I know that information is meant to be lost/unavailable inside a black hole, but what would the temperature be in theory? The latest issue of Science Illustrated says “it is -273, almost absolute zero”
Stealth said:
I know that information is meant to be lost/unavailable inside a black hole, but what would the temperature be in theory? The latest issue of Science Illustrated says “it is -273, almost absolute zero”
ithis question isn’t far off “what happen’s to a photon in a BH?
shirley everything inside a BH has only one way to go?
Boris said:
shirley everything inside a BH has only one way to go?
but what is a photon in between event horizon and,,, where ever they go?
a photon is a photon. iws.
Boris said:
a photon is a photon. iws.
i thought a state of -273 might effect the conductivity of the environment altering how they are travelling maybe shrug
Riff-in-Thyme said:
Boris said:
a photon is a photon. iws.
i thought a state of -273 might effect the conductivity of the environment altering how they are travelling maybe shrug
in the BH or out side of it?
inside the EH, the first one.
Stealth said:
I know that information is meant to be lost/unavailable inside a black hole, but what would the temperature be in theory? The latest issue of Science Illustrated says “it is -273, almost absolute zero”
What theory? We don’t have one yet. :) GR claims to tell us stuff about what happens inside a BH, but it takes no account of quantum effects, so we don’t trust the numbers it gives us.
However, we do have a relativistic quantum theory for what happens at the event horizon. We’re not totally confident in it, but most astrophysicists are happy to accept it until we do get a proper quantum gravity theory. According to Hawking, black holes radiate like perfect black bodies with a characteristic temperature inversely proportional to their mass. For stellar-sized black holes, that temperature is in the nanokelvin range, i.e., around one billionth of a degree above absolute zero. Eg, a BH 3 times the mass of our Sun would have an event horizon with an area of around 987 square kilometres, and a Hawking temperature of just over 2.0E-8 kelvin, or 20 nanokelvin.
See http://en.wikipedia.org/wiki/Hawking_radiation#Emission_process
And here’s the black hole calculator I used to find the figures quoted above:
http://xaonon.dyndns.org/hawking/
PM 2Ring said:
Stealth said:
I know that information is meant to be lost/unavailable inside a black hole, but what would the temperature be in theory? The latest issue of Science Illustrated says “it is -273, almost absolute zero”
What theory? We don’t have one yet. :) GR claims to tell us stuff about what happens inside a BH, but it takes no account of quantum effects, so we don’t trust the numbers it gives us.
However, we do have a relativistic quantum theory for what happens at the event horizon. We’re not totally confident in it, but most astrophysicists are happy to accept it until we do get a proper quantum gravity theory. According to Hawking, black holes radiate like perfect black bodies with a characteristic temperature inversely proportional to their mass. For stellar-sized black holes, that temperature is in the nanokelvin range, i.e., around one billionth of a degree above absolute zero. Eg, a BH 3 times the mass of our Sun would have an event horizon with an area of around 987 square kilometres, and a Hawking temperature of just over 2.0E-8 kelvin, or 20 nanokelvin.
See http://en.wikipedia.org/wiki/Hawking_radiation#Emission_process
And here’s the black hole calculator I used to find the figures quoted above:
http://xaonon.dyndns.org/hawking/
Stealth said:
I guess that sounds fair enough for the black body radiation of a BH, but the headline made it sound like the internal temperature was -273. It is possible for a normal object, say steel wrapped in insulation to have a different internal temp compared to its BB radiative temp. But what about a BH? Of course a BHs insulation is pretty damn impressive, a very high R rating.
:)
Yeah, we really don’t have a clue what the internal temperature of a BH is, or even if the concept of temperature is even applicable in there. According to pure GR, there is nothing inside a stable BH except at the core, which is a perfect mathematical singularity. We suspect that all the disorder of a BH is “captured” by the EH, so the core itself has no disorder & hence has a temperature of zero. OTOH, a thing of extreme density and non-zero energy content ought to have an extreme temperature… and when a BH evaporates by Hawking radiation it gets hotter & hotter as it loses mass. At the last few seconds, its temperature would be hotter than anything else in the cosmos (apart from the early moments of the BB).
So take your pick. :)
Stealth said:
I know that information is meant to be lost/unavailable inside a black hole, but what would the temperature be in theory? The latest issue of Science Illustrated says “it is -273, almost absolute zero”
The wouldn’t mean the temperature “inside” a black hole, they’d mean the temperature “of” a black hole, ie. calculated from the entropy. Yes, for galactic mass black holes the temperature is indistinguishable from absolute zero. The temperature of a stellar mass black hole is also exceptionally small, 6*10^-8 Kelvin.
Just a few days ago I was looking into a different way of calculating the temperature of a black hole, the temperature calculated from the radiation from the hot matter in the accretion disk. For the black hole Cygnus X-1 this radiation is 10^37 ergs/s, which ought to be able to be used to get a temperature from Wein’s Law with a black hole radius of 3 km. That’s the effective temperature outside a black hole.
Stealth said:
I know that information is meant to be lost/unavailable inside a black hole, but what would the temperature be in theory? The latest issue of Science Illustrated says “it is -273, almost absolute zero”
The wouldn’t mean the temperature “inside” a black hole, they’d mean the temperature “of” a black hole, ie. calculated from the entropy. Yes, for galactic mass black holes the temperature is indistinguishable from absolute zero. The temperature of a stellar mass black hole is also exceptionally small, 6*10^-8 Kelvin.
Just a few days ago I was looking into a different way of calculating the temperature of a black hole, the temperature calculated from the radiation from the hot matter in the accretion disk. For the black hole Cygnus X-1 this radiation is 10^37 ergs/s, which ought to be able to be used to get a temperature from Wein’s Law with a black hole radius of 3 km. That’s the effective temperature outside a black hole.
For a calculator that give the temperature of a black hole, together with equations, see http://xaonon.dyndns.org/hawking/. The mass of the Sun is 2E+30 kg.