Argument against the existence of black holes?

[diewlasing]

I had a brief conversation with a professor of mine and he presented, in short an argument against the existence of black holes. I'm sure you've heard it or a variation of it. It goes something like this: An advisor and his student are near a black hole. They are both wearing a watch, the same watch, synchronized to the same time. The advisor doesn't like his student though. He propels his student into the black hole past the event horizon. On the advisor's watch, he sees the student fall into the black hole and die in a finite amount of time. But the student going deeper and deeper into the black hole, the gravity becomes immense, and time slows to such a degree it takes him an infinite time to fall all the way in. Mind you, he has gone all the way past the event horizon. Thoughts?

 

[Jonathan Scott]

The advisor does not actually "see" what is happening, but rather sees increasingly delayed (and red-shifted) images of what was happening earlier. However, if he calculates the student's location and time based on those images and extrapolates forward in time, he will calculate that in his own frame of reference, the student would have reached the event horizon in a finite time. The contradiction is therefore the result of a not very meaningful mathematical calculation, rather than an actual observation.

This is in many ways just another example of the way in which relativity means that different observers observe the same events, but assign different locations and times to them in different frames of reference.

However, I personally still think black holes are probably nonsense for different reasons. Even if GR remains accurate in such extreme cases, Einstein's equations do not uniquely determine the physical radial coordinate without additional boundary conditions, and when Karl Schwarzschild himself first presented his solution (in a paper available in translation at arXiv:physics/9905030), he used a different coordinate for the coordinate distance to the Euclidean origin and his "r" coordinate was merely a mathematical convenience for simpler calculation, valid only for r > 2Gm.

So far, I've not seen any totally convincing proof either way, although I've seen some surprisingly heated opinions where people claim in both directions that it's obvious - given their own personal physical interpretation of some undeniable mathematical fact. On the basis of simplicity, I'm inclined to accept Karl Schwarzschild's own model, which doesn't include black holes, but there could be some argument that would convince me otherwise.

 

[mathman]

It looks to me like the time sensations have been switched. The outside observer sees the infalling object take an infinite amount of time to fall in, while the person falling in takes a finite amount of time to pass the event horizon and get killed.

There seems to be much observational evidence for black hole existence, particularly gigantic (millions to billions of solar mass) objects at the center of galaxies.

 

[Jonathan Scott]

There seems to be much observational evidence for black hole existence, particularly gigantic (millions to billions of solar mass) objects at the center of galaxies.

That is evidence for black holes only if you assume (a) that GR still holds in those cases and (b) that Hilbert's reinterpretation of the Schwarzschild radial coordinate as a physical radius is meaningful.

Note for example that if GR is right but Hilbert was wrong, then such objects would be not-quite-black but incredibly red-shifted and compact, but they would for example be able to have significant intrinsic magnetic fields, as they would not be susceptible to the "no hair" theorem. Many black hole candidates show signs of strong magnetic fields, and although it is plausible that these could arise from the accretion disk, there is experimental evidence that the properties of the observed fields do not correlate well with the properties of the accretion disk, for example in the case of the gravitationally lensed quasar Q0957+561, where the magnetic field seems to be associated with the central object. This evidence has been used to promote another alternative theory to black holes known as a MECO (Magnetospheric Eternally Collapsing Object), but it also supports GR with Karl Schwarzschild's original interpretation of the radial coordinate.

 

[Margiani]

Each black hole is remnant, cooled nucleus of an exploded star and has nuclear density.

 

[George Jones]

Each black hole is remnant, cooled nucleus of an exploded star and has nuclear density.

If a black hole is formed during stellar collapse, then, according to an observer falling with the surface of the remnant, the density of the remnant rapidly exceeds nuclear density.

 

[Margiani]

Falling matter on the black hole produces micro-quasar or quasar. Connected to the size of black hole.

 

[George Jones]

Falling matter on the black hole produces micro-quasar or quasar. Connected to the size of black hole.

Could you give a reference?

And what does this have to do with the density of the remnant?

 

[Margiani]

A remnant density is decreasing.
go through Google about micro-quasars.
in the case of quasars of course the event is same and large-scaled

 

[George Jones]

A remnant density is decreasing.

As the black hole forms, the mass of the remnant increases

go through Google about micro-quasars.
in the case of quasars of course the event is same and large-scaled

This is not a satisfactory response. Let me remind you of some of the rules

https://www.physicsforums.com/showthread.php?t=5374

here at Physics Forums,

Overly Speculative Posts: One of the main goals of PF is to help students learn the current status of physics as practiced by the scientific community; accordingly, Physicsforums.com strives to maintain high standards of academic integrity. There are many open questions in physics, and we welcome discussion on those subjects provided the discussion remains intellectually sound. It is against our Posting Guidelines to discuss, in most of the PF forums, new or non-mainstream theories or ideas that have not been published in professional peer-reviewed journals or are not part of current professional mainstream scientific discussion. Posts deleted under this rule will be accompanied by a private message from a Staff member, and, if appropriate, an invitation to resubmit the post in accordance with our Independent Research Guidelines. Poorly formulated personal theories, unfounded challenges of mainstream science, and overt crackpottery will not be tolerated anywhere on the site. Linking to obviously "crank" or "crackpot" sites is prohibited.

 

[George Jones]

However, I personally still think black holes are probably nonsense for different reasons. Even if GR remains accurate in such extreme cases, Einstein's equations do not uniquely determine the physical radial coordinate without additional boundary conditions, and when Karl Schwarzschild himself first presented his solution (in a paper available in translation at arXiv:physics/9905030), he used a different coordinate for the coordinate distance to the Euclidean origin and his "r" coordinate was merely a mathematical convenience for simpler calculation, valid only for r > 2Gm.

