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Author Topic: What Is the Temperature Of a Black Hole ?  (Read 569 times)

Offline neilep

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What Is the Temperature Of a Black Hole ?
« on: 18/09/2016 14:35:12 »
Dearest Dark Cavity Dwellers,

As a sheepy I of course am fascinated by black holes. I have my own in use about three times a day...nnnnggghhhhhhh !!!!


Seeing as they seem to have some gravity issues i thought it might be interesting to give one a full medical and take it's temperature .See piccy attached !

Sheeeesh !!!...I wish someone had told me that they make the worst kind of patients and not willing to cooperate at all. I tried to coax it to open wide so i could take it's temp but it was not having it !!...very frustrating !!.. I left my invoice including travel expenses and came home !!

Is the temperature of a Black Hole a meaningless kweschun because I assume it's not the easiest thing to obtain if obtainable at all !!

whajafink ?

What is the temperature of a black hole ?


hugs and shmishes


mwah mwah mwah



neil
xxxxxxxx


Holes in Space are really black
Social skills are what they lack
If one is ill I'm not going back !!

« Last Edit: 18/09/2016 14:37:45 by neilep »


 

Offline CPT ArkAngel

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Re: What Is the Temperature Of a Black Hole ?
« Reply #1 on: 19/09/2016 22:00:38 »
The temperature inside the 'event horizon' is meaningless. But Hawking found an approximation of the actual temperature at the event horizon for a non rotating black hole. But just outside the event horizon, matter infalling can raise the temperature to high extremes...

http://xaonon.dyndns.org/hawking/

Nice to see the sheepy is well and alive... :)

What is the temperature of a laser beam for a photon in the beam?


« Last Edit: 19/09/2016 22:13:13 by CPT ArkAngel »
 
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Offline neilep

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Re: What Is the Temperature Of a Black Hole ?
« Reply #2 on: 20/09/2016 12:00:33 »
thank ewe so much CPT ArkAngel

very much appreciate the link to the hawking calculator ........and kind words !! :)
 

Offline evan_au

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Re: What Is the Temperature Of a Black Hole ?
« Reply #3 on: 20/09/2016 12:20:30 »
Astronomical black holes are pretty cool.

Quote from: Wikipedia
A black hole of one solar mass (M☉) has a temperature of only 60 nanokelvin (60 billionths of a kelvin); in fact, such a black hole would absorb far more cosmic microwave background radiation than it emits. A black hole of 4.5 1022 kg (about the mass of the Moon, or about 13 micrometers across) would be in equilibrium at 2.7 kelvin, absorbing as much radiation as it emits.

See: https://en.wikipedia.org/wiki/Hawking_radiation#Overview

Don't go near a black hole while it is eating - they like their food hot; so hot it emits X-Rays! It will give you a bad case of sunburn.
See: https://en.wikipedia.org/wiki/Accretion_disk#Manifestations

There is a theoretical possibility of micro-black holes left over from the Big Bang. These would explode like a hydrogen bomb - really hot stuff!
 
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Offline syhprum

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Re: What Is the Temperature Of a Black Hole ?
« Reply #4 on: 20/09/2016 14:03:29 »
Presumably a shrinking black hole would explode when its mass fell to the Planck limit 22 micrograms about one hundredth thousandth the energy of the Hiroshima bomb nothing like Hydrogen bomb levels
 
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Offline evan_au

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Re: What Is the Temperature Of a Black Hole ?
« Reply #5 on: 20/09/2016 19:40:44 »
Quote from: Syphrum
Presumably a shrinking black hole would explode when its mass fell to the Planck limit 22 micrograms about one hundredth thousandth the energy of the Hiroshima bomb nothing like Hydrogen bomb levels
Quote from: Steven Hawking, 1977
The final stage of the evaporation of a black hole would proceed so rapidly that it would end in a tremendous explosion...an energy equivalent to about 10 million one-megaton hydrogen bombs.
See: http://www.phys.uwosh.edu/rioux/thermo/pdf/Black%20Holes%20--%20Hawking.pdf

Of course, there are still a lot of unknowns:
- Hawking mentions that if there are more massive subatomic particles than the ones we know, the explosion could be even greater
- If some assumptions about string theory turn out to be true, the rate of black hole evaporation could be lower than Hawking predicted
- It would be nice to have a micro black hole to study - just not in my galactic back yard!

See: https://en.wikipedia.org/wiki/Primordial_black_hole#Possible_detection
 

Offline syhprum

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Re: What Is the Temperature Of a Black Hole ?
« Reply #6 on: 20/09/2016 19:52:37 »
Ignorant people are for ever questioning Einstein I dare to question Hawkins, how can 22 micrograms explode with the force of millions of Hydrogen bombs
Is there an extra hot part of Hell for such heratics
 

Offline CPT ArkAngel

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Re: What Is the Temperature Of a Black Hole ?
« Reply #7 on: 20/09/2016 23:12:40 »
They should have said a tiny black hole. They are not talking about a Planck mass black hole, just a black hole with a size small enough to 'burst' or 'evaporate' in less than a second or something like it (mass = 228 metric tons; radius 3.4x10^-22 meter). Any black hole has the same ending according to Hawking. Any black hole with a minimum size at its birth will end in a huge explosion. We haven't seen any yet (?)... A black hole of 1.7x10^8 metric tons will finish 'evaporating' in an exponential burst 13 billion years later...

I doubt that a Planck mass black hole may take form in reality.

« Last Edit: 21/09/2016 08:40:33 by CPT ArkAngel »
 

Offline syhprum

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Re: What Is the Temperature Of a Black Hole ?
« Reply #8 on: 21/09/2016 09:03:47 »
I made the mistake of assuming the rate of evaporation of a black hole was linear whereas one should assume that it happens at an ever increasing rate.
I leave it those better versed in mathematics to calculate at what mass the final conversion of mass to energy will take place but no doubt Hawkins knows better than me   
 

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Re: What Is the Temperature Of a Black Hole ?
« Reply #8 on: 21/09/2016 09:03:47 »

 

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