> So even if quark stars exists, they will have a maximum mass somewhere in that range
You don't know that. If the quark degeneracy pressure is high it could support far more massive objects. After all simple heat is enough to support far more massive objects (large suns easily exceed that limit).
Why would you assume, without data, that there is no other degeneracy pressure that could support such pressures?
> within a radius of less than about 10^13 meters; we know its mass is about 4 million solar masses
> The only way to pack that much mass into that small a space without an object being there that would be easily visible to our telescopes is a black hole.
That is not true. A cold object would be invisible. If the area around it is empty of mass there would not be any jets to see either.
> X-rays and gamma rays emitted by hot matter falling into the hole.
How do you know it's a black hole and not a neutron star? The jets would look identical. You can not tell that there is an event horizon.
> An object on the other side won't be able to see that object anyway; the hole will block its view.
It would "see" it gravitationally.
> Incorrect.
You say that, yet you have not explained how I'm able to see anything fall toward the black hole. Anything heading toward a black hole would (from my POV) look like it was frozen in time.
This isn't something I've made up - all scientists agree about that part. No one has ever reconciled that with how the black hole is supposed to form in the first place.
"Light from the collapsing material takes longer and longer to reach the observer, with the light emitted just before the event horizon forms delayed an infinite amount of time. Thus the external observer never sees the formation of the event horizon; instead, the collapsing material seems to become dimmer and increasingly red-shifted, eventually fading away." https://web.archive.org/web/20130526224126/http://www.imamu....
How much clearer than that can you get? And you should recognize the name of the author.
Join the black-hole deniers club and take that next step: Since we can never see any black holes form, black holes do not exist.
> No one has ever reconciled that with how the black hole is supposed to form in the first place.
Incorrect. The first scientific paper that showed how to reconcile these things was by Oppenheimer and Snyder, published in 1939. In the late 1950s through the 1970s, this subject was studied in detail in the idealized cases where exact analytical solutions exist. Since the 1980s, numerical simulations have confirmed that the key properties of those solutions remain in much more realistic cases. If you read some actual textbooks or peer-reviewed papers on GR, instead of pop science magazines and web forums, you would know all this.
Oh, wait--you did link to a peer-reviewed paper by Penrose. Have you looked at Fig. 2 of that paper and its accompanying text? It describes exactly the reconciliation that you claim doesn't exist (the model being described is basically the 1939 Oppenheimer-Snyder model in coordinates that make things easier to see than the ones O&S used).
> You don't know that. If the quark degeneracy pressure is high it could support far more massive objects.
Nope. Go read Shapiro and Teukolsky's textbook on compact states of matter. They go into excruciating mathematical detail to show that this is not true. It has to do with relativistic degeneracy, which is a general phenomenon that applies to any kind of compact state of matter.
> Why would you assume, without data, that there is no other degeneracy pressure that could support such pressures?
Because physicists have already figured out a general model that applies to all possible states of compact matter. See above.
> Run the numbers - that's about a factor of 1,000 too large to be a black hole.
You're missing the point. For a system of that mass, there is nothing else that could fit even inside a radius 1,000 times the Schwarzschild radius and remain stable for a significant period of time. For example, if there were a million stars (or neutron stars) of one solar mass each, they would not be in stable orbits; the whole system would collapse to a black hole. This has been studied in detail numerically and is part of why astronomers are highly confident that the object at the center of our galaxy is a black hole.
> A cold object would be invisible.
There would have to be on the order of a million cold objects, not just one, because of the maximum mass limit. See above.
> How do you know it's a black hole and not a neutron star?
All of the candidates I linked to are well over the maximum mass limit.
> It would "see" it gravitationally.
I'm not sure what you mean. If you mean, would an object on the other side of the hole detect the increase in mass when the first object fell in, yes, it would.
> Anything heading toward a black hole would (from my POV) look like it was frozen in time.
Not until it got very, very close to the hole. For example, in the case of the hole at the center of the galaxy, whose Schwarzschild radius is about 10 million kilometers, you could see an object fall to within well under a million kilometers of the horizon before the light emitted from it would be too redshifted to detect. (How close would depend on how low a frequency of EM radiation your detectors could detect; we can detect very low frequencies, which means my estimate above might be quite a bit larger than our actual current detection capability.)
> all scientists agree about that part
About the general fact of light from objects falling into a black hole being redshifted, yes. But I strongly doubt you have actually run the numbers to see how close an object has to get to the hole before the redshift becomes significant.
> Since we can never see any black holes form, black holes do not exist.
Faulty logic. Nor do any of the scientific sources you quote from make this claim. They know better.
You don't know that. If the quark degeneracy pressure is high it could support far more massive objects. After all simple heat is enough to support far more massive objects (large suns easily exceed that limit).
Why would you assume, without data, that there is no other degeneracy pressure that could support such pressures?
> within a radius of less than about 10^13 meters; we know its mass is about 4 million solar masses
Run the numbers - that's about a factor of 1,000 too large to be a black hole. Here's a calculator: https://space.geometrian.com/calcs/black-hole-params.php
> The only way to pack that much mass into that small a space without an object being there that would be easily visible to our telescopes is a black hole.
That is not true. A cold object would be invisible. If the area around it is empty of mass there would not be any jets to see either.
> X-rays and gamma rays emitted by hot matter falling into the hole.
How do you know it's a black hole and not a neutron star? The jets would look identical. You can not tell that there is an event horizon.
> An object on the other side won't be able to see that object anyway; the hole will block its view.
It would "see" it gravitationally.
> Incorrect.
You say that, yet you have not explained how I'm able to see anything fall toward the black hole. Anything heading toward a black hole would (from my POV) look like it was frozen in time.
This isn't something I've made up - all scientists agree about that part. No one has ever reconciled that with how the black hole is supposed to form in the first place.
Read for yourself:
http://www.astronomy.com/magazine/ask-astro/2014/11/frozen-s...
https://astronomy.stackexchange.com/questions/2441/does-matt...
Edit:
And more:
"Light from the collapsing material takes longer and longer to reach the observer, with the light emitted just before the event horizon forms delayed an infinite amount of time. Thus the external observer never sees the formation of the event horizon; instead, the collapsing material seems to become dimmer and increasingly red-shifted, eventually fading away." https://web.archive.org/web/20130526224126/http://www.imamu....
How much clearer than that can you get? And you should recognize the name of the author.
Join the black-hole deniers club and take that next step: Since we can never see any black holes form, black holes do not exist.