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Author Topic: Are there only galactic sized black holes?  (Read 9873 times)

Offline jeffreyH

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Are there only galactic sized black holes?
« on: 22/04/2015 18:36:05 »
I have come to the conclusion that 3 times the solar mass is far too small to create a viable black hole and that only masses large enough to form galactic core black holes will be stable. I would appreciate comments on this viewpoint. If you think it's wrong please explain why.


 

Offline chiralSPO

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Re: Are there only galactic sized black holes?
« Reply #1 on: 22/04/2015 19:03:14 »
My understanding is that the 3 solar mass limit has to do with the compressibility of matter, and that one must have at least that amount of mass for the gravitational field to overcome the resistance.

This limit does not take into account Hawking radiation or any other mechanisms of decomposition other than expansion into non-degenerate matter. However, my understanding is that even very small black holes would still require many billions of years (at least) to evaporate to the 3 solar mass limit. This, of course will depend on the environment as well as the black hole itself.

Why do you think only huge black holes could be stable? And what is your definition of stable?
 

Offline PmbPhy

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Re: Are there only galactic sized black holes?
« Reply #2 on: 22/04/2015 20:12:40 »
Quote from: jeffreyH
I have come to the conclusion that 3 times the solar mass is far too small to create a viable black hole and that only masses large enough to form galactic core black holes will be stable. I would appreciate comments on this viewpoint. If you think it's wrong please explain why.
I disagree. I can't even imagine what you mean by a "viable" or "stable black hole. Once a black hole is formed its impossible to be anything else. It cannot turn into something else by any means.

A stellar black hole is a black hole formed formed by the gravitational collapse of a massive star. Such stars have a mass from about 5 to several tens of solar masses. See: http://en.wikipedia.org/wiki/Stellar_black_hole
 

Offline jeffreyH

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Re: Are there only galactic sized black holes?
« Reply #3 on: 22/04/2015 20:20:19 »
Quote from: jeffreyH
I have come to the conclusion that 3 times the solar mass is far too small to create a viable black hole and that only masses large enough to form galactic core black holes will be stable. I would appreciate comments on this viewpoint. If you think it's wrong please explain why.
I disagree. I can't even imagine what you mean by a "viable" or "stable black hole. Once a black hole is formed its impossible to be anything else. It cannot turn into something else by any means.

A stellar black hole is a black hole formed formed by the gravitational collapse of a massive star. Such stars have a mass from about 5 to several tens of solar masses. See: http://en.wikipedia.org/wiki/Stellar_black_hole

I know what you are saying but these are theoretical. We have no definitive evidence.
 

Offline jeffreyH

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Re: Are there only galactic sized black holes?
« Reply #4 on: 22/04/2015 20:21:34 »
My understanding is that the 3 solar mass limit has to do with the compressibility of matter, and that one must have at least that amount of mass for the gravitational field to overcome the resistance.

This limit does not take into account Hawking radiation or any other mechanisms of decomposition other than expansion into non-degenerate matter. However, my understanding is that even very small black holes would still require many billions of years (at least) to evaporate to the 3 solar mass limit. This, of course will depend on the environment as well as the black hole itself.

Why do you think only huge black holes could be stable? And what is your definition of stable?

I don't believe that compressibility of matter is the only consideration.
 

Offline evan_au

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Re: Are there only galactic sized black holes?
« Reply #5 on: 22/04/2015 22:31:02 »
No-one has actually "seen" a black hole. However, we can infer that they exist because we can see the orbital motion of nearby objects, and we can detect X-rays emitted by an accretion disk. Even the galactic-sized black hole at the center of our galaxy is hard to spot, because it appears to have been on a diet for thousands of years.

In the case of the galactic-mass black hole, we know of nothing that could withstand this intense gravitational tug without becoming a black hole.

In the case of stellar mass black holes, there is a known candidate for an alternative interpretation: neutron stars*. They are extremely dense, and will display much of the same orbital behavior and X-Ray emissions as a black hole accretion disk. It is possible to identify some neutron stars by their occasional outbursts or pulsing, but it is not possible to be sure that a dense stellar companion is not a pulsar for which we haven't seen an outburst (yet).

So the question is really: How much gravitational pressure can a neutron star stand before it collapses further, into a black hole? We don't know much experimentally about the physics of dense neutron liquids, but there are estimates, based on work by Tolman. They suggest that neutron stars of more than 3 solar masses will collapse under their own weight.

