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William
2008-Jul-01, 04:10 PM
In reply to Chris Hillman’s comment:


Yah, MECO. This picture is inconsistent with gtr and there is no evidence for it and a lot against it. Dissenters should start an ATM thread (after searching for and reading older threads discussing MECO here and at Physics Forums).

Hi Chris,
I do not understand your above comment. Theoretically or observationally, what is your or others in this forums concern? I do not understand what is controversial about the MECO hypothesis. Could you please elaborate?

Your comment makes it sound as if there is overwhelming observational and theoretical evidence in support of the hairless black hole hypothesis. What do you find so convincing? What is the compelling theoretical or observational evidence for the hairless black hole hypothesis?

There are published papers that include observational data and analysis which support the assertion that that AGN and quasars have a massive magnetic field at the core of the massive object. It is asserted in those papers, that astronomical observations and analysis show the massive magnetic field at the core of AGN and quasars cannot be explained by the simple hairless black hole with an accretion disk mechanism. I do not see what there is to discuss. It is only necessary to read the papers in question. When there is observational evidence that enables one to select between the two mechanisms, what is there to discuss?

I have read through the discussion threads in the physics forums concerning the MECO hypothesis. There were no theoretical arguments presented (in the physics forums or papers) that questioned the validity of the MECO hypothesis based on physics. i.e. The MECO hypothesis is mathematically consistent with GR. The classical hairless black hole hypothesis is only one possible mathematical solution to what happens when a very massive object collapses. The MECO hypothesis unlike the hairless black hole hypothesis does not have a singularity which is a philosophical/theoretical advantage if in the real world singularities do not exist.

If there was no observational evidence to support the MECO hypothesis, we could discuss the theoretical and philosophical issues concerning singularities in a model, which is interesting. One could make the argument, as others have, that singularities in a model indicate that something is fundamentally incorrect with the model in question, as in the physical world, singularities do not exist.

William
2008-Jul-01, 05:47 PM
To provide some context for this thread the following is a comparison of the MECO massive compact object to a classical hairless black hole.

A) Similarities
Both MECO and classical hairless black hole are massive objects.
MECO can rotate. Hairless black hole can rotate.
A MECO can be charged. Hairless black hole can be charged.
MECO is theoretically consistent with general relativity. Classical hairless black hole is theoretically consistent with general relativity.

B) Differences
MECO has an intrinsic massive magnetic field. MECO does not have an event horizon.
Hairless Black hole cannot have an intrinsic magnetic field. Classical black hole theoretically has an event horizon.

AGN & Quasar Magnetic Fields
Observationally it is asserted that there is general agreement that a massive magnetic field is required to explain AGN and quasar observations.

The classical hairless black hole can only generate a magnetic field via its interaction with its accretion disk. There is currently no mechanism by which the accretion disk can generate the required massive magnetic field.

As will be shown in the next comment, detailed observations of quasars show the massive magnetic field is at the core of the quasar and has swept out that region of accretion disk. This observation and other observations support the assertion that the massive magnetic field is intrinsic to the massive compact object which is consistent with the MECO hypothesis.

http://www.google.com/search?q=Black+Hole+Accretion+Disk+Models+Lecture+ 5&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7GWYE

The following is an excerpt from a lecture on accretion disk generated magnetic fields. As others have noted there is no physical mechanism for the accretion disk to generate the massive magnetic field that is required to explain the AGN jets.


“And then the theorist raises his magic…. I mean magnetic wand… and viola, there are jets” - Shri Kulkarni

Lots of Mechanisms proposed, but most boil down to a reference to the still unsolved mechanism behind the jet mechanism for Active Galactic Nuclei (Generally the Blandford-Znajek Mechanism).

We are extrapolating from a non-working model – dangerous at best.

01101001
2008-Jul-01, 06:26 PM
I do not understand what is controversial about the MECO hypothesis.

A writer at that point might wish to ensure his readers are up to speed, or able to quickly get so, by offering a morsel of background. It may be this:
The Magnetospheric Eternally Collapsing Object (MECO) Model of Galactic Black Hole Candidates and Active Galactic Nuclei (http://adsabs.harvard.edu/abs/2006astro.ph..2453R) (Abstract).

One of the Physics Forums topics might be: MECO - has it got legs? (http://www.physicsforums.com/showthread.php?t=123963)

Chris Hillman
2008-Jul-01, 07:16 PM
[EDIT: thanks to the moderator who moved this thread to ATM while I was writing this post! And wow, that was fast work! :Smile: ]

Like "plasma cosmology", "MECO" is a catchphrase which can denote a variety of claims, some simply cranky, others not particularly objectionable. It is important to distinguish between three types of claims which have been made by MECO proponents:

some astrophysical black hole candidates may be some other kind of object, which can be recognized by possesing a nonzero magnetic moment,
allegedly, black holes do not exist in Nature at all; all known "black hole candidates" are allegedly actually some other kind of object, e.g. MECOs; gravitational collapse is allegedly forbidden in Nature by gtr plus further physical considerations,
gravitational collapse is allegedly not a prediction of gtr at all [sic]; ordinary objects allegedly cannot fall into a black hole, e.g. one modeled by the Schwarzschild vacuum "because" the tangent vector to any infalling timelike curve allegedly becomes a null vector [sic]; the textbook analysis of the Schwarzschild vacuum solution is allegedly "wrong" [sic].

The first suggestion would not be regarded as cranky, although it is not yet generally accepted that MECOs have been spotted in Nature. The second claim is highly controversial and theoretically dubious for many reasons; few astrophysicists would agree that this claim currently enjoys observational support; to the contrary, there is much evidence against it. The third claim is provably wrong as a statement about gtr, and can only be characterized as cranky.

Some papers surveying observational evidence bearing on the objects generally known as black holes :wink: are
http://arxiv.org/abs/astro-ph/0701228
http://arxiv.org/abs/astro-ph/0310692
http://arxiv.org/abs/astro-ph/9912186
http://arxiv.org/abs/astro-ph/9710352
A very nice expository article on the basics of black holes is
http://arxiv.org/abs/astro-ph/9801252
Enjoy! :Smile:

For those of you who wish to debate the merits of MECO, the relevant arXiv eprints advocating MECO are mostly listed here:
http://arxiv.org/find/gr-qc/1/au:+Mitra_Abhas/0/1/0/all/0/1
http://arxiv.org/find/astro-ph/1/au:+Leiter_D/0/1/0/all/0/1
Please note that if you click on individual eprints, you'll be sent to an abstract page, which includes links to citations of the eprint in question, according to SPIRES and other sources. Chasing these down, anyone experienced in the physics literature will be able to verify my statement that MECO is certainly not regarded as mainstream (recent reviews I have seen do not even mention it as a viable alternative to the standard notion of black holes).

I myself won't participate (been there, done that), since (referring my list of three distinct types of claim):

the first type of claim is not yet accepted, but I wouldn't call it inherently ATM given the current state of knowledge,
the second type of claim is adequately addressed by review papers such as the ones I cited, and references therein, since these explain why most astrophysicists feel that available evidence strongly supports the notion that black holes (event horizons and all!) exist in nature (and are in fact rather common objects),
as I am concerned, I and others adequately debunked the third type of claim many years ago (in any case, it's an easy student excercise to check that the textbooks are not in fact wrong).


[EDIT: it might help to point out that "hair" is generally used in the research literature on gravitation physics to refer to "charges" which an object might have, in addition to mass and electrical charge. These can include hypothetical "charges" arising from hypothetical fields of various kinds. In gtr, the no hair theorems assert, roughly speaking, that a black hole is entirely characterized by its mass, electrical charge, and "spin" (intrinsic angular momentum). See the monograph by Frolov and Novikov, Black Hole Physics, for details. It may also help to know a bit about effective field theory; see the review paper at Living Reviews in Relativity (http://relativity.livingreviews.org/), an excellent collections of regularly updated research level survey papers on gravitation physics.]

Have fun with it!

William
2008-Jul-01, 07:44 PM
The following is published observation data that supports the existence of an intrinsic magnetic moment inside of the central compact within Quasar Q0957.

http://www.iop.org/EJ/article/1538-3881/132/1/420/204784.text.html


Observations Supporting the Existence of an Intrinsic Magnetic Moment inside of the Central Compact Object within Quasar Q0957+561 by Rudolph E. Schild, Darryl Leiter, and Stanley Robertson

Picture of magnetic propeller at quasar core.

http://www.iop.org/EJ/article/1538-3881/132/1/420/204784.fg1.html

Definitive observational evidence to determine whether Quasar Q0957 has a hairless black hole at its core or a MECO?

Black Hole or MECO? Decided by a Thin Luminous Ring Structure Deep Within Quasar Q0957 by Rudolph E. Schild, Darryl J. Leiter

http://arxiv.org/abs/0806.1748v1


Optical, Infrared, X-ray, and radio wavelength studies of quasars are beginning to define the luminous quasar structure from techniques of reverberation and microlensing. An important result is that the inner quasar structure of the first identified gravitational lens, Q0957+561 A,B seems not to show the kind of structure expected for a supermassive black hole, but instead show a clean-swept interior region as due to the action of a magnetic propeller, just as expected for a MECO (Magnetic Eternally Collapsing Object) structure. Given the present state of the observations, the strongest model discriminant seems to be the existence of a thin luminous band around the inner edge of the accretion disc, at a distant radius approx. 70RG from the approx. 4×10^9 m⊙ central object. Since the existence of a clean magnetic propeller swept inner region approx. 70 RG surrounded by a sharp approx. 1 RG disc edge are the low-hard state spectral properties associated with a highly redshifted central MECO object, we are led to the conclusion that these observations imply that the Q0957 quasar contains a central supermassive MECO instead of a black hole.

William
2008-Jul-01, 08:18 PM
In reply to Chris Hillman comment:


I won't participate since as far as I am concerned, I and others have already debunked numerous claims made by MECO proponents.

Chris,
You misunderstand the subject of this thread. This thread is entitled “Do Hairless Black Holes Exist?” There is strong observational evidence that supports the MECO hypothesis over the hairless black hole hypothesis. The MECO hypothesis is mainstream astrophysics.

You have made strong statements against the MECO hypothesis which appear to be unfounded. Please provide support for your statements. Astrophysics is an observational based science. It appears a hairless black hole cannot explain the observations. I am offering you an opportunity to explain your strong statements. Also you have inferred that others have provided definitive theoretical analysis that "debunks" the MECO hypothesis. Please provide support for that statement.

As noted above observational evidence shows the quasar central compact object has a massive magnetic field at its core. As noted above the massive magnetic field has swept clean the core region of the quasar, so there is no alternative explanation (as there is no gas or ions in the region) for the strong magnetic field but a MECO.

William
2008-Jul-01, 09:44 PM
I am waiting for someone to provide theoretical evidence (published paper) that refutes the MECO hypothesis on theoretical grounds or a published paper that provides observational evidence that supports a hairless black hole over a MECO.

Here is a published paper in a physics journal that provides theoretical support for the MECO assertion that hairless black holes cannot form.

Does The Principle Of Equivalence Prevent Trapped Surfaces From Being Formed In The General Relativistic Collapse Process?

http://adsabs.harvard.edu/abs/2001astro.ph.11421L

Here is a paper by a general relativity specialist that provides theoretical support for an eternal collapsing massive object rather than a hairless black hole.

On the Final State of Spherical Gravitational Collapse, by Abhas Mitra

http://www.ingentaconnect.com/content/klu/fopl/2002/00000015/00000005/00456814

This is another published paper that provides spectral analysis that supports the MECO hypothesis.

http://arxiv.org/PS_cache/astro-ph/pdf/0402/0402445v1.pdf

On the Origin of the Universal Radio-X-Ray Luminosity Correlation In Black Hole

Here is another published paper that provides observational and theoretical evidence to support the MECO hypothesis.

