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If no singularity, what’s inside a big black hole? 
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#127
Oct3111, 03:45 AM

P: 216

The Black Hole is an object with a maximum entropy for a given mass of the object.
Each particle is entangled with a number of nonlocal information on a longest distance = a circle of the object / Compton wavelength = [2 pi R / (h/mc)] in an object with a radius R and the whole mass M. How many bits of the information may contain M/m particles with an average mass "m" in a Black Hole where M=c^2 R /2G (M/m) [2 pi R / (h/mc)] = pi R^2 / (hG/c^3 ) = A /4 lp^2 Where A is a surface of the Event Horizon of the Black Hole and lp^2 is Planck length squared. It is interesting, that the information capacity of the Black Hole increases not with its volume but with its surface. Therefore the average density of the Black Hole Like Object decreases if the mass of the object increases. http://en.wikipedia.org/wiki/Black_hole_thermodynamics 


#128
Oct3111, 04:19 AM

P: 4,512

It would be very satisfying, if at some time in the not too distant future, discussions of black holes did not contain meaningless temporal verbage. The word "is" is the current tense of the verb "to be". "Will be" is the future tense the verb "to be", ect.
The use of such key words in general relativity, and even special relativity, should be specified with clarity or a declarative statement about black holes is so perfectly ambiguous it could mean a number of different things to diffenent readers. If you wish to discuss back holes, youall should be aware that the verbs "is", "was", "will be", "never was", "never will be", etcetera are not physically meaningful without greater specification nor universally understood within your own personal gestalt. spacetime is not flat. 


#129
Oct3111, 10:39 AM

P: 136

"In the beginning there was nothing, which exploded." — Terry Pratchet
Why there should be something is a very tough question. 


#130
Nov1911, 09:06 AM

P: 8

So, could we turn the question back like that: why should something be there in the future and/or past? (? Après nous la ...) 


#131
Dec511, 04:43 PM

P: 136

To sum up my position, there’s a lot of confusion out there about black holes, mostly caused by so many people repeating the illogical argument that black holes are a point singularity. They use the incorrect argument that anything within the event horizon (Schwarzchild radius) must have energy greater than mc^2 if it is not to proceed to the center. This is getting facts backwards. The maximum gravitational energy of a star is (0.6GM^2)/R. If ALL a star’s energy goes into creating pressure, that energy would equal Mc^2 maximum. Setting Mc^2 = (0.6GM^2)/R results in the minumum radius R for anything, or any star, including the star in a black hole, of R(min) = (0.6GM)/(c^2). This is 30% of the Schwarzchild radius. Any smaller radius would mean the gravitational energy would have to exceed Mc^2.
Actual stars in nature have density profiles of about 1/(r^2), resulting in a gravitational energy of almost exactly (1.0GM^2)/R, or simply (GM^2)/R. And if all (or almost all) the mass inside a black hole were to go “relativistic” (I hate using that term), the total energy creating pressure would be (Mc^2)/3. The viral theorem, which is used to calculate the size of gravitational objects, says the energy creating pressure equals half the gravitational energy, or (Mc^2)/3 = (GM^2)/2R. This gives the radius of a star inside a black hole of R = (1.5GM)/(c^2), which is 75% of the Schwarzchild radius. It doesn’t matter what this star in a black hole is made of, quark matter, radiation, whatever; thats the size. Other basic math shows that the core density and core pressure of a star in a small black hole (of a few solar masses) is about 8 times the core density and core pressure of a neutron star of a few solar masses. Nothing profound or unrealistic about this. Also, if the star inside a black hole has a “atmosphere” of radiation, it would be small and would not affect the above calculations. This hypothetical radiation wouldn’t come anywhere near the Schwarzchild radius and would be contained in much the same way the earth contains its atmosphere. An interesting result of the above is if two EQUAL mass orbitting black holes merge, there can be a huge ejection from them or even annihilation of the 2 black holes. Hmmm. Its only a matter of time before black hole mergers will be observed. Lets hope some observed mergers are of equal sized ones. Finally, I don’t know why so many people use the Tolmann Volkov equation for a black hole. Not only does it give the wrong answer (neutron star collapse at 0.7 solar mass), but its conclusion of infinate pressure at the Schwarzchild radius is kind of obvious nonsense. But I do agree with Tolmann Volkov that the contents of a black hole can be analyzed as a gas, but one where the "gas" pressure P = (rho/3)c^2. Sorry for the length of this. If anyone has any questions on the above email Berniepie at aol.com. 


#132
Dec511, 07:32 PM

P: 136

Minor correction to the above: The core density of a resulting black hole is about 20 times the core density of a neutron star, and the core pressure of the black hole is about 50 times the core pressure of a neutron star (of a few solar masses). Shouldn't do calculations in my head. Doesn't change anything; if you can accept the densities and pressures in a neutron star, these densities/pressures are also imaginable. The biggest weird thing is that if a neutron star collapses to about 3/8 its size (in terms of radius), the resulting star is 25% smaller than the Schwarzchild radius and nothing can escape unless 2 equal size black holes merge.



