Drunk on Black Holes

[MigL]

The event horizon, no matter what co-oedinate system is used, is a strictly mathematical construct. THERE IS NOTHING ACTUALLY THERE !

 

Decraig, you need to consider the physicality of the situation not just the mathematics. You say you have 30 yrs experience with the mathematics describing the situation and I say that there is no force or mechanism that can stop the collapse of a massive star once gravity overcomes nuclear radiation pressure and electron and neutron degeneracy.

 

So again I ask you, not for mathematical proof, which may or may not be valid ( we have estabilished that GR is only valid within certain limits, have we not ? ), but for physical options.

[Endercreeper01]

Is this an argument saying that nothing can fall in to a black hole or that nothing can escape a black hole?

It is an argument that nothing can fall into a black hole with respect to a distant observer and with respect to the object falling into the black hole.

[decraig]

The event horizon, no matter what co-oedinate system is used, is a strictly mathematical construct. THERE IS NOTHING ACTUALLY THERE !

 

Decraig, you need to consider the physicality of the situation not just the mathematics. You say you have 30 yrs experience with the mathematics describing the situation and I say that there is no force or mechanism that can stop the collapse of a massive star once gravity overcomes nuclear radiation pressure and electron and neutron degeneracy.

 

So again I ask you, not for mathematical proof, which may or may not be valid ( we have estabilished that GR is only valid within certain limits, have we not ? ), but for physical options.

If you don't like mathematical constructions, don't defer to general relativity. Now that you throw away mathematics, which is what you are doing, what are you going to do?

 

You also think, in the Newtonian manner that, that collapse to a black hole is inescapable. Get over Newton.

Edited January 20, 2014 by decraig

[ajb]

It is an argument that nothing can fall into a black hole with respect to a distant observer and with respect to the object falling into the black hole.

Then your argument is not quite right. The part about from the perspective of distant observer is correct as it takes "an infinite amount of time to see the in falling object pass the event horizon". Loosely, you equate the coordinate time with the proper time of a distant observer. But this is different to the proper time as measured by the in falling particle. The particle crosses the event horizon in finite time as defined by its proper time. In fact nothing special happens when it crosses the event horizon, the particle will not notice anything happen.

 

The same applies for the formation of black holes. It only takes forever if we define the time taken as that of a distant observer and his observations of the forming black hole via out coming light rays.

[davidivad]

 

my appologies.

from your postings, i got the strangest impression.

i think that keeping a level head is important for getting to know the players in your field.

 

in my simplistic phrasing, you have not shown how you reach your conclusion in a complete manner.

please, humor me with some math.

 

without a response, i must then assume you cannot do the math.

i can only logically assume you have read a few articles and stitched them into an incomplete idea.

this is where math comes in.

that is a shame as i might have been able to help you realise your idea with graphics.

[Endercreeper01]

Then your argument is not quite right. The part about from the perspective of distant observer is correct as it takes "an infinite amount of time to see the in falling object pass the event horizon". Loosely, you equate the coordinate time with the proper time of a distant observer. But this is different to the proper time as measured by the in falling particle. The particle crosses the event horizon in finite time as defined by its proper time. In fact nothing special happens when it crosses the event horizon, the particle will not notice anything happen.

 

The same applies for the formation of black holes. It only takes forever if we define the time taken as that of a distant observer and his observations of the forming black hole via out coming light rays.

Relative to the particle, the black hole is accelerating towards it with the same acceleration as the particle. All accelerating reference frames are equivalent, so the black hole appears to experience time dilation relative to the particle. When [latex]R_s=r[/latex], time freezes for the particle with respect to a distant observer. When the particle reaches the event horizon, the black hole appears to have the same acceleration as the particle with respect to the particle. So, shouldn't the black hole experience time dilation with respect to the particle?

[Strange]

All accelerating reference frames are equivalent

 

Except they are not. Inertial reference frames are equivalent because there is no way of distinguishing between you moving relative to a stationary object or that object moving relative to you. However, you can always tell if you are accelerating: you will feel a force.

 

Also, I'm not sure how that is relevant to ajb's point: the time dilation seen by an external observer is due to the gravitational field of the black hole, not acceleration. And, again, that is just as seen by a distant observer. From the point of view of someone free-falling through the event horizon, or someone stationary close to the event horizon, it takes finite time to cross the event horizon.

[Spyman]

I guess you're irritated because I haven't directly answered your posts. Understandable.