On Intrinsic Magnetic Moments in Black Hole Candidates by Stanley Robertson and Darryl Leiter

http://www.journals.uchicago.edu/doi/pdf/10.1086/379602?cookieSet=1

William
2008-Jul-02, 01:29 AM
The equations presented in GR text books concerning black holes ignored the physics and mathematical issues of the transition from massive object to singularity. The following is a review paper presented at a general relativity conference in 2004 which notes, the theoretical and physical solution to what happens when a super massive object collapses is not known as there is no quantum gravitational theory and the original General Relativity proposed solutions to the super massive object collapse ignored the crucial and unavoidable step that explains how the massive object changes to a singularity.

The MECO hypothesis is that the massive object never reaches a singularity. Quantum effects create a massive magnetic field which creates electron/positron pairs that stops the collapse of the massive object. Observationally that is what is observed.

On Gravitational Collapse in Spherical Symmetry by Fabio Giannoni

http://www2.mate.polimi.it/convegni/viewpaper.php?id=42&cf=6


The questions connected with the study of gravitational collapse in General Relativity are far from being solved in a satisfactory manner. Many models providing counter examples to Penrose’s conjecture have been found, and …


In addition, whenever one will be to give satisfactory answers in more general cases, one must keep in mind that not only classical Relativity should be taken into account, since quantum effects may not be neglected in the extreme states of collapse, but unfortunately again, quantum gravity is still an unknown theory…


These are the main reasons why Penrose’s opinion about the questions of naked singularities existence in Nature, termed almost forty years ago as “the most fundamental unanswered questions, of general relativistic collapse theory", is still of great interest at present time.

A second but interesting question is why was the myth of a singularity, the hairless black hole solution perpetuated? This question is particularly relevant now that there is definitive observational evidence that confirms hairless black holes do not exist.

“Black Holes or Eternally Collapsing Objects: A Review of 90 Years of Misconceptions” by Abhas Mitras

http://adsabs.harvard.edu/abs/2006fbhr.book....1M

William
2008-Jul-02, 03:22 AM
The following is a link to an abridged version of Abhas Mitra’s paper that started the MECO theoretical line of thought. As Mitra notes in his paper, an eternally collapsing solution to the spherical gravitational collapse of a massive object is both mathematically correct within General Relativity and avoids creating a singularity.

I believe Mitra’s solution is a general solution to the massive object collapse within General Relativity. The MECO solution is a specific solution which is consistent with Mitra's generalized solution and also is in agreement with observations. Mitra was able to get this paper published. The reviewers of Mitra's paper noted Mitra’s solution is mathematically correct and in agreement with General Relativity.

I could find no reference to MECO or to spherical gravitation collapse that refuted the MECO hypothesis or Mitra’s generalized solution.

As noted above there are other published papers by other authors that theoretically support the assertion that an event horizon does not form.

“Non-occurrence of trapped surfaces and Black Holes in spherical gravitational collapse:”An abridged version by Abhas Mitra


http://nsdl.org/resource/2200/20061006191352475T


We have shown in that for arbitrary eternally collapsing EOS and radiation transport properties, (even) the idealized spherical gravitational collapse DOES NOT lead to the formation of trapped surfaces: 2GM(r,t)/R <=1. Hence all singularity theorems of Hawking, Penrose and Geroch, built on the assumption of formation of trapped surfaces, get invalidated! And this inequality, demands that M->0 if indeed R->0. We have shown that the final state corresponds to a zero mass BH state and, this state would occur only after infinite proper time indicating that GR is indeed the only naturally singularity free theory for isolated bodies (as was cherished by Einstein). This M->0 state would materialize after the body radiates its entire initial mass-energy.


Thus there is no event horizon at any finite R or M, and, therefore all the great theoretical confusions like whether there could be (i) White Holes, (ii) whether t (R) becomes spacelike (timelike) inside the EH (iii) Loss of information in gravitational collapse, and (iv) validity of cosmic censorship conjecture get resolved. At any finite proper time, the collapsed object would be either static (z<2) or may appear static (R almost frozen) though, in extreme cases, internally, in terms of proper radial length, it might be collapsing at a speed ~c! We call the latter as Eternally Collapsing Objects.

William
2008-Jul-03, 02:16 AM
As noted below, no General Relativity specialist has contradicted Abhas Mitra’s theoretical result that a Black Hole event horizon does not form, that its hypothesized existence has due to a theoretical error, in solving the GR equations. As noted below Hawking in a conference in 2004 admitted that what forms when a massive object collapses is not a black hole “in the absolute sense”. Hawking’s “new” black holes appear to take an infinite amount of time to collapse, which is exactly what Abhas Mitra’s paper stated.

http://us.rediff.com/news/2004/aug/03hole.htm

Theoretically Mitra’s solution to a massive compact object collapse shows that the collapsing body takes an infinite amount of time to collapse and hence does not form a singularity. The classical solution to black hole collapse had a singularity which was one indication it was not the correct solution.

It should also be noted that observation of magnetic propellers in quasar's cores provides very strong observational support in favour of Mitra’s solution, as if the black hole had an event horizon, it would be hairless.


The following is an excerpt from Wikipedia that discusses the well known fact that the classic black hole solution, which allows an event horizon also allows singularity to form. As noted above Hawking now appears support the existence of a “new” black which does not collapse in the absolute sense and hence does not create singularity.

Singularity

According to general relativity (my comment, According to the solution of GR which Mitra's paper states is not correct), a black hole's mass is entirely compressed into a region with zero volume, which means its density and gravitational pull are infinite, and so is the curvature of space-time that it causes. These infinite values cause most physical equations, including those of general relativity, to stop working at the center of a black hole. So physicists call the zero-volume, infinitely dense region at the center of a black hole a singularity.



The singularity in a non-rotating black hole is a point, in other words it has zero length, width, and height. The singularity of a rotating black hole is smeared out to form a ring shape lying in the plane of rotation. The ring still has no thickness and hence no volume.


The appearance of singularities in general relativity is commonly perceived as signaling the breakdown of the theory. This breakdown is not unexpected, as it occurs in a situation where quantum mechanical effects should become important, since densities are high and particle interactions should thus play a role. Unfortunately, to date it has not been possible to combine quantum and gravitation effects in a single theory. It is however quite generally expected that a theory of quantum gravity will feature black holes without singularities.

The appearance of singularities in general relativity is commonly perceived as signaling the breakdown of the theory. This breakdown is not unexpected, as it occurs in a situation where quantum mechanical effects should become important, since densities are high and particle interactions should thus play a role. Unfortunately, to date it has not been possible to combine quantum and gravitation effects in a single theory. It is however quite generally expected that a theory of quantum gravity will feature black holes without singularities.

William
2008-Jul-04, 04:51 AM
Abhas Mitra’s first paper which was published in 2000 presented a theoretical argument that showed why an event horizon cannot form when a massive object collapses. Mitra stated in his paper, that theoretical solutions to the problem of a massive object collapse had ignored mathematical and physical issues within their proposed solutions. (i.e. They jumped to a theoretically state which cannot be reached by a real physical object that is collapsing.)

Mitra’s first paper presented a detailed corrected solution to the problem of a the collapse of a massive object written for general relativity specialists. This paper published in 2006 is one of series of papers that he has published and presented at conferences that is written for the general physics and astrophysics community.

This is a link to the paper preprint and a couple of excerpts that explain the core of his theory and one of the logic paradoxes which his solution resolved.

http://arxiv.org/abs/astro-ph/0608178


There have been some recent developments in the study of GR gravitational collapse which show that GR collapse time scale is indeed determined by the Einstein-Eddington time scale developed above. Note that the massive objects tend to collapse inexorably to Black Holes (BH) having an Event Horizon (EH) with z = ∞. If so, the object must pass through states having arbitrarily large but finite z states to reach the z = ∞ state. It has been shown that as the object would become more and more compact (i.e., z would increase), the object would become radiation energy dominated, ρr ≫ ρ0 (Mitra 2006a). ….


…Initially, of course, the value of α ≪ 1. But as z → ∞ during the BH formation, the value of α starts increasing dramatically ∼ (1 + z). Sooner or later, at an appropriate range of finite value of z, one must attain a state α ≈ 1 when the outward radiation flux would attain its critical “Eddington value”. By the very definition of an “Eddington luminosity”, catastrophic collapse would then degenerate into a secular quasistatic contraction supported by radiation pressure (Mitra & Glendenning 2006).


On the other hand, if there would be objects with appropriately large z ≫ 1, one will have an RPSS at arbitrary low or high value of M because in such a case, ρr >> ρ0 as z ≫1 (Mitra 2006b). In other words, during continued collapse, the collapsing object first becomes an extremely relativistic (z ≫ 1) RPSS before becoming a true BH with (z = ∞). Then as explained by Eq.(37), as the RPSS tends to become a true BH with z → ∞, the lifetime of the PRSS phase becomes infinite: umin EE = 5 × 108 (1 + z) yr → ∞ (41) Hence such objects have been termed as “Eternally Collapsing Objects” (ECO) (Mitra 1998b, Mitra 2000, Mitra 2002a,b, Mitra 2006b,c,d,e,f,g,h, Mitra & Glendenning 2006). Any astrophysical plasma is always endowed with microscopic currents and some intrinsic magnetic field (B). When such a plasma contracts, in a crude picture, its magnetic field gets compressed as B ∼ R−20 . And this is the basic reason that a compact Neutron Star has strong intrinsic magnetic field.


The following is one of a number of logical arguments that Mitra presents in his paper to justify the assertion that an classical black hole event horizon cannot form.


Special relativity theory is founded on the principle “nothing can move faster than light” (actually faster than a certain limiting speed). GTR asserts that this principle is valid even in curved spacetime, in the presence of gravity, for an observer with arbitrary acceleration. It is known for long that if a test particle would approach the EH, its 3-speed would approach the speed of light, v → c and in fact, if one uses the so-called Schwarzschild coordinates, one has v = c on the EH (Mitra 2000, 2002a,b). If the BH would have, M > 0, Rg > 0, one would, in this case, have v = c at R = Rg > 0. If so, the speed of the particle inside the EH would exceed the speed of light, v > c. Many GR “experts” try to fudge this real fundamental problem by insisting that, in suitable coordinates, one may have vEH < c. This is actually impossible if the physics would be treated self-consistently because, STR velocity addition law ensures that once v → c w.r.t. a certain observer, it must be so w.r.t. any other observer. Thus, at best one may assume that v → c asymptotically without ever exceeding it. This would be possible only if M = 0 and proper time to approach the EH, τ → ∞. (Mitra 2000, Mitra 2002a,b). In technical parlance, existence of a finite mass BH would violate the condition that the worldline of the infalling particle must be timelike (Mitra 2000, 2000a,b, Leiter & Robertson 2003).

William
2008-Jul-04, 12:18 PM
There have been papers published which assert that indirect evidence for the existence of an event horizon (An event horizon is a theoretical component of the hairless black hole hypothesis. There is theoretically a singularity hidden by the event horizon, in the hairless black hole hypothesis.) is the fact that quasars and black hole candidates do not emit hard type 1 x-rays. While it is observationally correct that black holes candidates do not emit hard type 1 x-rays, that observation is consistent with the eternally collapsing MECO hypothesis as the MECO does not have a hard surface. The fact that type 1 x-rays are not observed cannot therefore be used to determine which hypothesis is correct, the MECO or Hairless Black hole.