So far, I've not seen any totally convincing proof either way, although I've seen some surprisingly heated opinions where people claim in both directions that it's obvious - given their own personal physical interpretation of some undeniable mathematical fact. On the basis of simplicity, I'm inclined to accept Karl Schwarzschild's own model, which doesn't include black holes, but there could be some argument that would convince me otherwise.

These ideas have been thoroughly discredited; see

https://www.physicsforums.com/showthread.php?t=141985&highlight=Abrams

http://arxiv.org/abs/gr-qc/0608033.

 

[Count Iblis]

A better argument against the formation of event horizons in gravitational collapse is given here:

http://arxiv.org/abs/gr-qc/0609024

See Section 7 on page 10 and further.

 

[George Jones]

A better argument against the formation of event horizons in gravitational collapse is given here:

http://arxiv.org/abs/gr-qc/0609024

See Section 7 on page 10 and further.

Better in that this paper doesn't make undergraduate mistakes, but it is still highly speculative and controversial, and has yet to be accepted by the physics community. Also this paper is not classical, i.e., its claims are based on quantum effects. I have mentioned this paper on Physics Forums several times, e.g.,

https://www.physicsforums.com/showthread.php?p=1534827#post1534827.

 

[Jonathan Scott]

These ideas have been thoroughly discredited; see

https://www.physicsforums.com/showthread.php?t=141985&highlight=Abrams

http://arxiv.org/abs/gr-qc/0608033.

George, I don't agree. Neither that thread nor the article justifies the use of Hilbert's assumption about the radial coordinate; they merely find fault with other aspects of the relevant papers, and I find the extremely defensive and abusive nature of the responses (especially from "tessel" quite extraordinary in itself).

I've answered the same point in more detail in another thread at https://www.physicsforums.com/showpost.php?p=1884298&postcount=6

 

[unedjoocated]

On the advisor's watch, he sees the student fall into the black hole and die in a finite amount of time. But the student going deeper and deeper into the black hole, the gravity becomes immense, and time slows to such a degree it takes him an infinite time to fall all the way in. Mind you, he has gone all the way past the event horizon. Thoughts?

Wouldnt this be the oposite? The professor would see the student get closer and closer to the black hole but his light would slow down as gravity started to effect it. Eventually the light from the student would slow to a stop as he reached the event horizon and the professor would never actually see the student go into the black hole. He would only see the students light lingering just ouside the event horizon. The student on the other hand would approach the event horizon and eventually be sucked in and killed, yet to him his watch still appears to be running normal even though time is altered by the mass of the black hole. I am not an expert in physics or math, but i am doing research for an argumentative speech over black holes and i am having trouble finding points and counterpoints for this matter. I've seen that black holes are science fact now, but I've also seen that their existence is still a matter of speculation. Can anyone help me disprove them or prove them in lamens terms... while keeping in mind that i know practially nothing about physics or math. And my only real knowledge in either subject is what i can picture in my mind, not prove through equations.

..be gentle >.<

 

[twofish-quant]

Even if GR remains accurate in such extreme cases, Einstein's equations do not uniquely determine the physical radial coordinate without additional boundary conditions

So?

If you put in additional boundary conditions you still get a collapse to a black hole.

So far, I've not seen any totally convincing proof either way, although I've seen some surprisingly heated opinions where people claim in both directions that it's obvious - given their own personal physical interpretation of some undeniable mathematical fact.

There are also two different statements:

1) any collapsing object will turn into a black home
2) black holes don't exist

1) is a somewhat controversial, but there is no way I can see around 2). You can solve Einstein's equations using something other than schwarzchild conditions and you get a collapse to a singularity.

On the basis of simplicity, I'm inclined to accept Karl Schwarzschild's own model, which doesn't include black holes, but there could be some argument that would convince me otherwise.

Simple,

Do a coordinate transformation to Kruskal-Szekeres coordinates

see

http://en.wikipedia.org/wiki/Kruskal-Szekeres_coordinates

 

[twofish-quant]

That is evidence for black holes only if you assume (a) that GR still holds in those cases and (b) that Hilbert's reinterpretation of the Schwarzschild radial coordinate as a physical radius is meaningful

a) yes b) no.

In fact when you do black holes, there is interpretation as a "physics radius". R is just a coordinate, and you can use any other,

Note for example that if GR is right but Hilbert was wrong, then such objects would be not-quite-black but incredibly red-shifted and compact, but they would for example be able to have significant intrinsic magnetic fields, as they would not be susceptible to the "no hair" theorem.

Not true. Kip Thorne worked this out in the 1970's, and wrote a book about this called the membrane paradigm. To summarize, because the time coordinate slows down, you can treat the surface of a black hole "as if" it as a conducting surface at which you can attach a magentic field.

Many black hole candidates show signs of strong magnetic fields, and although it is plausible that these could arise from the accretion disk, there is experimental evidence that the properties of the observed fields do not correlate well with the properties of the accretion disk

That's because the magnetic field is generated by a dynamo centered on the black hole. See Kip Thorne. I really don't take any of the MECO papers seriously, because they ignore Thorne's work in the 1970's. Unless someone explains why Thorne's arguments and mechanisms don't work, I don't see any reason for the MECO speculation.

 

[FtlIsAwesome]

Welcome to PF, unedjoocated.

unedjoocated, twofish, I'm not sure if you've noticed, but this thread is ~3 years old, so some of the information may be outdated.