Some ways we may be able to distinguish these endpoints of a massive star:
  • Look at the distribution of masses of neutron stars and white dwarf stars. If we see a cutoff at 2-3 solar masses, that is an indication that anything more massive has collapsed into a black hole.
  • There is a discrepancy between the expected and observed number of supernovae seen in our galaxy - by a factor of around 4:1. If a star collapsed to a neutron star, we would see the supernova and detect neutrinos; however, if it were consumed from the inside by a black hole without passing through a neutron star stage, we may see very little of this. Catching one of these "missing" supernovae may provide some direct evidence.
  • There has been some recent observational evidence of detection of "frame dragging" in the accretion disk around an X-Ray source. This effect is much more pronounced in the intense gravitational field around a black hole, compared to a neutron star. So further analysis of these time-varying X-Ray emissions may allow us to distinguish black holes from neutron stars. 

*There is also a theoretical candidate: Quark stars, but we know even less about the behavior of superdense quarks than we do about superdense neutrons.
 

Offline PmbPhy

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Re: Are there only galactic sized black holes?
« Reply #6 on: 22/04/2015 23:05:12 »
Quote from: jeffreyH
I know what you are saying but these are theoretical. We have no definitive evidence.
What? Are you kidding me, Jeff? Buddy! Pal-o-mine!! When you pose a question like this it, in my very humble opinion, reveals a serious problem with your grasp of the philosophy of physics and the scientific method. We do indeed have a great deal of "definitive" evidence that what we predict using general relativity will be born out by observation. Testing a theory means to use the theory to make predictions which can then be tested in the lab or observations can be made and compared with predictions. However it would be an error to think that only the exact things that we test are indeed what we can have faith on regarding the theory.

For example: the following tests have been made against the general theory of relativity. From:
http://en.wikipedia.org/wiki/Tests_of_general_relativity

Perihelion precession of Mercury
Deflection of light by the Sun
Gravitational redshift of light
Gravitational lensing
Light travel time delay testing
The equivalence principle
Frame-dragging tests
Strong field tests: Binary pulsars
Cosmological tests

All of those tests and observations have were in complete agreement with the predictions made by general relativity. Just because the exact thing that is test and subsequently confirmed isn't the exact same thing that we're interesting in, it doesn't mean that our testing didn't ensure that our predictions are correct. What we are, in essence, testing are the postulates of the theory. That is to say that we use the postulates to arrive at a prediction. We then construct an experiment or contrive an observation to determine if what we observe in nature/in the lab is what we predicted. The greater the number of tests the more faith we have in the theory. And its for that reason we can have faith that black holes ranging from 5-(tens) of solar masses do exist. I was so sure that you knew all of this. I guess I was wrong. Care to comment, my friend?

When we use a theory carry out a calculation and/or make a calculation and then carry out an experiment to test the predictions and then compare the results to our predictions then the faith we have in whether the results will meet our expectations is the amount of tests that have been carried out on the theory. To use general relativity to predict only what we have evidence for kind of makes doing physics a waste of time.

We believe that the theory is correct based on the evidence gathered from testing general relativity. No theory is tested by comparing calculations of every possible equation to an experiment. We have a great deal of evidence in favor of general relativity:
http://en.wikipedia.org/wiki/Tests_of_general_relativity

In any case what leads you to make the following assertion?
Quote from: Jeff
I have come to the conclusion that 3 times the solar mass is far too small to create a viable black hole and that only masses large enough to form galactic core black holes will be stable.
Please tell me how you came to such a conclusion?

To be perfectly honest, my friend. When I see people make statements like this where the person says I have come to the conclusion... or I believe that .... when what they conclude or believe is in contradiction to a well-tested theory I find it really irritating. Do you understand why? For the most part is because the wild assumption is made and no attempt to justify it is given.

Nothing personal my friend. Just a truth about me. :)
« Last Edit: 22/04/2015 23:30:06 by PmbPhy »
 

Offline jeffreyH

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Re: Are there only galactic sized black holes?
« Reply #7 on: 22/04/2015 23:16:43 »
The problem is with the violation of the light speed limit. There is a known limit to the masses of white dwarf stars. There will be a lower mass bound to black holes, yes. I believe the current estimate to be wrong by orders of magnitude. I understand the arguments against such an idea. It has taken me almost three years to come to this conclusion. With many blind alleys along the way. I have not posted this without some careful consideration.
 

Offline PmbPhy

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Re: Are there only galactic sized black holes?
« Reply #8 on: 22/04/2015 23:39:05 »
Quote from: jeffreyH
I believe the current estimate to be wrong by orders of magnitude. I understand the arguments against such an idea. It has taken me almost three years to come to this conclusion.
But the way physics and all science works is to prove what you claim to be the case. That means to present your argument that what you say is indeed the case.