The observation and issue that can be used to determine which of the two hypotheses is correct - the hairless black hole hypothesis as opposed to the MECO hypothesis - is the need to explain the ubiquitous massive magnetic fields that has been observed at the centre of quasars, AGN, and black hole candidates. The hairless black hole mechanism/hypothesis has an “event horizon” which does not allow the massive object to have a magnetic field.

There is no theoretical explanation as to how a hairless black hole could create a massive magnetic hole. The event horizon, makes it not possible for the hairless black hole mechanism to create a massive magnetic field.

Comment:
Quasars/AGN specialists have collectively moved toward accepting the assertion that a massive magnetic field is required to create the quasar and AGN jets. There is also direct observational evidence of a very strong magnetic field at the core of quasars, AGNs, and black hole candidates. The MECO hypothesis and mechanism explains how and why the massive magnetic fields are generated.

This paper by Abhas Mitra published in 2006 discusses what can be concluded from the fact that type 1 x-rays are not observed and discusses the magnetic field issue.


http://adsabs.harvard.edu/abs/2006AdSpR..38.2917M

"On the non-occurrence of Type I X-ray bursts from the black hole candidates"



It has been justifiably questioned if the black hole candidates (BHCs) have “hard surface” why Type I X-ray bursts are not seen from them [Narayan, R., Black holes in astrophysics, New J. Phys, 7, 199 218, 2005]. It is pointed out that a “physical surface” need not always be “hard” and could be “gaseous” in case the compact object is sufficiently hot [Mitra, A., The day of the reckoning: the value of the integration constant in the vacuum Schwarzschild solution, physics/0504076, p1 p6, 2005; Mitra, A., BHs or ECOs: A review of 90 years of misconceptions, in: Focus on Black Holes Research, Nova Science Pub., NY, p1 p94, 2005]. Even if a “hard surface” would be there, presence of strong intrinsic magnetic field could inhibit Type I X-ray burst from a compact object as is the case for Her X-1. Thus, non-occurrence of Type I bursts actually rules out those alternatives of BHs which are either non-magnetized or cold and, hence, is no evidence for existence of Event Horizons (EHs). On the other hand, from the first principle, we again show that the BHCs being uncharged and having finite masses cannot be BHs, because uncharged BHs have a unique mass M = 0. Thus the previous results that the so-called BHCs are actually extremely hot, ultramagnetized, Magnetospheric Eternally Collapsing Objects (ECOs) [Robertson, S., Leiter, D., Evidence for intrinsic magnetic moment in black hole candidates, Astrophys. J., 565, 447 451, (astro-ph/0102381), 2002 ; Robertson, S., Leiter, D., MECO model of galactic black hole candidates and active galactic nuclei, in: New Developments in Black Hole Research, Nova Science Pub., NY, p1 p44, astro-ph/0602453, 2005] rather than anything else get reconfirmed by non-occurrence of Type I X-ray bursts in BHCs.


This excerpt from the same paper, discusses the issue of the black hole candidate jets.



There could be circumstantial evidences that the Black hole Candidates (BHCs) are not Black holes (BHs): (1) Many BHCs do exhibit occurrence of ultra-relativistic jets, and, though no event horizon has ever been detected, it was generally believed that somehow mysteriously and self-contradictly, such jets must be associated with event horizons (when “nothing can escape from an event horizon”). However, the compact object in Cir X-1, has a physical surface and has been found to launch an ultra relativistic jet with bulk Tau > 10 (Fender et al., 2004). Similarly, all ultrarelativistic jets may actually be associated with compact objects having physical surfaces. In general, presence of an intrinsic magnetic field may be necessary for both launching and collimation of jets. In fact, we know with certainty that there are objects without any event horizon but intrinsic magnetic field; and often they do launch jets: e.g., protostellar clouds, stars, Neutron Stars etc. In contrast, not a single case is known with certainty, where an object with an event horizon and without any intrinsic magnetic field has ever launched a jet because an event horizon has never been be detected! (2) As discussed (Van der Klis, 2006), the essential low freq. QPO behaviour of neutron stars’ and BHCs is the same. The difference in the high freq. range may be due to stronger B and z of BHCs. (3) The large kick velocities associated with BHC binaries cannot be explained if the BHCs are really BHs which are formed by direct gravitational collapse(Van den Heuvel, 2006) because prompt formation of finite mass BH is supposed to be a quiet affair accompanied by the prompt formation of an event horizon . On the other hand, such large kick velocities can be easily understood if the BHCs are objects with physical surfaces (but HOT) and formed in events similar to powerful supernovae (Gamma Ray Bursts) whose luminosity could be 100 times more than for typical SN events.

William
2008-Jul-04, 03:34 PM
There have been comments by notable physicists that the hairless black hole solution does not make physical sense. One complaint is that a singularity cannot form in nature. As noted below both Einstein and Eddington looked for other general relativity solutions to the problem of a collapsing mass which did not have a singularity. Physicists at the time accepted a singularity in the hairless black hole solution, because there was no alternative solution. There have been as noted above a number of different criticisms for the hairless black hole solution, one of which is conservation of energy.

The MECO solution is consistent with general relativity, it does not produce a singularity, and it is consistent with basic physics such as the conservation of energy. The hairless black hole solution can only be reached by theoretically jumping to the final ‘black hole hairless state’. As Abhas Mitra shows in the attached paper, if the self gravitational energy of the object is taken into account the collapsing object reaches equilibrium as a high red shifted ball of radiation energy and mass, not a hairless black hole with an event horizon that covers a singularity.

http://arxiv.org/abs/astro-ph/0608178

“Sources of Stellar Energy, Einstein- Eddington Timescale of Gravitational Contraction and Eternally Collapsing Objects” by Abhas Mitra


Recently, it has been shown that the during the final stages of BH formation (z ≫ 1), the collapsing object would be dominated by radiation energy rather than by rest mass energy density (Mitra 2006a). For such a self-gravitating ball of radiation, the luminosity would indeed be maximal, i.e., L → Led or α ≈ 1. Consequently, the observed duration of such final stages would indeed be determined by Einstein -Eddington time scale as obtained in this paper (Mitra 2006b, Leiter & Robertson 2003, Mitra & Glendenning 2006). The fundamental reason that both the observed Einstein Eddington time scale as well as the comoving proper time scale for formation of the eventual zero mass BH is infinite is that trapped surfaces are not allowed in collapse of isolated bodies and, atleast for isolated bodies, GR is a singularity free theory even at the classical non -quantum level as cherished by its founder Einstein. The physical reason for the non-occurrence of both trapped surfaces and finite mass BHs is the same relativistic adage “nothing can move faster than light”. One cannot but recall at this juncture that Einstein (1939) too attempted to disprove the existence of BHs by using the same adage. However he failed to properly recognize that the vacuum Schwarzschild (actually Hilbert) solution indeed suggests formation of unique zero mass BHs. On the other hand, since he tried to be aloof towards both the implications of this important solution and also the exact OS solution, his attempted disapproval of BH looked inconsistent and suspicious. Many BH/singularity “experts” of present epoch however take unkind advantage of this situation and often try to portray Einstein as a scientist who lacked sufficient appreciation of GR (Baez & Hillman 2000):


• Einstein’s physical intuition about non-existence of (finite mass) BHs was correct though he could not see (zero mass) BHs as the asymptotical solutions of physical continued gravitational collapse of a chargeless fluid. However, with regard, to a point particle possessing a charge, Einstein & Rosen (1935) wrote that

“ It also turns out that for the removal of the singularity it is not necessary to take the ponderable mass m positive. In fact, as we shall show immediately, there exists a solution free from singularities for which the mass constant m vanishes. Because we believe that these massless solutions are the physically important ones we will consider here the case m = 0” (emphasis is due to the author).



• Despite Eddington’s unjustified public denouncement of Chandrasekhar’s
correct result on upper limit of cold self-gravitating objects, Eddington’s physical intuition and insight were far superior to that of Chandrasekhar; he was the first to correctly visualize the unphysical Nature of (finite mass) BHs and insisted that “I think there should be a law of nature to prevent a star from behaving in this absurd way” And as emphasized by Mitra (2006b) and Mitra & Glendenning (2006), this “law of Nature” is nothing but the bending of radiation due to strong selfgravity and consequent attainment of a critical Eddington luminosity. Of course, at that time, Eddington too failed to recognize that the gravitational contraction process must be radiative and a BH (with M = 0) should indeed be the asymptotical solution of the continued collapse process. It would be recognized much later that Chandrasekhar’s result about upper limit of cold objects was almost universally misinterpreted, most notably by Chandrasekhar himself, as an upper limit on mass of all compact objects, hot or cold. Thus it would be recognized that Chandrasekhar’s discovery had a profound retrograde effect on the development of the physical theory of continued gravitational collapse and relativistic astrophysics in general. Probably this misinterpretation along with the misinterpretation that the OS collapse was physical and suggested formation of finite mass BHs (when in reality, there is no collapse without finite pressure and heat flux, or, mathematically, M = 0 in such a case), put the clock back by 60 years as far as the question of the final state of continued collapse is concerned.

William
2008-Jul-04, 07:47 PM
To disprove the classic hairless black hole solution as to the scientific problem of what happens when a massive body collapses the physicist Abhas Mitra first wrote a series of published papers (first paper was published in 1999.) that outlined logical errors in the mathematical and physical assumptions that were used to derive the hairless black hole solution. Other authors in published articles brought up the same criticisms as Mitra, however, they did not have an alternative general relativity solution to the scientific problem of “what happens when a massive body collapses?”

The following is a simpler logical argument that Mitra presents to show that a massive object when it collapses forms an eternally collapsing body, rather than a classical hairless black hole.

In this paper which was published in 2006, Mitra shows how if the redshift of the massive collapsing object is not ignored in the collapse calculation, that the redshift of the collapsing body will and should increase as collapsing body becomes hotter. As the body collapses and becomes hotter, Mitra asserts, there is no limit to the mass that can be radiation support at high z. The resultant is a highly redshift eternally collapsing object rather rather than a hairless black hole that theoretical has an event horizon and a singularity.

Comment:
I have not seen any discussion of this simple redshift argument in the physics forums. As stated above I could not find a single paper published paper that refutes Mitra’s denunciation of the classical hairless black hole solution. I could not find any published criticism of the MECO solution to the massive object collapse problem on theoretical grounds. Mitra has responded to all reviewers comments and questions to get his paper published.

http://arxiv.org/abs/gr-qc/0603055

“Radiation Pressure Supported Stars in Einstein Gravity: Eternally Collapsing Objects” by Abhas Mitra


Even when we consider Newtonian stars, i.e., stars with surface gravitational redshift, z ≪ 1, it is well known that, theoretically, it is possible to have stars, supported against self-gravity, almost entirely by radiation pressure. However, such Newtonian stars must necessarily be supermassive(Hoyle and Fowler 1963; Fowler 1966;Weinberg 1972). We point out that this requirement for excessive large M in Newtonian case, is a consequence of the occurrence of low z ≪ 1. But if we remove such restrictions, and allow for possible occurrence of highly general relativistic regime, z ≫ 1, we show that, it is possible to have radiation pressure supported stars at arbitrary value of M. Since radiation pressure supported stars necessarily radiate at the Eddington limit, in Einstein gravity, they are never in strict hydrodynamical equilibrium. Further, it is believed that sufficiently massive or dense objects undergo continued gravitational collapse to the Black Hole stage characterized by z = ∞. Thus, late stages of Black Hole formation, by definition, will have, z ≫ 1, and hence would be examples of quasistable general relativistic radiation pressure supported stars (Mitra 2006). It is shown that the observed duration of such Eddington limited radiation pressure dominates states is t ≈ 5 × 10^8(1 + z) yr. Thus, t → ∞ as Black Hole formation (z → ∞) would take place. Consequently, such radiation pressure dominated extreme general relativistic stars become Eternally Collapsing Objects (ECOs) and the BH state is preceded by such an ECO phase. This result is also supported by our previous finding that trapped surfaces are not formed in gravitational collapse(Mitra1 2005) and the value of the integration constant in the vacuum Schwarzschild solution is zero(Mitra2 2005). Hence the supposed observed BHs are actually ECOs.

publius
2008-Jul-05, 12:24 AM
William,

You've presented a lot of MECO material here that has gone unchallenged, and that's primarily because this all involves a very complex subject, General Relativity, that many BAUT members here aren't versed in enough to feel to qualified to discuss it.

