduces - that is, spawns another. . . .
- Lee Smolin, author of _The Life Of The Cosmos_
Source: New Scientist
January 6, 1999
Add A Few Time-Travelling Tachyons And Black Holes Make Sense DO BLACK holes spit out particles that move faster than light and travel backwards in time? Two physicists in New Jersey say that particles with these bizarre properties could come to the rescue of a promising theory about what happens in the heart of a black hole.The world of very massive objects is ruled by general relativity theory, while quantum mechanics governs the realm of very small scales. Black holes -- enormous stars crushed into no space at all -- fall into both categories, as they are both massive and tiny.Much to the chagrin of physicists, general relativity and quantummechanics appear incompatible, so nobody is sure what equations hold trueat the centre of a black hole. But in the past few decades, a new set of theories has raised the hopes of physicists struggling to understand the interior of these bodies. String theories, for instance, portray black holes and particles as wiggling strings. The disappearance of a particle into a black hole would simply be the result of two different stringsbeing spliced together.
What's even more exciting is that physicists are combining these theories into one large "M-theory", which explains a lot about the interior of black hole. But there is still a flaw: although black holes seem to devour everything that comes their way, this cannot happen under the rules of M-theory. Just as oil and water refuse to mix, so energetic particles cannot merge with black holes, according to the theory. "If you send a particle in towards the black hole, and it gets sufficiently close, it needs some mechanism to be absorbed," says Daniel Kabat, a physicist at the Institute for Advanced Study in Princeton, New Jersey. "Once it gets too close to the black hole, it becomes unstable." Without some way of getting rid of that instability, the black hole would spit out the particle-something that doesn't happen in nature. But now Kabat and Princeton University's Gilad Lifschytz believe they have figured out how to keep M-theory intact, while at the sametime explaining how a black hole can keep down its lunch. The answer lies in tachyons. These are particles with imaginary mass that can be thought of as travelling backwards in time. They move faster than light, and slowing down to the speed of light would be as impossible for them as it is for us to accelerate to light speed. Physicistsalso use the term "tachyon" for a whole family of instabilities that quickly decay.
Though nobody has ever seen one, the researchers have shown that tachyons might get rid of a particle's excess energy, making it palatable to the black hole. In an article due to appear in The Journal of High Energy Physics, they suggest that particles spit out tachyons as they merge with a black hole. "These tachyons wouldbe important for the dynamics inside the black hole, but I don't think an observer outside the black hole would be able to see them," says Kabat.
If tachyons really do solve M-theory's problem, physicists may at last have a way to build up a coherent picture of what happens inside a black hole. "You're able to do precise calculations, and suchcalculations are hard to come by," says Kabat. "It's a pretty compelling picture of a black hole." "This paper is very interesting, and it's potentially important," comments Michael Douglas, a physicist at Rutgers University in New Brunswick, New Jersey. "It poses a lot of ideas."
In 1963, Roy Kerr, a New Zealand mathematician, found a solution of Einstein's equations for a rotating black hole, which had bizarre properties. The black hole would not collapse to a point (as previously thought) but into a spinning ring (of neutrons). The ring would be circulating so rapidly that centrifugal force would keep the ring from collapsing under gravity.The ring, in turn, acts like the Looking Glass of Alice. Anyone walking through the ring would not die, but could pass through the ring into an alternate universe.
Since then, hundreds of other "wormhole" solutions have been found to Einstein's equations. These wormholes connect not only two regions of space (hence the name) but also two regions of time as well. In principle, they can be used as time machines. Recently, attempts to add the quantum theory to gravity (and hence create a "theory of everything") have given us some insight into the paradox problem. In the quantum theory, we can have multiple states of any object. For example, an electron can exist simultaneously in different orbits (a fact which is responsible for giving us thelaws of chemistry). Similarly, Schrodinger's famous cat can exist simultaneously in two possible states: dead and alive. So by going back in time and altering the past, we merely create a paralleluniverse. So we are changing someone ELSE's past by saving, say, Abraham Lincoln from being assassinated at the Ford Theater, but our Lincoln is still dead. In this way, the river of time forks intotwo separate rivers.
- Michio Kaku, Theoretical Physicist
It seems that we know, more precisely than anyone has ever known before, what the Universe is made of, and how much of the different kinds of stuff there are, as well as how the Universe came into existence. We know that it seems to be so efficient at the job of making stars and turning them into black holes that it could almost have been designed for the job. And we know that the ultimate fate of the Universe itself is that one day the present expansion will be first halted and then reversed, so that it collapses back into a singularity that is a mirror-image of the one that gave it birth. We actually live inside a huge black hole - a black hole so big that it contains billions of other black holes inside itself.
