Black Holes

tvanflandern
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21 years 10 months ago #4827 by tvanflandern

Reply from Tom Van Flandern was created by tvanflandern

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>[rush]: I would like to know how Meta Research receive the following article. Do you think they are really observing an "event horizon"?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

No. Several attempts have now been made to show that an "event horizon" exists. The fallacy in them is that the alternative to an event horizon is radiation redshifted to a very long wavelength. These studies do not account for that possibility.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>To me black holes does exist just on a pice of paper. It is purely theoretical but I don't know if I'm right. I'd like comments on it. Everything they find with a great radiation they claim that it comes from a black hole. I think it is just a tendencious interpretation. Am I right?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

You are correct. "Black holes" are a theoretical concept. They arise from pure math in defiance of physical principles, such as "the finite cannot become infinite". [Black holes have singularities at their centers where forces become infinite.] NASA justified the cost of the Hubble Space Telescope funding before its launch by promising Congress four things, one of which was "proof of black holes". Hence, every year near the time when Congress considers NASA's budget, we see news about the latest findings in support of black holes.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote> "come on! black holes is a part of general relativity. Are you saying Eistein was wrong?"<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

On the contrary. Einstein never accepted the possibility of black holes, and wrote a paper arguing that they could not happen. Modern black holes are an invention of Wheeler. The original concept, however, dates to the 19th century. An "ordinary" star with a very strong gravitational field so that light could not escape was called a "Mitchell star". There was no need for collapse, singularities, "event horizons", reversal of space and time, or other exotic black hole phenomena.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Well, basically is there a logic physically reason to think that there can be a body from where light can not scape or it is just fantasy?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Black holes are fantasy. But Mitchell stars might exist. The Meta Model predicts that supermassive stars might collapse to a state where gravitational shielding sets in, which would produce bodies of very high gravitational redshift. The predicted properties resemble those of a certain class of quasars. -|Tom|-

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rush
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21 years 10 months ago #4639 by rush

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<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>You are correct. "Black holes" are a theoretical concept. They arise from pure math in defiance of physical principles, such as "the finite cannot become infinite". [Black holes have singularities at their centers where forces become infinite.] NASA justified the cost of the Hubble Space Telescope funding before its launch by promising Congress four things, one of which was "proof of black holes". Hence, every year near the time when Congress considers NASA's budget, we see news about the latest findings in support of black holes.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I'm shocked.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>On the contrary. Einstein never accepted the possibility of black holes, and wrote a paper arguing that they could not happen.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Can I have access to that paper? Do you know where I can get it from internet?

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Modern black holes are an invention of Wheeler. The original concept, however, dates to the 19th century. An "ordinary" star with a very strong gravitational field so that light could not escape was called a "Mitchell star". There was no need for collapse, singularities, "event horizons", reversal of space and time, or other exotic black hole phenomena.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

That's ok. But so there can be such a massive stars that light can not scape from them? Does gravity really act on ligth?

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Black holes are fantasy. But Mitchell stars might exist. The Meta Model predicts that supermassive stars might collapse to a state where gravitational shielding sets in, which would produce bodies of very high gravitational redshift. The predicted properties resemble those of a certain class of quasars. -|Tom|-
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I did not get yet the fundamental difference between Mitchell stars and black holes... is it not that both "keep everything" inside them? There can be or there can be not a gravitational collapse?

What do you mean by "gravitational redshift"? Redshift is not just due to light lost of energy?

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tvanflandern
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21 years 10 months ago #4393 by tvanflandern

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<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>[rush]: Can I have access to that paper? Do you know where I can get it from internet?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Einstein published his papers a bit before the Internet. <img src=icon_smile.gif border=0 align=middle> But here's an excerpt from the Meta Research Bulletin about the Principles of Physics:

START EXCERPT FROM MRB --
Of course, mathematicians are unaccustomed to physical principles and are very comfortable in dealing with singularities in their equations. The mathematicians who have taken over the province of general relativity have therefore, not surprisingly, advocated the existence of real singularities in nature at the centers of “black holes”. Einstein himself, as a good physicist, never accepted the concept of black holes, and held that some new constraint would modify his equations in the future. His own words in “Annals of Mathematics”, vol. 40, #4, pp. 922-936 (October 1939, written late in his career while he was at Princeton) are illuminating, showing as they do a respect for physical principles over purely mathematical reasoning:

[AE]: “If one considers Schwarzschild’s solution of the static gravitational field of spherical symmetry …, [g44] vanishes for r=m/2. This means that a clock kept at this place would go at rate zero. Further it is easy to show that both light rays and material particles take an infinitely long time (measured in ‘coordinate time’) in order to reach the point r=m/2 when originating from a point r>m/2. In this sense the sphere r=m/2 constitutes a place where the field is singular.