However, the MECO idea is very controvesial to say the least and is far from any mainstream notion. The three main proponents of MECO/ECO are Abhas Mitra, Stanley Robertson, and Darryl Leiter. A search of the Arxiv will turn up some of their papers there:

Mitra:
http://arxiv.org/find/astro-ph/1/au:+Mitra_A/0/1/0/all/0/1

Robertson:
http://arxiv.org/find/astro-ph/1/au:+Robertson_S/0/1/0/all/0/1

Leiter:

http://arxiv.org/find/astro-ph/1/au:+Leiter_D/0/1/0/all/0/1

Take a look at these, and then note the Citebase history. You'll see this is mostly a tight group that just cites and quotes themselves.

I was vaguely with the familiar with the MECO/ECO idea which I thought was "black holes can't really form in nature", due to something about radiation pressure of gravitationally bound radiation. That is, the thing would not collapse to a singularity in its own proper time.

However, I recently learned that the MECO/ECO proponents are basing all this on some pretty dubious, fairly nonsensical notions:

They actually argue that the Schwarzschild vacuum itself is flawed, by some argument that the "horizon is really a point, not a spherical surface", and is a true, essential singularity, and not a coordinate one and somehow that implies the total mass M must be 0. They go on to state that nothing could actually fall into a *pre-existing* Schwarzschild black hole in its own proper time.

The latter argument is based on an erroneous claim that the world lines of infalling test particles would become null (light-like) at the horizon. Their argument against the Oppenheimer "cold dust collapse" is also based on the claim that world lines of the collapsing dust particles would become null.

http://arxiv.org/abs/astro-ph/0111421

All of this is just frankly flat out wrong -- even I can appreciate that.

[continued in a bit]

-Richard

publius
2008-Jul-05, 12:54 AM
Two of these "Schwarzschild is wrong" papers, on which Mitra and others base their notions are these:

http://arxiv.org/abs/gr-qc/0102055

http://arxiv.org/abs/physics/0310104

by Abrams and Antonci respectively.

Again, I can't really make sense of what is being claimed other than Schwarzschild is really wrong, it was David Hilbert's error, and what we all know as the Schwarzschild metric today wasn't really Schwarzschild's but is Hilbert's error. [Which reminds me of similiar claims by ATM EM types like Thomas Bearden that Heaviside (see avatar) corrupted Maxwell's original work. :) ]

There's something in there that the radial Schwarzschild (Hilbert?) coordinate 'r' should be replaced by 'r - 2m' (in geometric units) and somehow this shows the horizon is "really a singular point" or something like that.

And apparently that goes back to an error made by mathematician Marcel Brillouin way back in 1923 before things were fully worked out and understood. Much of the modern machinery of GR and differential geometry came later, after painstaking work. Before that things weren't as well understood as they are now.

At any rate, Steve Carlip, an expert in GR, who should be familiar to many BAUTers (I've used one of his papers as the reference for the many "speed of gravity" questions that pop up here), had this to say in a post to sci.physics.research about these papers:



From: Steve Carlip (UC Davis)
Date: 11.04.06, 15:36
Group: sci.physics.research

LEJ Brouwer <intuitionist1@yahoo.com> wrote:
[...]

> The reason I am interested is because the following papers claim that
> there is an error in the interpretation of the radial coordinate 'r' in
> the standard Schwarzschild metric:

> L. S. Abrams, "Black holes: The legacy of Hilbert's error", Can. J.
> Phys. 23 (1923) 43, http://arxiv.org/abs/gr-qc/0102055

> S. Antoci, "David Hilbert and the origin of the 'Schwarzschild
> solution'", http://arxiv.org/abs/physics/0310104

> S. J. Crothers, "On the general solution to Einstein's vacuum field and
> its implications for relativistic degeneracy", Prog. Phys. 1 (2006)
> 68-73.

> In particular they show, in a rather simple fashion, that the event
> horizon is at radius zero, coinciding with the position the point mass
> itself, and actually appears pointlike to an external observer.

These papers are complete nonsense. In particular, the authors seem
not to understand the basic fact that physics does not depend on what
coordinates one chooses to use.

It is trivially true that if one changes coordinates in the standard
Schwarzschild solution from r to r-2m, then the horizon is at r=0.
It is also trivially true that this does not change the spacetime
geometry -- the horizon is still a lightlike surface, with an area at
fixed time of 4m^2. Choosing a coordinate that makes the horizon
look like a point doesn't make it a point -- it just means that you've
made a dumb coordinate choice.

> They claim that the reason that the original misinterpretation occurred
> is because Hilbert incorrectly assumed a priori that the 'r' which
> appears in the metric must be the radial coordinate (in fact, it need
> only parametrise the radii to ensure a spherically symmetric solution).

It is radial in the sense that the set of points at constant r and t
is a two-sphere of area 4pi r^2. It is not "radial distance," but
no one has claimed that it is.

> The careful analysis of Abrams et al shows that the point mass actually
> resides at r=2m, which therefore corresponds to the true origin, so
> that there is in fact no 'interior' solution.

This analysis is not "careful" -- it's mathematically awful. How can
a "point mass" reside at a two-sphere of finite area? What sense does
it make to say that a mass resides at a position at which the Ricci
tensor is zero?

Abrams makes an elementary mistake. He concludes that r=2m (in standard
Schwarzschild coordinates) is singular because the "radius" of a circle
around this "point" goes to zero as r->2m while its "circumference"
does not. But this is not a singularity -- it's just a reflection
of the fact that r=2m is a two-sphere, not a point.

> If the event horizon is at the origin, and there is no interior
> solution, then this tends to raise the question, "well, where does a
> radially infalling particle actually go?". Does it just bounce off the
> 'brick wall' (or rather, 'brick point')?

To answer this, you just compute the motion. You find that it falls
right past the "origin," with nothing peculiar happening there. (Of
course, you can insist on using bad coordinates, but that's your own
fault...).

> Have we really all been making this silly mathematical error, and is
> our present understanding of the simplest classical black hole way off
> the mark?

No.

Steve Carlip



And this:



From: Steve Carlip (UC Davis)
Newsgroup: sci.physics.research
Date: 11.04.06, 15:36

Mark Hopkins wrote:

[...]
>> It is trivially true that if one changes coordinates in the standard
>> Schwarzschild solution from r to r-2m, then the horizon is at r=0.

> One can always define the *topology* such that the sphere of symmetry
> at the event horizon is a single point. More generally, a solution only
> defines a spacetime up to homeomorphism. Like it or not, that's a major
> gap in the underlying theory, since there are no principles, in
> general, to determine which topology should apply to a given spacetime:
> the universal covering topology or one of its homeomorphic images.

No, you can't do this in GR -- the point set topology is not uniquely
determined by the metric, but it is also not independent of the metric.

In this case, if you identify the two-sphere at r=2m, t=const. with a
point, the Schwarzschild metric is singular at that point. This means
that the point is not part of the manifold described by the solution of
the field equations, and must be removed. Once the point is removed,
there are standard techniques to analyze the nature of the resulting
boundary (e.g., by treating it as a b-boundary). These show that the
boundary is not a point, and that the geometry can be extended across
the boundary. Do this, and you get the standard Kruskal-Szekeres
solution.

There are certainly situations like the one you describe, in which the
field equations do not tell you whether to use a non-simply connected
manifold or one of its covers. But that's only relevant when the metric
is nonsingular on all of the choices. When the metric is singular, the
theory *does* tell you what to do -- you must remove the points at which
the singularity occurs, and then determine whether you can continue the
solution past the resulting boundary in a nonsingular way.

Steve Carlip


-Richard

publius
2008-Jul-05, 01:10 AM
John Baez, another GR heavyweight familiar to BAUTers had this to say about Mitra's claims in sci.physics.relativity:



From: John Baez
Newsgroups: sci.physics.relativity
Subject: Re: Indian physicist vindicated in black hole controversy
Date: Tue, 17 Aug 2004 18:43:40 +0000 (UTC)

In article *** R. Srinivasan wrote:

>Can you kindly elaborate on the alleged "mistakes" and "blunders" of
>Mitra?

Sure. See below.

>I am interested in this issue for purely logical reasons. In
>particular, is Hawking's latest claim that black holes do not exist in
>the strict sense (which is what Mitra also claimed in his work)
>derived *purely* from the GR postulates or does it involve QM as well?

Hawking's argument involves a combination of GR and QM. Since
there is not yet a full-fledged rigorous theory combining GR and QM,
his argument is necessarily somewhat heuristic. He also hasn't
made the details public yet - he hasn't put a paper on the arXiv.
So, it's premature to try to discuss it in detail.

Mitra's argument involve a combination of GR and mistakes.
GR is a mathematically rigorous theory, so black holes either
exist in this theory or not. Mitra claims they don't; most
people know they do.

>What, if any, are the errors in the earlier (widely accepted) claim
>that the GR postulates imply the existence of black holes in the
>strict sense?

NONE. The errors lie with Mitra, not everyone else in the world.

Here's some old discussion of Mitra's mistakes. I also wrote
my own analysis of his mistakes back when I had to reject some
of his articles on sci.physics.research, but it'd take a bunch
of work to find this now.
...


And then this:



From: John Baez
Newsgroups: sci.physics.relativity
Subject: Re: Indian physicist vindicated in black hole controversy
Date: Thu, 19 Aug 2004 17:54:37 +0000 (UTC)

In article <2ogmqfFait4...@uni-berlin.de>,
LEJ Brouwer <intuitioni...@yahoo.com> wrote:

>"John Baez" <b...@galaxy.ucr.edu> wrote in message
>news:cftjks$2cc$1@glue.ucr.edu...

>Dear John,
>
>It is really quite disappointing to see that the best you can do is to
>regurgitate the same nonsense which Chris Hillman spewed forth at an earlier
>date, and which was also responded to in some detail by Abhas Mitra himself.
>I have attached his response below, which is taken from the earlier
>discussion of this matter on this newsgroup. Given that you have taken the
>time to actually comment on this matter, I hope you will also have the
>dignity to stand by your claims and post a mathematical response.

Dignity, eh? If I had any "dignity" I wouldn't be posting here.

But, it's a lazy summer afternoon, so I guess I'll pass the
time by finding the mistake in this passage by Mitra where
he claims to "prove" that any black hole has mass zero.

The funny part is that he's trying to do this using only
general relativity! Starting from the solution which describes
a black hole of mass m, he attempts by a calculation to show that
m = 0. It's a bit like taking an arbitrary prime number and
proving that it must equal 37.

In an earlier version of his "proof", Mitra's mistake was simple
to spot, since he was using the familiar Schwarzschild coordinates,
and the mistake involved dividing by zero.

Now he has made his argument more complicated by using the less
familiar "LeMaitre coordinates". Luckily, to spot the flaw, all
you need to know is that these are coordinates (r,t) in which someone
freely falling into the black hole stays at constant r as t increases.