Instead of the collapse of a black hole representing a one-way journey to nowhere, many researchers now believe that it is a one-way journey to somewhere - to a new expanding universe in its own set of dimensions. Instead of a black-hole singularity 'bouncing' to become an exploding outpouring of energy blasting back into our Universe, it is shunted sideways in spacetime. The dramatic implication is that many - perhaps all - of the black holes that form in our Universe may be the seeds of new universes. And, of course, our own Universe may have been born in this way out of a black hole in another universe. While the fact that the laws of physics in our Universe seem to be rather precisely 'fine tuned' to encourage the formation of black holes means that they are actually fine tuned for the production of more universes.
- John Gibbon - _In The Beginning: The Birth Of The Living Universe_
If a dying star is too large, gravity overcomes everything. Above a certain critical mass, spacetime becomes bent, escape velocity exceeds the speed of light, and the star simply shuts itself off from the rest of the universe. It becomes a "black hole," one of several hundred million that already punctuate our galaxy, sucking up loose gas and dust like vacuum cleaners whos bags never need changing.
These "tunnels to nowhere" have an inevitably sinister aspect, threatening those who get too close with nonexistence, but it is important to understand that they are inevitable, perhaps even necessary. The same fine-tuning that makes our universe "just right" for life also encourages the production of black holes. John Gribbin, noting that the universe is "so efficient at the job of making stars and turning them into black holes that it could almost have been designed for the job," was the first to suggest that the whole thing might be a black hole itself.
Viewed in this light, if one can talk that way about something that swallows light, black holes graduate from one-way tickets to oblivion to being seeds of new universes. The result of one of an older generation of black holes going about its natural business of reproducing itself. Which suggests that our universe, in its turn, may have been born in just this way, out of a black hole somewhere else. And if the analogy with sexual reproduction is the right one for this process, it is possible that each time a new universe is born it alters the rules slightly, mutating in the way that life does, setting up the possibility of competition between a whole generation of related universes, which opens up the way for natural selection to work amongst them, favoring those most likely to survive and to reproduce again."
- _Dark Nature_ by Lyall Watson
Disney film _The Black Hole_ (vhs/ntsc)
Black Hole, The (1979)
Bob Barbash (story)
Tagline: A journey that begins where everything ends!
Plot Outline: A research vessel finds a missing ship, commanded by a mysterious scientist, on the edge of a black hole.
Cast (in credits order) verified as complete
Maximilian Schell .... Dr. Hans Reinhardt
Anthony Perkins .... Dr. Alex Durant
Robert Forster .... Captain Dan Holland
Joseph Bottoms .... Lieutenant Charles Pizer
Yvette Mimieux .... Dr. Kate McCrae
Ernest Borgnine .... Harry Booth
Tommy McLoughlin .... Captain S.T.A.R
Roddy McDowall (_Planet Of The Apes_) .... V.I.N.CENT (voice)
Slim Pickens .... Bob (voice)
release _Cruel And Unusual_ 7" by Soup on Very Small Records
In the standard theory, acceleration occurs after the big bang because of an ad hoc inflaton field. In the pre-big bang scenario, it occurs before the bang as a natural outcome of the novel symmetries of string theory.
According to the scenario, the pre-bang universe was almost a perfect mirror image of the post-bang one. If the universe is eternal into the future, its contents thinning to a meager gruel, it is also eternal into the past. Infinitely long ago it was nearly empty, filled only with a tenuous, widely dispersed, chaotic gas of radiation and matter. The forces of nature, controlled by the dilaton field, were so feeble that particles in this gas barely interacted.
As time went on, the forces gained in strength and pulled matter together. Randomly, some regions accumulated matter at the expense of their surroundings. Eventually the density in these regions became so high that black holes started to form. Matter inside those regions was then cut off from the outside, breaking up the universe into disconnected pieces.
Inside a black hole, space and time swap roles. The center of the black hole is not a point in space but an instant in time. As the infalling matter approached the center, it reached higher and higher densities. But when the density, temperature and curvature reached the maximum values allowed by string theory, these quantities bounced and started decreasing. The moment of that reversal is what we call a big bang. The interior of one of those black holes became our universe.