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Black holes evaporating?
Brian Cox on his prog last night twice mentioned this, as near enough the
last throes of the dying universe - how does a black hole "evaporate"? ad: Talks in Southampton on scientific topics http://www.divdev.fsnet.co.uk/scicaf.htm |
#2
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Black holes evaporating?
On 07/03/2011 08:22, N_Cook wrote:
Brian Cox on his prog last night twice mentioned this, as near enough the last throes of the dying universe - how does a black hole "evaporate"? Hawking radiation - virtual particle anti-particle pairs occur as fluctuations in the pure vacuum. If one falls in and the other escapes to infinity then the black hole loses mass-energy in the process. Casimir effect is related and observed in lab experiments. http://en.wikipedia.org/wiki/Casimir_effect It is amazing how early on this was measured! Slightly less handwaving version online at: http://casa.colorado.edu/~ajsh/hawk.html http://en.wikipedia.org/wiki/Hawking_radiation The lower the BH mass the higher its effective radiation temperature which means that the final signature of a BH going pop is expected to be quite violent. Big ones take almost forever to evaporate but are expected to do so eventually almost everything is gone by 10^150 years. If the existence of Hawking radiation is ever confirmed observationally or experimentally in nano black holes made by particle physics in the LHC then Hawking will be given a Nobel prize. Most physicists think his model is correct, but the Nobel committee requires experimental verification. A restriction that they don't seem to place on the Economics prize! Regards, Martin Brown |
#3
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Black holes evaporating?
Martin Brown wrote in message
... On 07/03/2011 08:22, N_Cook wrote: Brian Cox on his prog last night twice mentioned this, as near enough the last throes of the dying universe - how does a black hole "evaporate"? Hawking radiation - virtual particle anti-particle pairs occur as fluctuations in the pure vacuum. If one falls in and the other escapes to infinity then the black hole loses mass-energy in the process. Casimir effect is related and observed in lab experiments. http://en.wikipedia.org/wiki/Casimir_effect It is amazing how early on this was measured! Slightly less handwaving version online at: http://casa.colorado.edu/~ajsh/hawk.html http://en.wikipedia.org/wiki/Hawking_radiation The lower the BH mass the higher its effective radiation temperature which means that the final signature of a BH going pop is expected to be quite violent. Big ones take almost forever to evaporate but are expected to do so eventually almost everything is gone by 10^150 years. If the existence of Hawking radiation is ever confirmed observationally or experimentally in nano black holes made by particle physics in the LHC then Hawking will be given a Nobel prize. Most physicists think his model is correct, but the Nobel committee requires experimental verification. A restriction that they don't seem to place on the Economics prize! Regards, Martin Brown I thought a definition of a black hole was that neither mass nor energy could ever leave, so I must forget that "definition" I liked his falling cup and falling laser beam extension of the falling feather and lead weight under gravity , if earth was big enough to observe both , on last night's Sky at Night Somehow over the decades I'd never some across his first item, the Chankillo calendar http://hila.webcentre.ca/projects/chankillo |
#4
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Black holes evaporating?