(They're vaguely similar to spherical coordinates, and I'm
ignoring the two angular coordinates since they're irrelevant
in what we're doing.)

Okay, here goes:

>For the benefit of the
>serious readers, I give below the essence of my proof:
>
>In Lemaitre coordinates, the radial geodesic (angular part=0), the metric
>of a test particle around a BH is
>
> ds^2 = dt^2 - g_rr dr^2 (1)

I got a bit suspicious right here, since the phrase
"the metric of a test particle" makes no sense. The
metric is something on spacetime, and it applies to
all particles moving in spacetime, so one never speaks
of the metric "of a test particle".

But, it turned out this was only tangential to the main
problem. He's describing the metric for a nonrotating
black hole in LeMaitre coordinates...

>where
>
> g_rr = [(3/2R_g) (r-t)]^{-2/3} (2)

... and I think he's got it right, though I wouldn't vouch for
all the numbers.

>The invariant circumference coordinate R is related to r, t in the following
>way:
>
> R = [(3/2R_g) (r-t)]^{2/3} R_g (3)

I think this so-called "invariant circumference coordinate"
is just the usual radial coordinate R in Schwarzschild coordinates.
R_g is just the number 2M.

>Thus at R=R_g (2M),
>
> [(3/2R_g)(r-t)]^{2/3} = 1 (4)
>
>Using Eq.(4) in Eq.(2), we find that,
>
> g_rr = 1 at R = R_g (5)

All this looks fine - or at least I don't think this is
where the real *problem* lies.

>Using Eq.(5) in Eq.(1), we have
>
> ds^2 = dt^2 - dr^2 at R=R_g (6)

I think this is okay too. At this point, it's best to skip down to
the final "result" and then work backwards....

>Note that while he uses the symbol "r" for circumference coordinate, I am
>using "R" for the same; also while Hillman uses "m" for the gravitational
>mass of the BH, I use "M" for the same.
>
>We would require here a standard result:
>
> dR -(1-2M/R)
> --- = ---------- [E^2 -(1-2M/R)]^{1/2} (7)
> dT E
>
>where E is the conserved energy per unit rest mass of the test particle.
>Since t is the comoving time, we have
>
> dt = (1-2M/R)^{1/2} dT (8)
>
>Now by using the above equations, it can be found that,
>
> (dr/dt)^2 = 1 at R = R_g (9)
>
>Hillman also writes that "it is true that the coordinate slope equals to
>-1 here"; by 'here' he means at R=2M. To verify the correctness of
>Eq.(9), however, it would be better to see the Eq. 3.12.5, pp. 112 of
>Zeldovich and Novikov, Rel. Astrophysics, Vol. 1, Univ of Chicago (1971):
>
> (dr/dt) = +/- (R_g/R)^{1/2} (3.12.5) of ZN
>
>Note that the tau of ZN is our t, r of ZN is our R and vice-versa, and
>recall that we have taken c=G=1.
>
>By putting Eq.(9) in Eq.(6) one can find that INDEED
>
> ds^2 = 0 at R=R_g=2M following the radial geodesic. (10)
>
>If the EH R=R_g were a mere coordinate singularity and actually a regular
>region of spacetime, GTR demands that the geodesic must remain timelike
>there and we should have had ds^2 > 0. Thus Eq.(10) implies that the
>R=2M is NOT a non-singular region of spacetime. [Rather], it corresponds
>to a true physical singularity. But, for a BH, we know that the true
>physical singularity is at R=0. Therefore we can reconcile Eq.(10) with
>this knowledge by recognizing that we must have
>
> R = R_g = 2M = 0 (11)
>
>In other words, the mass of the BH must be
>
> M = 0 (12)

Somehow M = 0 has popped out. It's popped out because in
equation (10) he gets ds^2 = 0 at R = 2M, "following the
radial geodesic". He's not very clear about that means,
but interpreting him generously I'd say he's concluding
the change in proper time vanishes for a test particle
freely falling into a black hole as it crosses the horizon.
This would indeed be a contradition since general relativity
"demands that the geodesic must remain timelike there and
we should have had ds^2 > 0."

So, his mistake may lie in his derivation of ds^2 = 0.
Where does this come from? He says it comes from

ds^2 = dt^2 - dr^2 at R=R_g (6)

and

(dr/dt)^2 = 1 at R = R_g (9)

I've already said I see no flaw in (6) so probably the
flaw is in (9). And indeed, (9) is false for a test
particle freely falling into the black hole: in LeMaitre
coordinates, r is constant for such a particle, so

dr = 0

contradicting (9).

The rest is a mopping-up operation: to see how Mitra
gets ahold of the false equation saying that (dr/dt)^2 = 1.

He gets it by saying "Now by using the above equations,
it can be found that..." where the above equations include
these:

dR -(1-2M/R)
--- = ---------- [E^2 -(1-2M/R)]^{1/2} (7)
dT E


dt = (1-2M/R)^{1/2} dT (8)

But you'll notice he's applying them to the case where R = R_g = 2M.
In this case they say:

dR/dT = 0

dt = 0

So, he's dividing by zero if he wants to use these to compute
dr/dt!

I still don't see how he's trying to get (dr/dt)^2 = 1, since
he doesn't exhibit his reasoning - he just says "it can be found".

But, I see that it's false, and I see that he's dividing by zero
in his steps towards this.

So much for his "proof".

In a way, it's just a more complicated version of his argument that got
rejected on sci.physics.research. When push comes to shove, Mitra divides
by zero.


When push comes to shove, Mitra divides by zero, sayeth Baez. :)


-Richard

publius
2008-Jul-05, 01:38 AM
And finally, about the MECO/ECO proponent claim that somehow radiation pressure can halt the collapse (or whatever it is supposed to be). There exists a exact solution of the EFE known as the Vaidya Null dust, which involves the gravitational collapse of a ball of incoherent radiation (null dust).

So right there that has radiation of itself collapsing to a singularity under its own gravity.

All of this puts Mitra and Co's on shaky ground indeed. I wasn't aware of the Vaidya null dust solution until recently.

-Richard

William
2008-Jul-05, 02:49 AM
In reply to Publius,


In reply to Publius' general comments: "I was vaguely familiar with the MECO/ECO idea which I thought was "black holes can't really form in nature", due to something about radiation pressure of gravitationally bound radiation. That is, the thing would not collapse to a singularity in its own proper time."

"However, I recently learned that the MECO/ECO proponents are basing all this on some pretty dubious, fairly nonsensical notions."

My General:
Another way to look at the problem is to start at 1000 ft. Why do we believe the hairless black hole hypothesis/mechanism, with an event horizon that encloses a singularity is any better than the competing MECO hypothesis? I have heard because the hairless black hole hypothesis is discussed in text books, the MECO is not. I have heard based on the number of authors that are promoting theory. Are there any other clues to select one hypothesis over the other, besides the number of authors who are promoting the new hypothesis and whether the hypothesis is included in a text book? Logically everyone will not at first support a new hypothesis. That is not likely. Each field and problem has it own peculiar issues at a human level. (Humans are not robots.)

There are papers that have been published in scientific journals that promote the MECO hypothesis. The first paper was published in 1999. (Looks to be around thirty published papers on the subject.) The authors of the papers are all mainstream scientists working at universities or in the case of Mitra a prestigious theoretical group. The authors in question have presented their hypothesis, the supporting data, and logic at conferences. No other scientists have been able to refute the MECO hypothesis in a published paper. I would suggest that those facts should elevate the probability that the MECO hypothesis is a mainstream hypothesis that could possibly be a contender.

My objective is to move the MECO hypothesis from against mainstream to mainstream. I would also like to understand the observations and issues better. A question might be: Is the fact that there are published papers by a group of reputable scientists sufficient for the MECO hypothesis to be mainstream? Might be, but I support some process that helps us understand the science better.

Observational Facts & Issues to Explain
There is direct observational evidence which indicates that quasars/AGN have massive magnetic fields in their core region. There are observations where the existence of a very strong magnetic field at the core of quasars and AGN, would explain what is being observed. There are ultra fast jets of matter being injected from quasars and AGN. There is no mechanism to generate the magnetic field with a hairless black hole. As Mitra notes above, other astrophysical objects (a neutron star for example) which can generate their own magnetic field, can create jets. Mitra is inferring that if a massive compact object could generate a massive magnetic field, the massive magnetic field could create the jets.

There is observational evidence of a quasar where the core accretion disk area was been swept clean. Detailed analysis of that quasar and other quasars shows there is a massive magnetic field in the quasar/AGN core region.

A hairless black hole cannot generate a massive magnetic field. For the hairless BH hypothesis, the accretion disk must generate the massive magnetic field.

There are other authors noting that the accretion disk cannot produce the observed AGN/quasar magnetic field. The MECO authors quoted papers by other authors which support that assertion.


http://www.google.com/search?q=Black...e7&rlz=1I7GWYE

The following is an excerpt from a lecture on accretion disk generated magnetic fields. As others have noted there is no physical mechanism for the accretion disk to generate the massive magnetic field that is required to explain the AGN jets.


“And then the theorist raises his magic…. I mean magnetic wand… and viola, there are jets” - Shri Kulkarni

Lots of Mechanisms proposed, but most boil down to a reference to the still unsolved mechanism behind the jet mechanism for Active Galactic Nuclei (Generally the Blandford-Znajek Mechanism).

We are extrapolating from a non-working model – dangerous at best.


In reply to Publius' technical comments (1)

They actually argue that the Schwarzschild vacuum itself is flawed, by some argument that the "horizon is really a point, not a spherical surface", and is a true, essential singularity, and not a coordinate one and somehow that implies the total mass M must be 0. They go on to state that nothing could actually fall into a *pre-existing* Schwarzschild black hole in its own proper time.


Mitra’s paper states that a massive collapsing object will generate heat as it converts its self gravitational energy to particle motion. The heat/particle motion will stop the collapse of the body. After the collapse what will be left is a body that is very, very hot and that has a highly redshifted surface and that has a very strong magnetic field.

The body is not in equilibrium at this point. The body will continue to radiate and will asymptotically reach zero mass after a very long period of time. The massive object will not be massive when it was finished collapsing because it will have radiated all of its energy away.


In reply to Publius' technical comments (2):
The latter argument is based on an erroneous claim that the world lines of infalling test particles would become null (light-like) at the horizon. Their argument against the Oppenheimer "cold dust collapse" is also based on the claim that world lines of the collapsing dust particles would become null.


The massive collapsing body will continue to collapse and to radiate and will asymptotically reach zero mass after a very long period of time. The massive object will not be massive when it was finished collapsing because it will have radiated all of its energy away.

Note Mitra's hypothesis is that the MECO is an eternally collapsing object, it is not really eternally collapsing, but the word 'eternal' is used to emphasis that the collapse is a very long process. The massive collapsing object cannot as the hairless black hole solution hypothesized jump to a singularity surrounded by an event horizon.

There is no reason to discuss an event horizon, because Mitra provides logic to show the collapse of the massive object is stopped. Mitra is both a GR expert and a physicist. As he states in his paper, even if the conversion of self gravity energy did not stop the object from collapsing there are theoretical and physical issues with what is described in the hairless solution as a "event horizon" and what it encloses, the BH singularity.

Perhaps Mitra should not have added those arguments as that discussion which is completely theoretical (if the MECO hypothesis is correct) appears to be a distraction from the science and theoretical issues related to the physical problem, as opposed to a toy problem.