 

Completely wrong. My dislike of black holes reflects my dislike of pseudo science. Perhaps you might examine your own objectivity if you have the skills in physics, or the manner in which you defer to authority if you don't.

 

So what do you have as best evidence that I already haven't shot down? Post any website or article written in English.

No, I am not irritated, I simply question to your intent with this thread, because you ask for evidence of black holes, but when presented with such you react very negatively. This is again obvious in your reply to me, where you keep on questioning my skills and whether I follow authority without thinking for myself.

 

If all you want is to vent off some steam and bash on the science channel, then I can understand that, but if you are trying to achieve something else, you should stop beat around the bush and come clear with a good explanation of what you really want.

 

Claims that scientific consensus is "pseudo science" and that their "followers" are like religious belivers only damages your own credibility.

 

So far I don't consider you to have gotten even close to shot down the scientific consensus in the matter of black holes. Further more I don't have to provide evidence for established mainstream physics, that has already been done by professional scientists in that area of research. If you on the other hand want to disprove their work, then you are the one in need of providing evidence, and so far your evidence is insufficient.

[Endercreeper01]

 

Except they are not. Inertial reference frames are equivalent because there is no way of distinguishing between you moving relative to a stationary object or that object moving relative to you. However, you can always tell if you are accelerating: you will feel a force.

 

 

Oh, just wondering.

[decraig]

So far I don't consider you to have gotten even close to shot down the scientific consensus in the matter of black holes. Further more I don't have to provide evidence for established mainstream physics, that has already been done by professional scientists in that area of research. If you on the other hand want to disprove their work, then you are the one in need of providing evidence, and so far your evidence is insufficient.

Reference, please,

[Endercreeper01]

My dislike of black holes reflects my dislike of pseudo science

Some claims involving black holes may be pseudoscience, but black holes themselves are not.

Black holes have a mathematical framework surrounding them, such as the Schwarzschild metric:

[latex]ds^2=\left(1-\frac{2GM}{rc^2}\right)dt^2-\left(1-\frac{2GM}{rc^2}\right)^{-1}dr^2-r^2d\theta ^2 - r^2 sin^2\theta \ d\phi ^2[/latex]

and the event horizon radius for a Schwarzschild black hole (Schwarzschild radius) :

[latex]R_s=\frac{2GM}{c^2}[/latex]

Pseudoscience has no mathematics (or no scientific evidence for mathematical claims), unlike black holes.

There is lots of evidence for black holes, such as supernovas. If a star is massive enough, it will collapse into a supernova. The matter left behind will have to compress into a black hole, and that is what happens.

[Spyman]

 

So far I don't consider you to have gotten even close to shot down the scientific consensus in the matter of black holes. Further more I don't have to provide evidence for established mainstream physics, that has already been done by professional scientists in that area of research. If you on the other hand want to disprove their work, then you are the one in need of providing evidence, and so far your evidence is insufficient.

Reference, please,

 

I shouldn't really have to provide a reference on scientific consensus in the matter of black holes, but here you go:

 

"Objects whose gravity fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958. Long considered a mathematical curiosity, it was during the 1960s that theoretical work showed black holes were a generic prediction of general relativity. The discovery of neutron stars sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.

 

Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may form. There is general consensus that supermassive black holes exist in the centers of most galaxies."

http://en.wikipedia.org/wiki/Black_hole

 

 

Or if you requested a reference that scientific work has been done to provide evidence of black holes:

 

"High Proper Motion Stars in the Vicinity of Sgr A*: Evidence for a Supermassive Black Hole at the Center of Our Galaxy

Over a two year period (1995-1997), we have conducted a diffraction-limited imaging study at 2.2 microns of the inner 6"x6" of the Galaxy's central stellar cluster using the Keck 10-m telescope. The K band images obtained reveal a large population of faint stars. We use an unbiased approach for identifying and selecting stars to be included in this proper motion study, which results in a sample of 90 stars with brightness ranging from K=9-17 and velocities as large as 1,400+-100 km/sec. Compared to earlier work (Eckart et al. 1997; Genzel et al. 1997), the source confusion is reduced by a factor of 9, the number of stars with proper motion measurement in the central 25 arcsec^2 of our galaxy is doubled, and the accuracy of the velocity measurements in the central 1 arcsec^2 is improved by a factor of 4. The peaks of both the stellar surface density and the velocity dispersion are consistent with the position of the unusual radio source and blackhole candidate, Sgr A*, suggesting that Sgr A* is coincident (+-0."1) with the dynamical center of the Galaxy. As a function of distance from Sgr A*, the velocity dispersion displays a falloff well fit by Keplerian motion about a central dark mass of 2.6(+-0.2)x10^6 Mo confined to a volume of at most 10^-6 pc^3, consistent with earlier results. Although uncertainties in the measurements mathematically allow for the matter to be distributed over this volume as a cluster, no realistic cluster is physically tenable. Thus, independent of the presence of Sgr A*, the large inferred central density of at least 10^12 Mo/pc^3, which exceeds the volume-averaged mass densities found at the center of any other galaxy, leads us to the conclusion that our Galaxy harbors a massive central black hole."

