Black Holes |
Black Holes |
Dec 7 2005, 04:04 PM
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#1
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Newbie Group: Members Posts: 8 Joined: 6-December 05 Member No.: 599 |
any one wanna talk black holes. i'm not a professional or anything. i vaguely remember hearing s. hawkin revising his opinion on it saying it wasnt a "worm hole" anymore and that it just destroys all matter and worth nothing else.
i only make my observations, childlike actually, to that of what happens on earth, and why shouldnt it happen in the rest of the universe. why should anything here (goverening law of physics, etc.) be different anywhere else? just like a tornado, or water running down a drain (or that infamous lake that was drained by accident by some guys drilling and all the water drained into the salt mine, i cant remember the name now but a 6 inch hole sucked in a tanker), why wouldnt a black hole be that "event" that punched a hole into another "dimension/galaxy whatever" with less pressure. and maybe all that "dark matter" is the "reminant" of what comes out of a black hole. i dont know, just talking. my head is always "out there, out of earth..." maryalien |
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Dec 8 2005, 01:52 PM
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#2
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
Mind? Of course not! That's what we do here.
By the way, I did a bit of research and got an explanation for the evaporation of black holes. It seems that there is a phenomenon known to exist in the cosmos called "vacuum fluctuations." Basically, what happens is that a pair of particles -- basically, a particle and an anti-particle, or in other words, matter and anti-matter -- can appear spontaneously in a vacuum. They immediately annihilate each other, so conservation of mass and energy is maintained. But for that instant, it is not. And it is that violation of the second law of thermodynamics that allows a black hole to evaporate. You see, over the course of billions of billions of years, such a pair of particles will appear billions of times next to the event horizon of a black hole. One of the pair will be swallowed by the black hole, and the other will radiate away from the black hole. The effect is such that the mass of the particle that escapes is actually reduced from the mass of the black hole. Over billions of billions of years, this process will reduce the mass of a black hole down to zero. But, as Richard says, that process takes many, many times longer than the cosmos has already existed. So, a vast majority of black holes haven't lost all that much mass, and it will take many billions of times longer than the Universe has already existed for most black holes to evaporate in this fashion. And since there is little data to constrain the upper or lower limits of the spontaneous particle creation/annihilation, it's hard to set an exact date by which all the black holes in the Universe will evaporate. So -- in the final analysis, it's something that happens. But it happens so slowly, relatively speaking, that we don't have to worry too much about it. -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Dec 8 2005, 02:30 PM
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#3
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Member Group: Members Posts: 290 Joined: 26-March 04 From: Edam, The Netherlands Member No.: 65 |
QUOTE (dvandorn @ Dec 8 2005, 01:52 PM) But, as Richard says, that process takes many, many times longer than the cosmos has already existed. So, a vast majority of black holes haven't lost all that much mass, and it will take many billions of times longer than the Universe has already existed for most black holes to evaporate in this fashion. And since there is little data to constrain the upper or lower limits of the spontaneous particle creation/annihilation, it's hard to set an exact date by which all the black holes in the Universe will evaporate. So -- in the final analysis, it's something that happens. But it happens so slowly, relatively speaking, that we don't have to worry too much about it. -the other Doug As far as i know, singularities can exist in a variety of "sizes" and the time it takes for a black hole to evaporate by means of "Hawkins radiation (particles, antiparticles and gamma radiation) depends on it's mass. The lighter a black hole is, the faster it evaporates. Black holes that reside in galaxies (the 1 billion solar mass ones) theoretically take 10 to the 73 years to evaporate. However, there's theoretical evidence that smaller black holes (even as tiny as the Planck length) exist as well and they evaporate in very short times (instantly that is). A question that keeps me curious about this theory is: if there's radiation coming from a black hole in the form of particles, antiparticles and gamma radiation (which has a speed of 300000 kms/hour), there must be other forms of radiation (the long searched gravity waves that is thought to escape from neutronstar-pairs ?) that can make its way from the event horizon. Why should gamma radiation make it, while other wavelengths cannot ? Great explanation "other Doug' ! |
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Dec 10 2005, 01:18 PM
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#4
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Newbie Group: Members Posts: 8 Joined: 6-December 05 Member No.: 599 |
QUOTE (Marcel @ Dec 8 2005, 02:30 PM) As far as i know, singularities can exist in a variety of "sizes" and the time it takes for a black hole to evaporate by means of "Hawkins radiation (particles, antiparticles and gamma radiation) depends on it's mass. The lighter a black hole is, the faster it evaporates. Black holes that reside in galaxies (the 1 billion solar mass ones) theoretically take 10 to the 73 years to evaporate. However, there's theoretical evidence that smaller black holes (even as tiny as the Planck length) exist as well and they evaporate in very short times (instantly that is). A question that keeps me curious about this theory is: if there's radiation coming from a black hole in the form of particles, antiparticles and gamma radiation (which has a speed of 300000 kms/hour), there must be other forms of radiation (the long searched gravity waves that is thought to escape from neutronstar-pairs ?) that can make its way from the event horizon. Why should gamma radiation make it, while other wavelengths cannot ? Great explanation "other Doug' ! wasnt there a nasa presentation about GRB's and solving their mystery? i saw it in another forum but couldnt find an update as of yet. does this tie in? mar |
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Dec 12 2005, 03:54 PM
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#5
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Paper: astro-ph/0512241
Date: Fri, 9 Dec 2005 06:09:19 GMT (23kb) Title: Capture of a Red Giant by the Black Hole Sgr A* as a Possible Origin for the TeV Gamma-Rays from the Galactic Center Authors: Y. Lu, K.S. Cheng & Y.F. Huang Comments: 15 pages, 1 figure, Accepted to ApJ \\ Non-thermal TeV $\gamma$-ray emission within multi-pc scale has been observed from the center region of our galaxy. We argue that these $\gamma$-rays are the result of a transient activity of the massive black hole Sgr A$^*$ which resides at the Galactic center. About thousands of years ago, the black hole may have experienced an active phase by capturing a red giant star and forming an accretion disk, temporarily behaving like an active galactic nuclear. A powerful jet, which contains plenty of high speed protons, was launched during the process. These runaway protons interact with the dense ambient medium, producing TeV $\gamma$-ray emission through the $\pi^\circ$-decay process. We show that the total energy deposited in this way is large enough to account for observations. The diffusion length of protons is also consistent with the observed size of the TeV source. \\ ( http://arXiv.org/abs/astro-ph/0512241 , 23kb) -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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