William
2008-Jul-05, 04:17 AM
Hi Publius,

The following is an excerpt from Mitra’s paper that supports what I said. Carlip’s comments concerning Hilbert’s work are therefore not relevant to this discussion. (i.e. Mitra’s hypothesis is radiation energy stops the collapse of the massive object so the discussion of the event horizon is purely theoretical, if Mitra’s hypothesis is correct.)

John Baez’s comments are made with the assumption that Mitra’s hypothesis is a simple mathematical manipulation that changes the mathematical result of the collapse of the massive object. Baez does not reference a Mitra paper, so I am not sure why he made those comments. As shown in the next quote from Mitra’s paper, M=0 is that is the asymptotic final state of the collapsing massive object. (i.e. Object is eternally collapsing and asymptotically by radiating reaches M=0. See below for details.)

It should also be noted that there is significant observational data to support the MECO hypothesis. From a practical standpoint (to solve the problem) it is awkward that the GR specialists are not interested in the quasar and AGN observations. The other MECO supporters appear to be quasar experts and knowledgeable astrophysicists. Logically if the massive object has an intrinsic magnetic field it is a MECO rather than a hairless black hole. Observations in most cases can be used to prove or disprove theory. I would assume Baez is not an astrophysicist based on his strident belief that the hairless black hole solution could not possibly be incorrect and his indifference to physics/observations of the objects in question.

“Sources of Stellar Energy, Einstein- Eddington Timescale of Gravitational Contraction and Eternally Collapsing Objects” by Abhas Mitra

http://arxiv.org/abs/astro-ph/0608178


Since uEE refers to a depletion of mass energy, one expects M = 0 for the end product. Thus the BH formed asymptotically should have a unique mass M = 0. And it has indeed been shown that the integration constant which appeared in the so-called vacuum Schwarzschild solution has the unique value of zero: α0 = 2M = 0 (Mitra 2005, 2006b,c,d,e). Physically, as the continued collapse process becomes eternal, all available mass energy is radiated away. However, a BH with M = 0 does not necessarily mean absence of matter or violation of any baryon/lepton number. All it means is that total positive mass energy associated with baryons, leptons and radiation gets exactly offset by negative self-gravitational energy. We may see now that this profound conclusion is indeed consistent with the phenomenon of GR collapse.


A vacuum Schwarzschild solution, actually Hilbert solution (Mitra 2006f), with a supposed M > 0 yields the traditional BH paradigm. On the other hand, a solution with supposed M < 0 is equally valid from pure mathematical perspective and would yield a “Naked Singularity” (NS) without an Event Horizon (EH). Thus, a M = 0 BH is a borderline case between the two and it is no spacetime singularity at all because it requires infinite comoving proper time to form : τ = ∞.


By thermodynamics, the equation of state (EOS) of the fluid under consideration may be represented as p ∝ ρ^Tau and conversely ρ ∝ p1/tau. Then clearly a p → 0 situation implies ρ → 0. And if ρ = 0, we would have M = 0 and so would be the self-gravity; = 0. Thus from physics point of view, if the only exact solution of collapse of a uniform dust is really to be considered as a mathematical physics problem, the mass of the BH formed therein is M = 0. Since the proper comoving proper time of its formation is τ ∝ M^−1/2, clearly, the actual value of τEH = τsingularity → ∞ in this problem. This understanding has several ramifications. When one erroneously assumes M > 0 for this idealized collapse, one obtains the traditional BH paradigm where the finite mass BH is formed in prompt free fall time scale while the time scale of its formation as recorded by an astronomer is infinite (tEH = ∞). In other words although an astronomer would never see a BH, it is supposed to be formed only w.r.t. a local observer outside the realm of observed physical universe. This is at variance with the principles of all theories of relativity, Galilean, Special or General. The spirit of relativity is that “rulers” and “clocks” could indeed be different for different observers and so could be the measured numerical values of relevant physical quantities. However, if the physical phenomenon is observable to one observer, it must be observable to all, if it is not observable to a given observer, it must not be observable to any other observer either.




In GR collapse equations, physics appears when one considers (i) an EOS of the collapsing fluid, (ii) the evolution of the EOS at arbitrary high pressure, temperature or other relevant parameters, (iii) generation of heat/radiation within the body due to dissipation and (iv) propagation of the outward radiation and its effect on the collapsing fluid in a self-consistent manner. Without such physical aspects, the GR collapse problem becomes a mere exercise in applied/numerical mathematics something like the dissection of a corpse without any flow in the veins and a throbbing heart. Yet starting from OS, even now, many authors avoid all such intractable physical aspects by setting p ≡ U ≡ 0 in the problem. Technically, this is known as “dust approximation”. Formally, one can also assume the “dust” to be inhomogeneous instead of the homogeneous case considered by OS . But once one assumes inhomogeneity, infinite forms of inhomogeneity (even though density would be assumed to decrease with R) can be assumed. Then complexity of the GR collapse equations offer infinite scope for various additional applied mathematics exercises. In particular, in some cases, it is claimed that, instead of a BH with an EH, there may be “Naked Singularity” where the central singularity forms before the central region gets trapped and hence, the central singularity may be visible either momentarily or permanently (Joshi 2004).

loglo
2008-Jul-05, 06:42 AM
William,
Is there more than one observation of a quasar that support the MECO hypothesis? Do any of the other observations "rule out" a MECO type object?

William
2008-Jul-05, 01:55 PM
Hi Publius,

(P.S. Thank you your comments and the comments of others. I am going to be out of town next week, Sunday to Sunday, and must get ready for the trip today. I will be able to respond to your or others comments, as soon as I get back. The following is just issued to clarify and to note I will be delayed in a response.)

From a physically standpoint, the key issue is there sufficient internal energy to stop the collapse of the massive object. Mitra’s notes that past simulations were physically not reasonable as they assumed q=0. He references below other authors who have run simulations that show the massive object becomes an eternally collapsing object, rather than the abrupt collapse to form a hairless black hole, with an event horizon and singularity.

As Mitra notes the internal energy of the massive object theoretically can be redistributed, to stop the collapse. Is that a reasonable physical assumption? Why would we assume that massive objects do not redistribute their internal energy to stop the collapse?

The following is another excerpt from Mitra’s paper.

http://arxiv.org/abs/astro-ph/0608178

8.4 Physical Gravitational Collapse
Gravitational collapse must be accompanied by emission of radiation/heat flow from the collapsing fluid. The density of radiation within the fluid gets enhanced by (a) matter-radiation interaction (diffusion) by which ρr increases from the value on would obtain using free streaming assumption (Mitra 2006a). And in the z≫1 regime ρr also increases (b) due to trapping of the radiation by self-gravitation of the fluid (Mitra & Glendenning 2006). The process (a) has recently been specifically considered. In a very important paper Herrera & Santos (2004) have shown that the effect of outward flow of heat can stall the GR continued collapse. This pioneering suggestion has been confirmed by Herrera, Di Prisco and Barreto (2006) by means of a specific numerical modeling. In another related work, Cuesta, Salim and Santos (2005) have found that Newtonian supermassive stars undergo collapse to form a hot quasistatic eternally collapsing object (ECO) rather than a static cold BH. Such works however have not considered the generic mechanism (b) of self-gravitational trapping of radiation/heat. On the other hand if this mechanism would indeed be implemented in an appropriate numerical scheme, it would be found that ECOs rather than BHs are formed for arbitrary initial mass of the fluid provided it is dense enough to undergo continued collapse to z → ∞.

The second issue is more a GR discussion, but I find it interesting. It should be noted, however, if the massive object can by redistributing its internal energy stop the collapse, we are discussing a non-physical toy model. I believe Mitra’s point is that there are fundamental problems with the event horizon and singularity solution anyway. The danger with that approach is it can and seems to have become a distraction.

If however it can be shown that the event horizon surrounding a singularity is physically and mathematically not reasonable for the toy model case, it starts the question of why did that solution get accepted? Also because Mitra’s looking at the toy model from a critical standpoint, it helps to understand the GR and how to approach problems in general.

The following is an excerpt from Mitra’s paper that discusses the event horizon and its properties.


9.3 Non occurrence of Trapped Surfaces
The singularity theorems buttressing the BH and Naked Singularity paradigms are based on the assumption that trapped surfaces are formed in continued spherical GR collapse. But it was shown very transparently that trapped surfaces do not form in GR collapse (Mitra 2004a, 2006f):

(2GM(r)/R) ≤ 1 (58)

where r is the comoving radial coordinate. In contrast, formation of trapped surfaces demand 2GM(r)/R > 1 and the equality sign denotes formation of an “apparent horizon”. Eq.(58) shows that under the condition of positivity of mass, one must have M → 0 as the singularity would be approached R → 0. If one would have 2GM/R < 1 at the singular state, there would be no horizon, and M should wander towards the negative branch. Thus one must approach the equality limit of a zero mass BH : 2GM/R → 1 as R → 0. However since the worldlines of the fluid must always be timelike, this limit which corresponds to a null condition must not ever be attained. In other words, one must have τ → ∞ as R → 0. We saw this categorically for the dust collapse.

The physical reason for non-occurrence of trapped surfaces is again “nothing can move faster than light” because it was shown that occurrence of a trapped surface would mean the local 3-speed of the collapsing fluid would exceed the speed of light v > c (Mitra 2004a, 20056e). In fact, at the “apparent horizon”, one should find the acceleration of the fluid to blow up. Therefore, an apparent horizon cum EH may only asymptotically form as R → 0 and M → 0. Unfortunately the BH and singularity “experts”, having already made too much commitment and investment in the BH/singularity paradigm, found both the exact derivation of the theorem of non-occurrence of trapped surfaces and its physical interpretation to be most inconvenient and chose to quietly ignore them. Since an EH is never formed, there is no trapping of any quantum information within any EH. Thus actually, there was never any Hawking radiation or Quantum Information paradox. And obviously there need not be any resolution of this paradox either because, in reality, it was never there because BH mass M ≡ 0 (Mitra 2006f). ...


9.2 Acceleration at the Event Horizon
It is also known for long that radial component of the 3-acceleration aR of the test particle blows up at the EH. This profound physical result, inconvenient for the BH paradigm, has traditionally been brushed aside by mentioning that suitable coordinate transformations may remove this singular acceleration by ignoring the simple STR result that if acceleration is infinite in one frame, it is so in any other frame. Later it was pointed out that one can construct an acceleration scalar which too behaves in exactly the same singular way. This unequivocally showed the physically singular nature of the EH, which implies that the EH itself is the central singularity (i.e., M = 0) (Mitra 2002a,b). However “BH experts” found such conclusions inconvenient and pretended to be unaware of it. Recently MacCallum (2006) has admitted that the acceleration scalar indeed blows up not only at the horizon of only Schwarzschild BH but for all BHs, for instance, spinning Kerr BH. However, in order to still uphold the BH paradigm, he has suggested new mathematical criterion for the definition of spacetime singularities completely ignoring that any such new rule would not change the basic fact that the physically measurable acceleration would blow up at the horizon in a coordinate independent manner. Recall, the original claim for supposed spacetime regularity at the EH was that “no singular unusual physics happens there”. Thus clearly this attempt by MacCallum to uphold the BH paradigm is unjustified and inconsistent from the point of view of the accepted notion about a “regular event horizon”. At this rate, one can claim that attainment of speed of light by a material particle is no violation of GR. In reality, at least for a material test particle attainment of infinite (scalar) acceleration and infinite Lorentz factor (v = c, γ = ∞) are closely related phenomenon.

antoniseb
2008-Jul-05, 08:27 PM
My objective is to move the MECO hypothesis from against mainstream to mainstream. I would also like to understand the observations and issues better.

Hi William,

for the time being, we will be keeping MECO and tangential ideas in ATM. I personally am not well versed in the many solutions to GR as pertain to very massive/dense objects, and so I won't be making many claims in this topic.