http://arxiv.org/abs/astro-ph/9807210

[MigL]

Don't put words in my mouth decraig. I did not mention Newton and I understand the math of GR quite well. I also like to believe I understand some Physics. All Relativity does is tell us how the same event 'looks' to different observers or frames. The fact that gravitational collapse 'seems' to not happen in a non-local frame does not mean it doesn't happen in a local frame. The local observer does pass through the mathematical point of no return ( event horizon ) and on to the singularity. Now I would claim that this singularity is non-physical but you having faith in the math of GR, must consider it real.

[decraig]

 

without a response, i must then assume you cannot do the math.

i can only logically assume you have read a few articles and stitched them into an incomplete idea.

this is where math comes in.

that is a shame as i might have been able to help you realise your idea with graphics.

That would be a little too sleezy for my tastes

[davidivad]

it was not my intent to offend you.

 

my intent was to get your math out onto a page for critique.

while i know more math than the average person, i lack accuracy. i often forget small yet crucial things. however, there are people that are on this site whom have far superior math skills compared to me.

they are a resource so use them.

 

it is not how smart you are that gets you through life but how well you use your resources.

[decraig]

davidivad.

 

Lets start over. If you want to make some interesting plots you can start here. http://en.wikipedia.org/wiki/Schwarzschild_metric

 

Plot the [math]dt^2[/math] and [math]dx^2[/math] coefficients as a function of [math]r/r_{s}[/math].

 

Even more interesting, in the way of testing my assertions, try looking at http://arxiv.org/abs/gr-qc/0201037.

 

I haven't yet read it. The author claims to have some interesting coordinates that are singularity-free at [math]r_s[/math]. I have little doubt that he does---but I just haven't read it.

 

This really is an issue in modern mythology. It's like the telephone game--each retelling of the story embellishes the original message--even among professionals. It is driven by the human desire to reaquire the mysterious, lost when most of the scientific community embraced atheism.

Edited January 21, 2014 by decraig

[Strange]

There is some interesting background on the Painleve-Gullstrand coordinates on Wikipedia. I hadn't realised that Painleve tried to argue that they showed GR to be wrong/incomplete and that Einstein rejected it as a solution to the EFE. (It wasn't until later that Lemaitre showed they were equivalent to to Schwarzschild coordinates.)

http://en.wikipedia.org/wiki/Gullstrand%E2%80%93Painlev%C3%A9_coordinates

 

I think the Schwarzschild metric is the only solution to the Einstein Field Equations that has a singularity at the Schwarzschild radius (but I could be wrong). All the other commonly used coordinates (P-G, Eddington–Finkelstein, Kruskal–Szekeres, Lemaitre) avoid it.

[imatfaal]

davidivad.

 

Lets start over. If you want to make some interesting plots you can start here. http://en.wikipedia.org/wiki/Schwarzschild_metric

 

Plot the [math]dt^2[/math] and [math]dx^2[/math] coefficients as a function of [math]r/r_{s}[/math].

 

Even more interesting, in the way of testing my assertions, try looking at http://arxiv.org/abs/gr-qc/0201037.

 

I haven't yet read it. The author claims to have some interesting coordinates that are singularity-free at [math]r_s[/math]. I have little doubt that he does---but I just haven't read it.

 

This really is an issue in modern mythology. It's like the telephone game--each retelling of the story embellishes the original message--even among professionals. It is driven by the human desire to reaquire the mysterious, lost when most of the scientific community embraced atheism.