I'd like to warn you, strongly in fact, not to base your faith in a conclusion strongly on how long you've been thinking about it. For example; there was a time where I contrived an idea using multiple measurements of spin-singlet quantum states to send information FTL using quantum entanglement. I spent many years thinking this through. About 10 to be precise. It took me a very long time to realize what my mistake was and even then I had to get help from an authority on the subject. So while I'm sure that you put a lot of time into it please be careful not to use that as an argument for your belief.

To demonstrate how serious I am about this please take a look at the Crackpot Index at
http://math.ucr.edu/home/baez/crackpot.html
Quote
10 points for beginning the description of your theory by saying how long you have been working on it. (10 more for emphasizing that you worked on your own.)

Quote from: jeffreyH
With many blind alleys along the way. I have not posted this without some careful consideration.
That's a given my friend. This too is an argument that you don't want to use too much. Not that you shouldn't use it at all. After all, we do want to know that you've carefully considered it and haven't simply jumped to such conclusions. Just don't use it as part of the argument.

One more comment on your other post ... these are theoretical. You made it sound is if it was something that we know less than, say, Newton's laws of physics. Do you ever make a comment such as "But Newton's laws of physics are just theories?" No. Of course not. But for some reason, which I am yet to fathom, you made such a comment with regards to the laws of general relativity. One cannot seriously say today that black holes are merely "theoretical" or that there's "no direct evidence for them." That is simply not the case today.

Let me give you a couple of cases from special relativity (SR). SR is now accepted by the physics community. There now remains no doubt that there is anything wrong with it. It's predictions have been tested to a high degree of precision. That is not to say that there won't be any modifications to it someday. But right now we can use it with a very high degree of confidence. Time dilation is an observed fact which is tested every single day in particle accelerator labs all over the word. The derivations of many of the predictions of special relativity depend on the Lorentz contraction being precisely true. However there has never been a direct test of the Lorentz contraction so it can be said to never really have been observed. Yet we have full faith that it's correct. We no longer say "it's merely an untested prediction" (what you call "theoretical"). By the way, you used the term theoretical incorrectly. It doesn't mean what you appeared to use it to mean. But to be sure, exactly what did you mean when you said these are theoretical. Typically it means based on or calculated through theory rather than experience or practice. Is that what you meant when you used it? If so then how does it support the point that you were trying to make? Thanks.
« Last Edit: 23/04/2015 04:43:11 by PmbPhy »
 

Offline evan_au

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Re: Are there only galactic sized black holes?
« Reply #9 on: 23/04/2015 13:07:58 »
Quote from: jeffreyH
3 times the solar mass is far too small to create a viable black hole
Different respondents above have tried to work out if this comment means:
A) Natural processes cannot compress 3 solar masses into a small enough volume to create a black hole, or
B) If you did have a black hole of 3 solar masses, it would decay or disintegrate, making it non-viable, or
C) It is not possible to form a black hole of 3-30 solar masses, even in principle
D) Something else?

The comment about "violation of the light speed limit" suggests (C) to me?

Please clarify which you mean, and why would a stellar-mass black hole violate the speed of light?
 

Offline PmbPhy

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Re: Are there only galactic sized black holes?
« Reply #10 on: 23/04/2015 15:57:22 »
Quote from: jeffreyH
3 times the solar mass is far too small to create a viable black hole
Different respondents above have tried to work out if this comment means:
A) Natural processes cannot compress 3 solar masses into a small enough volume to create a black hole, or
B) If you did have a black hole of 3 solar masses, it would decay or disintegrate, making it non-viable, or
C) It is not possible to form a black hole of 3-30 solar masses, even in principle
D) Something else?

The comment about "violation of the light speed limit" suggests (C) to me?

Please clarify which you mean, and why would a stellar-mass black hole violate the speed of light?
If it's (B) then someone has a serious misunderstanding of black holes.
 

Offline jeffreyH

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Re: Are there only galactic sized black holes?
« Reply #11 on: 24/04/2015 09:37:35 »
It's not B as that would be silly. I am currently involved in birthday celebrations so have to be very brief. I will answer all comments at some point over the weekend. BTW I am not challenging relativity, only the way physics view it.
 

Offline jeffreyH

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Re: Are there only galactic sized black holes?
« Reply #12 on: 25/04/2015 17:34:55 »
My understanding is that the 3 solar mass limit has to do with the compressibility of matter, and that one must have at least that amount of mass for the gravitational field to overcome the resistance.

This limit does not take into account Hawking radiation or any other mechanisms of decomposition other than expansion into non-degenerate matter. However, my understanding is that even very small black holes would still require many billions of years (at least) to evaporate to the 3 solar mass limit. This, of course will depend on the environment as well as the black hole itself.

Why do you think only huge black holes could be stable? And what is your definition of stable?

The words viable and stable were a mistake on my part. See my response to evan.
 