“There arises the question whether it is possible to build up a field containing such singularities with the help of actual gravitating masses, or whether such regions with vanishing g44 do not exist in cases which have physical reality. …” [brief discussion of uncompressible liquids omitted]

“One is thus led to ask whether matter cannot be introduced in such a way that questionable assumptions are excluded from the very beginning. In fact this can be done by choosing, as the field-producing mass, a great number of small gravitating particles which move freely under the influence of the field produced by all of them together. This is a system resembling a spherical star cluster. … The result of the following consideration will be that it is impossible to make g44 zero anywhere, and that the total gravitating mass which may be produced by distributing particles within a given radius, always remains below a certain bound.” [core of analysis omitted; skipping to conclusions]

“The essential result of this investigation is a clear understanding as to why the ‘Schwarzschild singularities’ do not exist in physical reality. … The ‘Schwarzschild singularity’ does not appear for the reason that matter cannot be concentrated arbitrarily. And this is due to the fact that otherwise the constituting particles would reach the velocity of light.

“This investigation arose out of discussions [with Robertson and Bargmann] on the mathematical and physical significance of the Schwarzschild singularity. The problem quite naturally leads to the question, answered by this paper in the negative, as to whether physical models are capable of exhibiting such a singularity.” [End of Einstein quote]

Einstein wasn’t arguing that the Schwarzschild singularity doesn’t exist in the equations, but that it doesn’t exist in physical reality. Much as for the case of “the ultraviolet catastrophe”, he reasoned that the equations will be shown to be incomplete as observations or experiments approach that limit.
-- END EXCERPT FROM MRB

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>That's ok. But so there can be such a massive stars that light can not escape from them? Does gravity really act on light?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

That depends on the physical model chosen to go along with the math of GR. If light consists of particles, then it is reasonable that gravity acts on the particles. But if light is a pure wave, then all effects (bending, redshift, slowing) are caused by refraction in the light-carrying medium, and not (directly) by gravitational force. Of course, the light-carrying medium (same as gravitational potential field) is shaped by gravitational force so that potential obeys a 1/r density law.

If refraction if the correct mechanism, then the problem is not that light can't travel fast enough to escape, but that it refracts to infinite wavelength, making it energyless and invisible.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>I did not get yet the fundamental difference between Mitchell stars and black holes... is it not that both "keep everything" inside them? There can be or there can be not a gravitational collapse?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Presence or absence of a singularity at the center is the major difference. Absence or presence of an event horizon is another difference. Refraction vs. ballistic motion of light is another. Black holes reverse space and time inside the event horizon. Mitchell stars have more matter than they have gravity because of gravitational shielding.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>What do you mean by "gravitational redshift"? Redshift is not just due to light lost of energy?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

No, there are two dozen known redshift mechanisms. But they can be broadly divided into doppler vs. energy loss. Gravitational redshift is energy loss due to climbing out of a gravitational potential well. (Refraction produces redshift.) This effect is one of the four well-verified tests of GR. Cosmological redshift might be due to friction between light and the graviton medium, which is an unrelated way for light to lose energy. -|Tom|-

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rush
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21 years 10 months ago #4828 by rush

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Thanks a lot of your reply Tom.

I could find the Annals of Mathematics at Internet <img src=icon_smile.gif border=0 align=middle>. I have access from the University (I'm a PhD student of Geophysics. No, it has nothing to do with Astronomy <img src=icon_smile.gif border=0 align=middle>. I work with gravity but I just use Newtonian equations). I'll try to find that specific Einstein's paper and recommend that to my friends.

I wonder if big-bang cosmologists would not find a Mitchell star and then say that it is a black hole. I hope this doesn't happen. It would be too bad for Science...

PS: My English is not that good because English is not my first language <img src=icon_smile.gif border=0 align=middle>.

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