 

No it is not modern mythology - you are merely using the wrong tools; no one denies that schwarzchild space time geometry clearly hits problems when r=2M - ie at the Event Horizon where [latex]g_{tt}[/latex] becomes zero and [latex]g_{\tau \tau}[/latex] becomes infinite. This was originally thought to be evidence of a physical singularity at the EH - but Eddington showed that it was merely an artifact of the coordinate system being used - ie Schwarzchild Coordinates.

 

Tell you what - plot [latex]g_{\phi \phi}[/latex] with changing [latex]\theta[/latex] You will notice that a simple sphere hits problems at poles due to this choice of coordinate system - again this is purely mathematical and not physical.

 

You need to use an alternative method of describing your point in space. As has been repeated ad nauseam you need to use Eddington-Finkelstein. http://en.wikipedia.org/wiki/Eddington%E2%80%93Finkelstein_coordinates Please read up on this before repeating your fallacy.

[decraig]

There is some interesting background on the Painleve-Gullstrand coordinates on Wikipedia. I hadn't realised that Painleve tried to argue that they showed GR to be wrong/incomplete and that Einstein rejected it as a solution to the EFE. (It wasn't until later that Lemaitre showed they were equivalent to to Schwarzschild coordinates.)

http://en.wikipedia.org/wiki/Gullstrand%E2%80%93Painlev%C3%A9_coordinates

 

I think the Schwarzschild metric is the only solution to the Einstein Field Equations that has a singularity at the Schwarzschild radius (but I could be wrong). All the other commonly used coordinates (P-G, Eddington–Finkelstein, Kruskal–Szekeres, Lemaitre) avoid it.

Thanks, for that. Add electric charge and you get the Reissner-Nordstrom metric, http://en.wikipedia.org/wiki/Reissner%E2%80%93Nordstr%C3%B6m_metric, with two critical radii.

 

 

Reissner–Nordström

Edited January 22, 2014 by decraig

[imatfaal]

Thanks, for that. Add electric charge and you get the Reissner-Nordstrom metric, http://en.wikipedia.org/wiki/Reissner%E2%80%93Nordstr%C3%B6m_metric, with two critical radii.

 

 

Reissner–Nordström

 

No - that is Schwarzchild plus charge; or more accurately R-N in the limiting scenario where charge goes to zero reduces to the Schwarzchild metric( and for an uncharged BH you would still get a mathematical singularity at the EH). E-F coordinates are more complex in that they play around with t and actually take on a different form for ingoing particles and outgoing - there is no doubt that S'child are more intuitive, beautiful etc - but they just do not work at the EH

[decraig]

 

No - that is Schwarzchild plus charge; or more accurately R-N in the limiting scenario where charge goes to zero reduces to the Schwarzchild metric( and for an uncharged BH you would still get a mathematical singularity at the EH). E-F coordinates are more complex in that they play around with t and actually take on a different form for ingoing particles and outgoing - there is no doubt that S'child are more intuitive, beautiful etc - but they just do not work at the EH

Based upon these confused remarks, I don't think physics is your calling. You are not positively contributing to this thread but just trying to win an argument without supplying merit. This repeated invokation of Eddington-Finkelstein coordinates is immaterial. Per canon, mapping to EF coordinates does not affect physical results. The coordinate map between the Schwarzschild and EF charts is invertible over the coordinates range involved. Look it up. EF yields the same time for black hole formation as S. This is introductory level general relativity.

 

If you are versed in elementary general relativity you will be able to name the canon to which I referred. This is a challenge to your credibility.

Edited January 23, 2014 by decraig

[imatfaal]

Based upon these confused remarks, I don't think physics is your calling. You are not positively contributing to this thread but just trying to win an argument without supplying merit. This repeated invokation of Eddington-Finkelstein coordinates is immaterial. Per canon, mapping to EF coordinates does not affect physical results. The coordinate map between the Schwarzschild and EF charts is invertible over the coordinates range involved. Look it up. EF yields the same time for black hole formation as S. This is introductory level general relativity.If you are versed in elementary general relativity you will be able to name the canon to which I referred. This is a challenge to your credibility.

 

 

 

My credibility is already completely shot to pieces - so I have no need to play silly games with trolls. I have read quite recently Sean Carroll's notes on GR and that seems similar; but I am sure you are referring to something far more abstruse. The fact that EF coordinates are invertible - is one of the major clues that the singularity is non-physical; a fact you still seem to be missing.

 

So which bit is confused?