Offline jeffreyH

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Re: Are there only galactic sized black holes?
« Reply #13 on: 25/04/2015 17:42:03 »
Quote from: jeffreyH
3 times the solar mass is far too small to create a viable black hole
Different respondents above have tried to work out if this comment means:
A) Natural processes cannot compress 3 solar masses into a small enough volume to create a black hole, or
B) If you did have a black hole of 3 solar masses, it would decay or disintegrate, making it non-viable, or
C) It is not possible to form a black hole of 3-30 solar masses, even in principle
D) Something else?

The comment about "violation of the light speed limit" suggests (C) to me?

Please clarify which you mean, and why would a stellar-mass black hole violate the speed of light?
If it's (B) then someone has a serious misunderstanding of black holes.

I don't have too much time at the moment to give a full response but C is the option that describes what I believe is the case. This relates to the Kerr metric and the profile of the ergosphere. You cannot relate this to the Schwarzschild metric as it has no angular momentum associated with it.
 

Offline Ethos_

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Re: Are there only galactic sized black holes?
« Reply #14 on: 25/04/2015 18:48:16 »
Quote from: jeffreyH
I believe the current estimate to be wrong by orders of magnitude. I understand the arguments against such an idea. It has taken me almost three years to come to this conclusion.
But the way physics and all science works is to prove what you claim to be the case. That means to present your argument that what you say is indeed the case.

I'd like to warn you, strongly in fact, not to base your faith in a conclusion strongly on how long you've been thinking about it. For example; there was a time where I contrived an idea using multiple measurements of spin-singlet quantum states to send information FTL using quantum entanglement. I spent many years thinking this through. About 10 to be precise. It took me a very long time to realize what my mistake was and even then I had to get help from an authority on the subject. So while I'm sure that you put a lot of time into it please be careful not to use that as an argument for your belief.

It's one thing to suggest a new idea, but quite another to claim it's valid without proper experiment and peer review. While I trust Jeffrey's instincts and sincerity, he should take heed to your warning Pete. I, as well as Jeff and yourself, have been involved in various hypothetical ideas, one of which I've spent over 15 years considering.

I'm still not ready to let the cat out of the bag. There remain unanswered questions and complications that I need help with. And even before I can ask for that educated help, I need to make it logical enough for another mind to wrap itself around.

Jeff my friend, you're one of the brightest and most inquisitive minds here at TNS. Just be careful not to jump into this too hastily. Don't expose yourself needlessly, not until you've acquired evidence through experiment and received peer review.

You may want to start by asking others here what they think about your ideas first. I'm sure Pete and several other knowledgeable folks here will offer their opinions and advice. If these intelligent members find your ideas interesting and provocative, I'm sure they will get behind you in your efforts at securing the credibility you desire.
« Last Edit: 25/04/2015 20:12:06 by Ethos_ »
 

Offline PmbPhy

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Re: Are there only galactic sized black holes?
« Reply #15 on: 26/04/2015 02:53:38 »
Quote from: Ethos_
Jeff my friend, you're one of the brightest and most inquisitive minds here at TNS. Just be careful not to jump into this too hastily. Don't expose yourself needlessly, not until you've acquired evidence through experiment and received peer review.
And, of course, I'm there for Jeff if he needs me for such a review. I strongly suggest that he talk to me in either PM in this or my own forum or in e-mail before he talks about it in public.

Quote from: Ethos_
I'm sure Pete and several other knowledgeable folks here will offer their opinions and advice.
Absolutely!

Quote from: Ethos_
  If these intelligent members find your ideas interesting and provocative, ..
Thank you, Ethos. I'm very flattered my friend.  [:I]
 

Offline evan_au

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Re: Are there only galactic sized black holes?
« Reply #16 on: 26/04/2015 12:16:54 »
Quote from: Ethos_
proper experiment and peer review
There are some experiments that are very hard to perform, like experiments on black holes*. In such cases, you have to rely on mathematics and computer simulations. Peer review can help check for errors in the mathematics and computer simulations.

Some physicists hope that the LHC may be able to produce a nuclear-sized black hole, while others think that you would need to build something much bigger than the LHC to achieve this.

*And other experiments that may be easy to perform, but probably should not, for ethical reasons...
 

Offline jeffreyH

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Re: Are there only galactic sized black holes?
« Reply #17 on: 27/04/2015 22:18:29 »
I am nothing if not open minded and this should shoot my ideas down.

http://www.nasa.gov/centers/goddard/news/topstory/2008/smallest_blackhole.html

BTW it is not actually quite as small as they think.
 

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Re: Are there only galactic sized black holes?
« Reply #17 on: 27/04/2015 22:18:29 »

 

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