#133
Jan1212, 08:35 AM

P: 136

Final tweaking: I think a thin neutron crust is unlikely since that would probably require a temperature gradient. Also, if the core is very large (a more likely density profile) the gravitational energy energy could be as low as (4GM^2)/(5R), resulting in a star radius of only (1.2GM)/(c^2) instead of R = (1.5GM)/(c^2). Bottom line is a nonrotating star of relativistic material would have a radius between 60  75% of the Schwarzchild radius, which with the bulging effect should be enough for a massive ejection to occur if two approximately equal size orbiting black holes merge.
This also presents a different possible “origin” of our universe other than the big bang. Consider if two massive orbiting black holes merged, with each approximately half the mass of the universe. They would eject relativistic material for millions of years. 


#134
Jan1412, 04:47 AM

P: 8

One possible bet is, there might be just an indetermined state (like future) because "normal" time is meshed up with other dimensions. It is fun to think about this at least.
If so, it's probably even more fun to build a ring around an extra large black hole (large enough, so the gravitation on the edge is affordable). Now, let's sit on this ring and push a mirror inside with a stick, beyond the event horizon ... OK, OK, let's just look at the ZeldovichStarobinskyBekensteinHawking radiation. Could we see and hear the future and/or past? Anyway, this scenario looks and feels somewhat like an oracle from any mythology... 


#135
Jan1412, 08:19 AM

P: 136

I think your example of pushing a mirror inside the event horizon of a large black hole illustrates the sorry state of affairs of contemporary black hole analysis. The Tolman–Oppenheimer–Volkoff equation is normally quoted, and this equation results in infinite pressure inside the event horizon. So as an example, if we consider a 10 million solar mass black hole, the gravitational acceleration at the event horizon would be about one millionth that at the surface of a neutron star. The surface of a neutron star obviously doesn't have infinite pressure.



#136
Jan1512, 02:18 AM

P: 95

How can the gravitational acceleration at an event horizon be smaller than at the surface of a neutron star ? 


#137
Jan1512, 02:34 AM

P: 95

Anyway, let's for argument's sake pretend it was possible to do such a thing  you wouldn't be able to see anything reflected off the part of the mirror which is at and inside the event horizon. Also, you would not be able to pull the mirror back out. Basically, this whole thing is a waste of time. 


#138
Jan1512, 07:48 AM

P: 407

There is a recent review by Mathur that is very clearly witten and a pleasure to read:
http://arXiv.org/pdf/1201.2079 From his Fuzzball viepoint, these questions eg about a singularity are irrelevant. 


#139
Jan1612, 04:25 AM

P: 8

Thank you for positive feedback. I, too, would say: the points of view of avatar Bernie G might sometimes be a bit unanticipated, but they are fun to read and certainly on the positive side of this pleasant forum.



#140
Jan1612, 04:43 AM

P: 8

Dear person behind avatar Markus Hanke
Thank you for your attention. I am pleased to see, my text was interesting for you. But regrettably (probably my grammar was a bit too heavyish), there is some unnecessary misunderstanding here. I will try to use less grammar next time; but you, too, could you please next time consider reading a sentence from the beginning to the end (and if you don't get the point, then reading again and doing some thinktank work) ... before you try to make fun of it, OK? Hint: compound sentences include often many parts and you should read all of these parts. You should not cut out 1 little piece and advertise this as the meaning of a compound sentence. 


#141
Jan1612, 09:21 AM

P: 95

So again, please accept my public apology. I genuinely did not mean it to come across like this. 


#142
Jan1612, 09:21 AM

P: 136

“How can the gravitational acceleration at an event horizon be smaller than at the surface of a neutron star ?”
Because gravitational acceleration varies as the inverse of r squared. One of us is making a mistake. I was under the impression that distant supermassive black holes (10 billion solar masses) “disappeared” because the gravitational acceleration at the event horizon is so small (and the curvature so large) that infalling material doesn’t even radiate until it is well within the black hole. Hence I volunteer to sit on the ring and bravely stick my toes inside the event horizon of a trillion solar mass black hole, where the gravity (gulp) should be about as strong as in California. To challange the staus quo even further, here in a nutshell is my minority viewpoint about the size of a star composed of relativistic material inside a black hole: The gravitational energy could be as low as (4GM^2)/(5R) for a typical density profile, or possibly as high as (GM^2)/R (unlikely) if the star has a high density core. The total energy creating pressure would be (Mc^2)/3. Using the viral theorem (the energy creating pressure equals half the gravitational energy), a nonrotating star of relativistic material would have a radius as small as (1.2GM)/(c^2) or as large as (1.5GM)/(c^2), or between 60  75% of the Schwarzchild radius. If this model is true, it could be verified someday by the observation of the merger of two approximately equal mass black holes: a massive ejection from the relativistic stars would occur. 


#143
Jan1612, 09:32 AM

P: 95




#144
Jan1612, 09:42 AM

P: 136

"the gravitational acceleration at the event horizon for a BH of equal mass must be much stronger than at the surface of the neutron star"
I should have been clearer and was referring to a typical neutron star of one or two solar masses. What I said was: "if we consider a 10 million solar mass black hole, the gravitational acceleration at the event horizon would be about one millionth that at the surface of a neutron star." 


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