 

No - that is Schwarzchild plus charge; or more accurately R-N in the limiting scenario where charge goes to zero reduces to the Schwarzchild metric( and for an uncharged BH you would still get a mathematical singularity at the EH).

 

Do you think this is wrong? Makes sense to me and I am pretty sure I am correct.

 

E-F coordinates are more complex in that they play around with t and actually take on a different form for ingoing particles and outgoing

Perhaps a little jokey - but still correct. EF coordinates introduces tortoise coordinates and changed coordinate time - this gives different solutions to radial null curves for infalling and outfalling

 

- there is no doubt that S'child are more intuitive, beautiful etc - but they just do not work at the EH

The bit you keep arguing - and no matter how insulting, trollish, and stubborn your posts become, this is the crux of the matter from your first post onwards. And it remains correct.

 

You are quite right that "mapping to EF coordinates does not affect physical results" ; so why in heaven do you not understand that this shows incontrovertibly that the Schild coordinate singularity at the event horizon must be non-physical. If it disappears in EF or Kruskal coordinates - and a coordinate change cannot affect physical results - then the only conclusion is that it must be non-physical!

[decraig]

 

 

 

My credibility is already completely shot to pieces - so I have no need to play silly games with trolls. I have read quite recently Sean Carroll's notes on GR and that seems similar; but I am sure you are referring to something far more abstruse. The fact that EF coordinates are invertible - is one of the major clues that the singularity is non-physical; a fact you still seem to be missing.

 

So which bit is confused?

 

 

Do you think this is wrong? Makes sense to me and I am pretty sure I am correct.

 

Perhaps a little jokey - but still correct. EF coordinates introduces tortoise coordinates and changed coordinate time - this gives different solutions to radial null curves for infalling and outfalling

 

The bit you keep arguing - and no matter how insulting, trollish, and stubborn your posts become, this is the crux of the matter from your first post onwards. And it remains correct.

 

You are quite right that "mapping to EF coordinates does not affect physical results" ; so why in heaven do you not understand that this shows incontrovertibly that the Schild coordinate singularity at the event horizon must be non-physical. If it disappears in EF or Kruskal coordinates - and a coordinate change cannot affect physical results - then the only conclusion is that it must be non-physical!

pure nonsense

Edited January 23, 2014 by decraig

[hypervalent_iodine]

!

Moderator Note

decraig, if you think that imatfaal is incorrect, address exactly where it is that his information falls short. Do not simply wave off the post by insulting his intelligence or simply saying that is nonsense - especially when it doesn't actually appear to be nonsense at all.

 

Also, if you are going to report someone for apparently insulting you - though I truly don't see it - perhaps you should try and and avoid the same behavior?

 

Lastly, this thread is getting tiresome and I think people are quickly losing patience with your inability to consider the information that is actually out there refuting your ideas. People have linked you papers and they have provided you with good information. You cannot keep ignoring them because you don't like it or you don't have access to the papers that people have linked you and if you do, then expect this to be closed (as I have already warned you).

[decraig]

[modnote] decraig, if you think that imatfaal is incorrect, address exactly where it is that his information falls short. Do not simply wave off the post by insulting his intelligence or simply saying that is nonsense - especially when it doesn't actually appear to be nonsense at all.

 

Also, if you are going to report someone for apparently insulting you - though I truly don't see it - perhaps you should try and and avoid the same behavior?

 

Lastly, this thread is getting tiresome and I think people are quickly losing patience with your inability to consider the information that is actually out there refuting your ideas. People have linked you papers and they have provided you with good information. You cannot keep ignoring them because you don't like it or you don't have access to the papers that people have linked you and if you do, then expect this to be closed (as I have already warned you). [/modnote]

I have, many times already. And I just keep on getting false information, red herrings consisting of either irrelevant information of references that even contradict the claim made of them. Look for yourself.

 

As to your second remark that I have put in bold, this is far from correct. Please show me an example where I have done this. Produce this information that is "actually out there".

 

This was the intent of this thread, and no one have yet manged to produced it, yet insist that it is there. If unsupported claims are the stock in trade in this forum, why call it a science forum.

 

I have enumerated approximately 6 points, unverifed that could falsify a conjecture of non-formation of black holes. I haven't seen any of these points raised.

 

 

 

Some claims involving black holes may be pseudoscience, but black holes themselves are not.

