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Black holes evaporating?



 
 
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  #1  
Old March 7th 11, 09:22 AM posted to uk.sci.astronomy
N_Cook
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Posts: 86
Default 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"?

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  #2  
Old March 7th 11, 10:15 AM posted to uk.sci.astronomy
Martin Brown
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Posts: 1,707
Default 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  
Old March 7th 11, 11:41 AM posted to uk.sci.astronomy
N_Cook
external usenet poster
 
Posts: 86
Default 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  
Old March 7th 11, 12:15 PM posted to uk.sci.astronomy
Martin Brown
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Posts: 1,707
Default 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  
Old March 7th 11, 07:32 PM posted to uk.sci.astronomy
Larry Stoter
external usenet poster
 
Posts: 2
Default 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  
Old March 7th 11, 11:16 PM posted to uk.sci.astronomy
OG
external usenet poster
 
Posts: 780
Default 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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