The dilemma I have is that I believe that GR has been tested in many physical observations, and come up looking good, but the behavior of matter and energy in close proximity to what would be an event horizon is an extrapolation. My point being that I generally trust the mainstream GR people who claim Mitra is wrong, I believe that it is worth finding additional observations that might distinguish between the models, or potentially find data showing both are wrong.

It seems like there should be a few observable differences in:
- stellar-mass black-hole candidates in tight orbits with other stars
- the magnetic influences of Sgr A* (which has no appreciable accretion disk)
- maybe in the solo bhc observed by [OGLE or SuperMACHO] a few years ago.

I'd be interested in seeing something identifying observability limits on the differences in these systems.

William
2008-Jul-14, 11:45 PM
Hi Antoniseb,
The following is in reply to your comment:


Antoniseb said: The dilemma I have is that I believe that GR has been tested in many physical observations, and come up looking good, but the behavior of matter and energy in close proximity to what would be an event horizon is an extrapolation. My point being that I generally trust the mainstream GR people who claim Mitra is wrong, I believe that it is worth finding additional observations that might distinguish between the models, or potentially find data

As outlined in this paper by Leiter and Robertson there is a simple and strong theoretical argument, that uses GR to support the assertion that hairless black holes cannot physically exist. The hairless black hole solution is not a viable solution to what happens when a massive physical object collapses.

I would suggest that the MECO hypothesis is mainstream. The hairless black hole solution, is ATM. There are no mainstream GR people that are defending the hairless black hole solution. There are roughly 30 published papers that show that the hairless black hole solution is not correct. There is published observational evidence to support the MECO solution to what happens when a massive black hole collapses.

The MECO solution is consistent with GR. The first paper concerning this subject was published in 1999. There has been sufficient time for any GR specialists to defend the hairless black hole solution. They have not. As noted Steven Hawkins has stated publicly (obliquely) that hairless black holes do not exist.

There are as of yet no tangential theories related to MECOs. If there were perhaps they could be moved to ATM.

Comments:
1) I have taken a couple of excerpts from the pre-print paper by Leiter and Robertson. The actual paper has been published by Springer in their book “Foundations of Physics Letters”.

2) The theoretical argument that hairless black holes cannot form is buttressed by AGN observational evidence which supports the assertion that the massive black hole candidate at the core of the AGN, have an intrinsic massive magnetic field which is physically not possible for a hairless black hole.


“Does the Principle of Equivalence Prohibit Trapped Surfaces from Forming in the General Relativistic Collapse Process?” by Darryl Leiter and Stanley Robertson

http://arxiv.org/abs/astro-ph/0111421


In General Relativity, the Strong Principle of Equivalence requires that Special Relativity must hold locally for freely falling time-like observers in all of spacetime. Since this requirement is a tensor relationship it implies that the proper time along the time-like spacetime world lines of physical matter with non-zero rest mass must always be positive definite dτ>0. In order to satisfy this Principle of Equivalence requirement, the time-like world lines of physical matter under the influence of both gravitational and non-gravitational forces must not become null in any regular region of space time. Spacetime manifolds which have this property are called “bundle complete” ( see pages 69-71 in Wheeler, A., Ciufolini, I., “Gravitation and Inertia”, (1995), Princeton University Press Princeton, New Jersey). …


We then argued that Principle of Equivalence enforces this ”no trapped surface condition” by constraining the physics of the general relativistic radiation transfer process in a manner which requires it to establish and maintain an Eddington limited secular equilibrium on the dynamics of the collapsing radiating surface so as to keep it outside of its Schwarzschild radius during the collapse process and thus prevent the physical surface of the collapsing object from ever forming a trapped surface. We found that the dynamic radiation transfer condition required for the existence of the high redshift Eddington limited stationary equilibrium, associated with the gravitational collapse of a compact object made up of a radiating plasma satisfying the Principle of Equivalence, is that it must contain an intrinsic equipartition magnetic field energy density which is less than or equal to its gravitational field energy density.


…In order for the Principle of Equivalence requirement (7) to be satisfied by a collapsing redshifted spherical surface of radius RS >RSchw containing plasma with gravitational mass MS , the physics associated with the radiation transfer within the collapsing plasma must eventually allow it to start emitting photons at the local Eddington limit LEdd . This is because under these conditions the local radial proper time rate of change of the radius of the surface (US / c) can be vanishingly small and the Principle of Equivalence “no trapped surface condition” requirement RS >RSchw for the collapse can be dynamically satisfied by the equations of motion of the matter. …

Hence the Principle of Equivalence requires that the physical dynamics associated with the general relativistic radiation transfer process must establish an Eddington limited secular equilibrium on the collapsing surface (2) (3) before it has a chance to pass thru the Schwarzschild radius of the collapsing object. In Appendix A we show in detail that when the Eddington limit is established at red shift (1+z) = (1+ zEdd) , the Principle of Equivalence applied to the Einstein Equation implies that the time like collapsing radiating surface of the MECO lies outside of the Schwarzschild radius of the collapsing object and remains that way for the duration of the Eddington limited collapse process. In Appendix B we show that if LEdd(escape) S is the luminosity generated by the interior physics of the which escapes through the collapsing MECO surface, the red shift at which an Eddington balance …


…In previous work [2] on galactic black hole candidates (GBHC) containing MECO with M* = 10, the distantly observed magnetic fields were ~10^10 gauss which implied that (1 + zS) ~ 10^8. This value of (1 + zS) ~10^8 is also consistent with the case of AGN with M* = 10^8 since then the distantly observed magnetic fields would be ~ 10^4 gauss consistent with what is expected in the AGN accretion disk environment.

William
2008-Jul-15, 02:23 AM
In reply to Publius,

Publius said:
At any rate, Steve Carlip, an expert in GR, who should be familiar to many BAUTers (I've used one of his papers as the reference for the many "speed of gravity" questions that pop up here), had this to say in a post to sci.physics.research about these papers:

Two of these "Schwarzschild is wrong" papers, on which Mitra and others base their notions are these:

by Abrams and Antonci respectively.

http://arxiv.org/abs/gr-qc/0102055

http://arxiv.org/abs/physics/0310104


Hi Publius,

This paper by Leiter and Robertson does not reference Anotonci’s paper. Leiter and Roberstson's paper is not based on Anotonci’s paper. Anotonci’s paper could very well be incorrect. Leiter and Robertson’s paper is not. You have copied correspondence by Carlip and Baez that discusses Antonci’s paper which is not relevant to this discussion.

There is not a transformation of coordinates in Leiter and Robertson’s paper. Leiter and Robertson use the Strong Principle of Equivalence which is a pillar of GR to show that a hairless black hole cannot form.

Leiter and Robertson show that a massive object takes a very, very long time period to collapse and hence a hairless black hole does not exist as it could not possibly have had time to form.

Previous solutions to the massive collapsing object problem did not consider the problem as a real physical problem. There is a point in time before the black hole can form. There is a transition as the massive object changes to ???. What is the time period required to go from massive object to ???. In falling matter generates heat and a magnetic field which stops the collapse of the massive compact object.

??? is not a hairless black hole. The MECO solution is consistent with GR.

Comment:
I have taken a couple of excerpts from the pre-print of Leiter and Robertson's paper. The actual paper has been published by Springer in their book “Foundations of Physics Letters”.

“Does the Principle of Equivalence Prohibit Trapped Surfaces from Forming in the General Relativistic Collapse Process?” by Darryl Leiter and Stanley Robertson

http://arxiv.org/abs/astro-ph/0111421


Recent observations of the quiescent luminosities of Neutron Stars (NS) and Galactic Black Hole candidates (GBHC) have suggested that both NS and GBHC possess intrinsic magnetic moments [2]. Accommodating intrinsic magnetic moments in such objects will clearly require revisions in the current theoretical description of these compact objects in the context of General Relativity because if GBHC are Black Holes with Event Horizons they could not exhibit the effects of any internal magnetic field.

Albert Einstein attempted to show that Black Holes with Event Horizons were not allowed by the General Theory of Relativity [3] , however his argument lacked the complete theoretical formalism associated with the concept of black holes and gravitational collapse. Using the currently known general formalism for spherical collapse in the context of an interior co-moving observer, and noting that the Principle of Equivalence requires that the worldline of timelike matter trajectories must remain time-like in all regions of space time [4], it has been recently shown [1] that no trapped surfaces can be formed in spherical gravitational collapse. While the above result was obtained by treating the problem from the viewpoint of an internal co-moving observer at radius r, the boundary of the fluid at rs = Rs(rs , t) must also behave in a similar manner, and an external stationary observer should also observe the same no trapped surface relationship.

Since the Principle of Equivalence does not allow the time-like world line of physical matter, being acted on by both gravitational and non-gravitational forces, to become null in any regular region of space time, we show in section II that this requires that the condition 1 / (1+z) > 0 must hold, where z is the red shift of the physical matter moving along its world line as seen by a distant observer. In section III adopt the viewpoint of a stationary observer in the exterior metric of a time-like collapsing plasma which is radiating photons while obeying the Principle of Equivalence requirement that 1 / (1+zs) > 0 must always hold. Then the Einstein equation can be solved with an appropriate energy momentum tensor and boundary conditions for the metric.

When the Principle of Equivalence requirement that 1 / (1+zs) > 0 is applied to the first integral of the mixed time-time component of the Einstein equation, with appropriate boundary conditions on the time-like surface surrounding the collapsing radiating plasma, we find that it requires that the “no trapped surface condition” 2GMS / RS c2 < 1 must hold on the physical boundary of the collapsing radiating plasma , consistent with earlier work done for so-called Eternally Collapsing Objects (ECO) in the context of a co-moving observer in an interior metric[1].


In Appendix A we discuss this point in more detail and show that in the context of the Einstein equations for a collapsing, radiating plasma, the Principle of Equivalence (POE) requires that the physics associated with the general relativistic radiation transfer process in the MECO must dynamically establish an Eddington limited secular equilibrium condition on the collapsing surface of the MECO before the collapsing surface has a chance to pass thru the Schwarzschild radius of the collapsing object. Finally we consider the observational implications of this result for intrinsic magnetic moments for GBHC [2] and argue that the non-existence of trapped surfaces becomes manifest observationally in the fact that the spectral properties of the radiation emitted by GBHC can be consistently understood in terms of a unified model of Magnetospheric Eternally Collapsing Objects (MECO) within the framework of General

Disinfo Agent
2008-Jul-15, 11:51 AM
The hairless black hole solution is not a viable solution to what happens when a massive physical object collapses.

[...] There are no mainstream GR people that are defending the hairless black hole solution.Whatever happened to the No Hair theorem (http://www.answers.com/topic/no-hair-theorem?cat=technology)?

thomheg
2008-Jul-15, 01:54 PM
Whatever happened to the No Hair theorem (http://www.answers.com/topic/no-hair-theorem?cat=technology)?
It says, that all other properties of the objects falling in except mass, charge and angular momentum are inaccessible. Imagine a light cone from an object falling into a BH. Than this feature would fit to a timelike hypersheet of that objects spacetime, that is bending away from us. Causality would prevent that object to be seen by us. But it is still there, in it's own frame of reference. All other features of a BH -btw- would also fit into such a picture of curved spacetime and the BH would vanish, if seen from there.

William
2008-Jul-15, 02:37 PM
In reply to Disinfo Agent's comment:



Quote:
Originally Posted by William View Post
The hairless black hole solution is not a viable solution to what happens when a massive physical object collapses.

[...] There are no mainstream GR people that are defending the hairless black hole solution.