On 07/03/2011 10:41, N_Cook wrote:
Martin wrote in message ... On 07/03/2011 08:22, N_Cook wrote: Brian Cox on his prog last night twice mentioned this, as near enough the last throes of the dying universe - how does a black hole "evaporate"? Hawking radiation - virtual particle anti-particle pairs occur as fluctuations in the pure vacuum. If one falls in and the other escapes to infinity then the black hole loses mass-energy in the process. Casimir effect is related and observed in lab experiments. http://en.wikipedia.org/wiki/Casimir_effect It is amazing how early on this was measured! Slightly less handwaving version online at: http://casa.colorado.edu/~ajsh/hawk.html http://en.wikipedia.org/wiki/Hawking_radiation The lower the BH mass the higher its effective radiation temperature which means that the final signature of a BH going pop is expected to be quite violent. Big ones take almost forever to evaporate but are expected to do so eventually almost everything is gone by 10^150 years. If the existence of Hawking radiation is ever confirmed observationally or experimentally in nano black holes made by particle physics in the LHC then Hawking will be given a Nobel prize. Most physicists think his model is correct, but the Nobel committee requires experimental verification. A restriction that they don't seem to place on the Economics prize! I thought a definition of a black hole was that neither mass nor energy could ever leave, so I must forget that "definition" That would be true of a purely classical black hole. But we know that we live in a universe where on the very smallest scales quantum mechanics rules the roost. There is at present no single theory that completely unifies all the forces of nature. The borders where quantum effects collide with extreme gravity of black holes in GR are tricky. It is still a very good approximation to black for all practical purposes where stellar mass (or heavier) black holes are concerned. I liked his falling cup and falling laser beam extension of the falling feather and lead weight under gravity , if earth was big enough to observe both , on last night's Sky at Night Somehow over the decades I'd never some across his first item, the Chankillo calendar http://hila.webcentre.ca/projects/chankillo I hadn't seen that one either, but I expect there are plenty of places where ancient people in settlements noticed the sunrise over a particular hill being coincident with the seasons. Or in the case of ancient Egypt Sirius being just visible heralding the Nile floods. Exotic to build so many towers though. Regards, Martin Brown |
#5
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Black holes evaporating?
Martin Brown wrote:
On 07/03/2011 08:22, N_Cook wrote: Brian Cox on his prog last night twice mentioned this, as near enough the last throes of the dying universe - how does a black hole "evaporate"? Hawking radiation - virtual particle anti-particle pairs occur as fluctuations in the pure vacuum. If one falls in and the other escapes to infinity then the black hole loses mass-energy in the process. Casimir effect is related and observed in lab experiments. http://en.wikipedia.org/wiki/Casimir_effect It is amazing how early on this was measured! Slightly less handwaving version online at: http://casa.colorado.edu/~ajsh/hawk.html http://en.wikipedia.org/wiki/Hawking_radiation The lower the BH mass the higher its effective radiation temperature which means that the final signature of a BH going pop is expected to be quite violent. Big ones take almost forever to evaporate but are expected to do so eventually almost everything is gone by 10^150 years. If the existence of Hawking radiation is ever confirmed observationally or experimentally in nano black holes made by particle physics in the LHC then Hawking will be given a Nobel prize. Most physicists think his model is correct, but the Nobel committee requires experimental verification. A restriction that they don't seem to place on the Economics prize! Regards, Martin Brown .... but economics isn't a science so it can't experimentally validated :-) Larry |
#6
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Black holes evaporating?
On 07/03/2011 10:41, N_Cook wrote:
Martin wrote in message ... On 07/03/2011 08:22, N_Cook wrote: Brian Cox on his prog last night twice mentioned this, as near enough the last throes of the dying universe - how does a black hole "evaporate"? Hawking radiation - virtual particle anti-particle pairs occur as fluctuations in the pure vacuum. If one falls in and the other escapes to infinity then the black hole loses mass-energy in the process. Casimir effect is related and observed in lab experiments. http://en.wikipedia.org/wiki/Casimir_effect It is amazing how early on this was measured! Slightly less handwaving version online at: http://casa.colorado.edu/~ajsh/hawk.html http://en.wikipedia.org/wiki/Hawking_radiation The lower the BH mass the higher its effective radiation temperature which means that the final signature of a BH going pop is expected to be quite violent. Big ones take almost forever to evaporate but are expected to do so eventually almost everything is gone by 10^150 years. If the existence of Hawking radiation is ever confirmed observationally or experimentally in nano black holes made by particle physics in the LHC then Hawking will be given a Nobel prize. Most physicists think his model is correct, but the Nobel committee requires experimental verification. A restriction that they don't seem to place on the Economics prize! Regards, Martin Brown I thought a definition of a black hole was that neither mass nor energy could ever leave, so I must forget that "definition" I liked his falling cup and falling laser beam extension of the falling feather and lead weight under gravity , if earth was big enough to observe both , on last night's Sky at Night Somehow over the decades I'd never some across his first item, the Chankillo calendar http://hila.webcentre.ca/projects/chankillo The astronomical significance of the towers only seems to have been recognised in 2007 |
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