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Author Topic: Black Hole and Singularities  (Read 13929 times)

Offline DoctorBeaver

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« Reply #25 on: 29/01/2008 07:48:28 »
Hi guys,

I am getting very nice info on black holes from the Cambridge Relativity site http://www.damtp.cam.ac.uk/user/gr/public/

All the best stuff about everything is at Cambridge  [^]
 

Offline Saganist

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« Reply #26 on: 03/02/2008 04:25:46 »
Hi guys,

I am wondering about the big bang singularity. Most black holes are very cold and I assume the singularities of these are near or at absolute zero.

So where does the immense heat of the very young universe come from? How can matter be so condensed and still be so hot? Is this heat a result of the BB singularity's explosion?

Cheers.

PH
 

Offline DoctorBeaver

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« Reply #27 on: 03/02/2008 08:42:51 »
The heat in the very young universe came from the enormous density and the level of energy.

As for what the conditions were at the moment of the big bang itself, or even prior to that,

 

Offline Dick1038

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« Reply #28 on: 05/02/2008 17:58:17 »
BH's are very cold on the outside, but maybe very hot inside.  Matter falling in heats up and radiates x-rays. I would assume that it doesn't cool down much before it crosses the EH.  The heat can't get out once inside.
 

Offline Saganist

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« Reply #29 on: 11/02/2008 05:02:04 »
Hi Doc,

Heat as a result of energy condensation I can understand that. Heat from matter increasing in density, is for me, a little harder ot understand. If density prevents atomic movement, the matter and its density should not create heat. However I can guess that whatever heat was once present in matter's state before it crosses the event horizon will be shed as radiation.

Somewhere between the event horizon and the singularity, increasing matter density must cross some point where all remaining heat is stripped from the matter constituent of the singularity. Much heat is stripped away from matter's encounter with the event horizon, but if any remains it would radiate away from the matter as it approaches absolute zero.

In the big bang's case, my best guess, from your answers are that heat had to go somewhere, so it forced the creation a universe to contain it?

Cheers.

PH
 

Offline DoctorBeaver

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« Reply #30 on: 11/02/2008 07:48:51 »
Compressing anything will increase its temperature. Even squeezing a rubber ball in your hand will make it hotter (albeit only by a tiny amount).

Imagine yourself standing in your garden, minding your own business, listening to the little birdies singing away in the trees when someone comes along and tries to push you aside.

"I'm not having this!", you think to yourself, and so you resist by pushing back against the dastardly intruder. So there you both are, deadlocked; neither 1 of you giving an inch.

But you are both expending energy even though you are not moving very much.

The same happens when you compress matter. Particles don't like being squeezed together; and by resisting they are generating heat.

That is probably complete rubbish, but it sounds good to me  :D
 

Offline lightarrow

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« Reply #31 on: 11/02/2008 18:41:00 »
Compressing anything will increase its temperature. Even squeezing a rubber ball in your hand will make it hotter (albeit only by a tiny amount).

Imagine yourself standing in your garden, minding your own business, listening to the little birdies singing away in the trees when someone comes along and tries to push you aside.

"I'm not having this!", you think to yourself, and so you resist by pushing back against the dastardly intruder. So there you both are, deadlocked; neither 1 of you giving an inch.

But you are both expending energy even though you are not moving very much.

The same happens when you compress matter. Particles don't like being squeezed together; and by resisting they are generating heat.

That is probably complete rubbish, but it sounds good to me  :D

Interesting. Physicists would like to explain human behaviour in terms of elementary particles, you would like to explain particles' behaviour in terms of human psychology!
(Example of different viewpoints  :)).
 

Offline DoctorBeaver

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« Reply #32 on: 11/02/2008 18:45:22 »
Compressing anything will increase its temperature. Even squeezing a rubber ball in your hand will make it hotter (albeit only by a tiny amount).

Imagine yourself standing in your garden, minding your own business, listening to the little birdies singing away in the trees when someone comes along and tries to push you aside.

"I'm not having this!", you think to yourself, and so you resist by pushing back against the dastardly intruder. So there you both are, deadlocked; neither 1 of you giving an inch.

But you are both expending energy even though you are not moving very much.

The same happens when you compress matter. Particles don't like being squeezed together; and by resisting they are generating heat.

That is probably complete rubbish, but it sounds good to me  :D

Interesting. Physicists would like to explain human behaviour in terms of elementary particles, you would like to explain particles' behaviour in terms of human psychology!
(Example of different viewpoints  :)).

You can always rely on the beaver to look at things with a perverse viewpoint!  :D

I find that trying to explain things in different ways helps me to understand them better too.
 

Offline Saganist

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« Reply #33 on: 12/02/2008 04:46:09 »
Hi Doc,

But once matter reaches near the Bose Einstein condensate temperature, it should begin to cool down?

Cheers.

Saganist
 

Offline DoctorBeaver

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« Reply #34 on: 12/02/2008 07:47:56 »
I don't know. I haven't looked at BE condensates very much. We'll have to wait for the likes of SoulSurfer, AnotherSomeone or Lightarrow (apologies to anyone I've missed) to answer that.
 

Offline lightarrow

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« Reply #35 on: 12/02/2008 19:05:05 »
Hi Doc,

But once matter reaches near the Bose Einstein condensate temperature, it should begin to cool down?

Cheers.

Saganist

It's (quite) the reverse: some kind of matter, in specific conditions, starts to form a BEC (Bose Einstein Condensate) if you cool it down to very low temperatures.
 

Offline Brex

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« Reply #36 on: 16/02/2008 16:45:34 »
I read through all the views above and my imagination tended to make two and two equal eleven. In particular the observation that a star rotating beyond a certain velocity cannot collapse to a singularity stirred my thoughts.

Consider that much of the rotating mass of such a star approached light velocity whence it's mass tended to infinite (and I subscribe to the view that this will be inertial mass rather than gravitational mass), then the probability will be that a single dimensional ring will be formed rather than a singularity. Gravity within the plane of the ring will be neutral and it will be weakened on either side, more so nearer the rotational axis. There will be formed an internal event horizon which could join the external one at the ‘poles’ and hence a hole from which some of the plasma, ejected from the ring which is in contact with the internal event horizon, can escape.

Opposing spiraling plasma jets have been observed.

Coo-coo.  Perhaps they will accept me for the post of stoker on Red Dwarf!
 

Offline Soul Surfer

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« Reply #37 on: 16/02/2008 22:29:28 »
You should look up Kerr black holes which describes precisely what you are suggesting
 

Offline Brex

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« Reply #38 on: 17/02/2008 11:59:26 »
I've taken your advice SS but only to the extent of using wikipedia. I did suppose that the logic had already been explored but saw no mention in those readings of zero gravity within the plane of the ring and that therefore the internal event horizon being in contact with it. This,I'm pretty sure, is fact.The merging of the internal and external event horizons and subsequent possibilities is pure speculation.Perhaps this has already been considered and rejected.If not I was hoping that someone out there could do the sums.   
 

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« Reply #38 on: 17/02/2008 11:59:26 »

 

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