Disinfo Agent said:
Whatever happened to the No Hair theorem?

The "hairless black hole" solution to what happens when a massive object collapses ignores the transitional phase when a massive object collapses to form ???. The hairless black solution is physically not possible. The no hair solution is a solution to a toy model assumption. i.e. Ignoring the physics of the massive object transitional phase, let's postulate a mathematical answer to a toy model assumption. An event horizon is a toy model structure. In reality the massive object gets hotter as it collapses and it generates a massive magnetic field. The massive magnetic field creates electron/positron pairs in the collapsing object which stops the collapse.

The massive magnetic field which is intrinsic to black hole candidates, is required to explain AGN observations such as jets. Matter is accelerated at the poles of AGN to a speed of up to around 0.9 C.

There is observational evidence of the massive magnetic field in the core of AGN. For example:

Black Hole or MECO? Decided by a Thin Luminous Ring Structure Deep within Quasar Q0957+561 By Rudolph Schild and Darryl Leiter

http://arxiv.org/abs/0806.1748v1


Optical, Infrared, X-ray, and radio wavelength studies of quasars are beginning to define the luminous quasar structure from techniques of reverberation and microlensing. An important result is that the inner quasar structure of the first identified gravitational lens, Q0957+561 A,B seems not to show the kind of structure expected for a supermassive black hole, but instead show a clean-swept interior region as due to the action of a magnetic propeller, just as expected for a MECO (Magnetic Eternally Collapsing Object) structure. Given the present state of the observations, the strongest model discriminant seems to be the existence of a thin luminous band around the inner edge of the accretion disc, at a distant radius ~ 70RG from the ~ 4×10^9M⊙ central object. Since the existence of a clean magnetic propeller swept inner region ~70 RG surrounded by a sharp ~ 1 RG disc edge are the low-hard state spectral properties associated with a highly redshifted central MECO object, we are led to the conclusion that these observations imply that the Q0957 quasar contains a central supermassive MECO instead of a black hole. In this report we review the details of the observations which have compelled us to reach this conclusion.

William
2008-Jul-15, 03:08 PM
In reply to loglo's comment:
Is there more than one observation of a quasar that support the MECO hypothesis?

Yes. (Q2237 in addition to Q0957, as noted in below when Large Scale Synoptic Telescope is place in service The MECO's magnetic field can explain the switching on and off of the AGN radio lobes. The following is a paper that compares the radio quiet Q2237 to the radio loud Q0957.

Direct Microlensing-Reverberation Observations of the Intrinsic Magnetic Structure of AGN in different Spectral States a Tale of two Quasars by Rudolph Schild, Darryl Leiter, and Stanley Robertson

http://arxiv.org/abs/0708.2422v1


We show how direct microlensing-reverberation analysis performed on two well-known Quasars (Q2237 - The Einstein Cross and Q0957 - The Twin) can be used to observe the inner structure of two quasars which are in significantly different spectral states. These observations allow us to measure the detailed internal structure of quasar Q2237 in a radio quiet high-soft state, and compare it to quasar Q0957 in a radio loud low-hard state. We find that the observed differences in the spectral states of these two quasars can be understood as being due to the location of the inner radii of their accretion disks relative to the corotation radii of rotating intrinsically magnetic supermassive compact objects in the centers of these quasars.


In summary we have demonstrated how direct microlensing-reverberation analysis of two Quasars (Q2237 - The Einstein Cross and Q0957 - The Twin) have allowed us to observe inner structure of two quasars which are in significantly different spectral states. Standard black hole accretion disk models were found to be unable to offer a unified dynamical explanation of the observed internal structure of both of these two quasars in different spectral states. Instead we found that a unified explanation could be obtained within the framework of a MECO model. This was done by describing the spectral states of the two quasars in terms of the location of the magnetospheric radii of their accretion disks with respect to the co-rotation radii, inside of the light cylinder surrounding highly red shifted, rotating M ~10^9M⊙ MECO in the centers of these quasars.


Because of the apparent ease with which the size of the Elvis structure and the quasar orientation with respect to the plane of the sky can be inferred, following the method of S05, future photometric observations with the planned Large Scale Synoptic Telescope (LSST) will allow an important MECO parameter to be easily obtained for any of the thousands of quasars to be monitored. Since the radius of the MECO outer light cylinder depends only on the distantly observed MECO period of rotation, the connection between the MECO outer light cylinder and the location of the Elvis outflow structures observationally determines the distantly observed MECO spin parameter. Hence, in addition to the MECO mass and intrinsic magnetic moment, simple recognition of patterns of reverberations and their timing allows distantly observed MECO spin parameters to be obtained.


Large Synoptic Survey Telescope (LSST) Receives $14.2 million National Science Foundation Design and Development Award
September 2, 2005

TUCSON, Arizona - The Large Synoptic Survey Telescope (LSST) has received the first year of a four-year, $14.2 million award from the National Science Foundation to design and develop a world-class, 8.4-meter telescope scheduled for completion in 2012


http://www.bnl.gov/bnlweb/pubaf/pr/PR_display.asp?prID=05-X16

William
2008-Jul-22, 03:10 AM
As this paper, notes contrary to what some papers have claimed, the SGR A* observations have not proved that SGR A* has an event horizon. The observed near infrared radiation (NIR) is consistent with the MECO predicted luminosity. The MECO is hypothesized to have a highly redshifted surface.

In addition, as the authors of this paper note, there are polarization observations of SGR A* that show SGR A* has an intrinsic magnetic field that is consistent with the MECO hypothesis.

Comment:
The Milky Way Galaxy’s black hole candidate is located in the constellation (Sagittarius A) and is therefore called SGR A*.

http://arxiv.org/PS_cache/astro-ph/pdf/0505/0505518.pdf

Does SGR A* Have an Intrinsic Magnetic Moment Instead of an Event Horizon? Stanley L. Robertson and Darryl Leiter


We have previously developed a general relativistic model of a gravitationally compact, intrinsically magnetic, eternally collapsing object (MECO). It has been shown to account for the low quiescent x-ray luminosities and spectral state switches in galactic black hole candidates (GBHC) while correctly predicting the radio/x-ray luminosity correlations of both GBHC and active galactic nuclei. We show here that a MECO model for Sgr A* is consistent with its observed low NIR luminosity levels. It has the unique property of providing an explanation for observed polarizations in the context of an inverted polar jet flow while reconciling the low luminosity of Sgr A* with a standard Bondi accretion low. Thus the conclusion that Sgr A* contains a black hole with an event horizon is still unsubstantiated.

This paper also includes a succinct summary of the MECO physics. The key theoretical point of the MECO hypothesis, is that a collapsing massive object "must necessarily pass through high redshift states that are strongly dominated by radiation pressure." As noted above the MECO hypothesis is consistent with GR.

There are no comments presented above by Carlip or Baez that even attempt to address the MECO theoretical argument that a massive collapsing object 'must necessarily pass through high redshift states that are strongly dominated by radiation pressure" or the observations presented above that support the MECO hypothesis.

There appears to have been no public formal attempt to defend the hairless black hole hypothesis. I believe the theoretical issues are reasonably straightforward MECO vs Hairless BH. I will do some work to clarify the two different positions and then will see if I can generate a discussion by the GR experts. I would like to see a proper summary of the science and scientific differences developed that can be presented to knowledgeable, non GR specialists.


The collapse rate of a MECO is stabilized, at extremely high values of the surface red shift, by Eddington limited radiation pressure generated from internal equipartition magnetic fields contained within its surface. Due to the fluid interior of the MECO, its magnetic moment aligns with its rotation axis. As described in RL05, the interior magnetic field in a stellar mass MECO-GBHC is about what would be expected from flux compression during stellar collapse, but the external field is primarily produced by General Relativistically created electronpositron drift currents on the MECO surface that drive the external surface field to the threshold of quantum electrodynamic production of bound pairs in the MECO surface.


The ratio of tangential field on the exterior surface to the tangential field just under the MECO surface allows a determination of the surface redshift (RL05) as given by Eq.1, Table 1. In this regard, it has been shown (Abramowicz, Kluzniak & Lasota 2002) that it will be extremely difficult to provide convincing arguments for event horizons if objects with suitably high redshift exist. Mitra (2006a,b) has shown that before collapsing objects can become black holes, they must necessarily pass through high redshift states that are strongly dominated by radiation pressure.


Radiation escapes from the MECO surface at the local Eddington limit, which is larger than the conventional Newtonian Eddington limit by a factor of 1 + zs. Distantly observed luminosity is reduced below that escaping the surface by a factor of (1+zs)^2. The MECO radiative decay lifetime is extended by the factor 1 + zs and greatly exceeds a Hubble time. The quiescent MECO luminosity observed distantly is reduced by the same factor, Eq. 2, Table 1. The distantly observed quiescent surface temperature is that of the photosphere of a radiation dominated electron-positron pair atmosphere and is given by Eq. 3, Table 1. By virtue of the very high compactness parameter (L/R), copious pair production due to photon-photon collisions causes the local MECO surface temperature to always be maintained at about (mass electron)*c^2/k ~ 6 × 10^9 K independent of the external accretion rate.

Disinfo Agent
2008-Jul-22, 02:36 PM
As this paper, notes contrary to what some papers have claimed, the SGR A* observations have not proved that SGR A* has an event horizon.Which papers have claimed it did?

William
2008-Jul-23, 02:21 AM
P.S. The link in the above comment to this MECO paper did not work. This is the correct link.

http://arxiv.org/abs/astro-ph/0603746v2

Does Sgr A* Have an Intrinsic Magnetic Moment Instead of an Event Horizon? by Stanley Robertson, Darryl Leiter


In reply to Disinfo Agent's comment:


Which papers have claimed it [SRG A* my comment] did [Have an event horizon. my comment.]?


This is one of the papers that claims that the low luminosity of SGR A* shows that it is a black hole with an event horizon.

http://arxiv.org/abs/astro-ph/9706112

Advection-Dominated Accretion Model of Sagittarius A*: Evidence for a Black Hole at the Galactic Center by Ramesh Narayan et al.


Sgr A* at the Galactic Center is a puzzling source. It has a mass M=(2.5+/-0.4) x 10^6 solar masses which makes it an excellent black hole candidate. Observations of stellar winds and other gas flows in its vicinity suggest a mass accretion rate approximately few x 10^{-6} solar masses per year. However, such an accretion rate would imply a luminosity > 10^{40} erg/s if the radiative efficiency is the usual 10 percent, whereas observations indicate a bolometric luminosity <10^{37} erg/s. The spectrum of Sgr A* is unusual, with emission extending over many decades of wavelength. We present a model of Sgr A* which is based on a two-temperature optically-thin advection-dominated accretion flow. The model is consistent with the estimated mass and accretion rate, and fits the observed fluxes in the cm/mm and X-ray bands as well as upper limits in the sub-mm and infrared bands; the fit is less good in the radio below 86 GHz and in gamma-rays above 100 MeV (my bold). The very low luminosity of Sgr A* is explained naturally in the model by means of advection. Most of the viscously dissipated energy is advected into the central mass by the accreting gas, and therefore the radiative efficiency is extremely low, approximately 5 x 10^{-6}. A critical element of the model is the presence of an event horizon at the center which swallows the advected energy. The success of the model could thus be viewed as confirmation that Sgr A* is a black hole.

Disinfo Agent
2008-Jul-23, 11:07 AM
This is one of the papers that claims that the low luminosity of SGR A* shows that it is a black hole with an event horizon.The bit you quoted from the article uses neither of the terms "event horizon" or "proven".

What they cautiously say is that the model they have come up with can be 'viewed as confirmation' that Sgr A* is a black hole.