Black holes have a mathematical framework surrounding them, such as the Schwarzschild metric:

[latex]ds^2=\left(1-\frac{2GM}{rc^2}\right)dt^2-\left(1-\frac{2GM}{rc^2}\right)^{-1}dr^2-r^2d\theta ^2 - r^2 sin^2\theta \ d\phi ^2[/latex]

and the event horizon radius for a Schwarzschild black hole (Schwarzschild radius) :

[latex]R_s=\frac{2GM}{c^2}[/latex]

Pseudoscience has no mathematics (or no scientific evidence for mathematical claims), unlike black holes.

There is lots of evidence for black holes, such as supernovas. If a star is massive enough, it will collapse into a supernova. The matter left behind will have to compress into a black hole, and that is what happens.

Notice that the Schwarzschild metric is invariant with time (it doesn't change over time).

 

This metric solution is insufficient evidence of physical black holes formatationbecause to make one, the metric has to change with time. It looks good on paper and the drawings are attractive, but the map is not the territory.

 

Do you see that you have to have a means of formation before you can justify models of existent black holes, or alternatively supply experimental evidence?

 

I've already addressed this.

I shouldn't really have to provide a reference on scientific consensus in the matter of black holes, but here you go:

 

"Objects whose gravity fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958. Long considered a mathematical curiosity, it was during the 1960s that theoretical work showed black holes were a generic prediction of general relativity. The discovery of neutron stars sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.

 

Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may form. There is general consensus that supermassive black holes exist in the centers of most galaxies."

http://en.wikipedia.org/wiki/Black_hole

 

 

Or if you requested a reference that scientific work has been done to provide evidence of black holes:

 

"High Proper Motion Stars in the Vicinity of Sgr A*: Evidence for a Supermassive Black Hole at the Center of Our Galaxy

Over a two year period (1995-1997), we have conducted a diffraction-limited imaging study at 2.2 microns of the inner 6"x6" of the Galaxy's central stellar cluster using the Keck 10-m telescope. The K band images obtained reveal a large population of faint stars. We use an unbiased approach for identifying and selecting stars to be included in this proper motion study, which results in a sample of 90 stars with brightness ranging from K=9-17 and velocities as large as 1,400+-100 km/sec. Compared to earlier work (Eckart et al. 1997; Genzel et al. 1997), the source confusion is reduced by a factor of 9, the number of stars with proper motion measurement in the central 25 arcsec^2 of our galaxy is doubled, and the accuracy of the velocity measurements in the central 1 arcsec^2 is improved by a factor of 4. The peaks of both the stellar surface density and the velocity dispersion are consistent with the position of the unusual radio source and blackhole candidate, Sgr A*, suggesting that Sgr A* is coincident (+-0."1) with the dynamical center of the Galaxy. As a function of distance from Sgr A*, the velocity dispersion displays a falloff well fit by Keplerian motion about a central dark mass of 2.6(+-0.2)x10^6 Mo confined to a volume of at most 10^-6 pc^3, consistent with earlier results. Although uncertainties in the measurements mathematically allow for the matter to be distributed over this volume as a cluster, no realistic cluster is physically tenable. Thus, independent of the presence of Sgr A*, the large inferred central density of at least 10^12 Mo/pc^3, which exceeds the volume-averaged mass densities found at the center of any other galaxy, leads us to the conclusion that our Galaxy harbors a massive central black hole."

http://arxiv.org/abs/astro-ph/9807210

I agree. You should not provide a consensus--provide evidence or scholarly papers instead. The ideal of science appeals to evidence not authority.

 

As to your reference I have put in bold: Have you read the article. Can you cite the section where they provide distinguish evidence between BHs and highly collapsed matter? Is it even addressed?

 

Evidence is evidence, but distinguishing evidence is what is require here.

Don't put words in my mouth decraig. I did not mention Newton and I understand the math of GR quite well. I also like to believe I understand some Physics. All Relativity does is tell us how the same event 'looks' to different observers or frames. The fact that gravitational collapse 'seems' to not happen in a non-local frame does not mean it doesn't happen in a local frame. The local observer does pass through the mathematical point of no return ( event horizon ) and on to the singularity. Now I would claim that this singularity is non-physical but you having faith in the math of GR, must consider it real.

I'm glade you know GR quite well.

 

All coordinate charts are nonlocal frames at points over their domain. By putting quotes around 'seems' are you implying that coordinate charts should not be used describe physics?

 

Interesting. Do think that all charts with singular points are nonphysical?

Edited January 24, 2014 by decraig