Do black holes really exist in the real world or are they just virtual objects

BHs/Dark Stars are predicted by both Newtonian mechanics and GR, and both require an horizon where the escape velocity of light is exceeded.
What is beyond the EH is neither here nor there in this particular context and debate.
GR but, being the more precise/ accurate model would hold preference in the eyes of most scientists.

Our observations and knowledge of physics logically leads us to assume that GR BHs certainly do exist, or at least the Newtonian variety we call a Dark Star.
To deny that existence one must logically show the scientific world of Cosmology, some other entity/phenomena that would cause the effects on space/time and matter/energy that we actually do see....including accretion disks disappearing into a cosmological black abyss.
Can you do that?


Oh, and remember...
Science is what you know. Philosophy is what you don't know.
Bertrand Russell (1872-1970) English philosopher, mathematician.

 

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Ahh! Paddoboy gets it! I do not deny that dark stars exist right now.

 

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Great! We're agreed then!: Black holes, formerly known as "dark stars" exist and Cygnus X-1 is one.

This is a momentous event in the history of the internet; the first time ever that an argument has been resolved. I feel privileged to have been a part of it and thank you, RJBeery, for joining me in making history!

 

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Good work, remembering of course that both Newtonian Dark Stars and BHs have an EH from beyond which we receive no information, and they are from an observation point of view one and the same.

A dark star is a theoretical object compatible with Newtonian mechanics that, due to its large mass, has a surface escape velocity that equals or exceeds the speed of light.
WIKI:

A black hole is a region of spacetime from which gravity prevents anything, including light, from escaping.[1] The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole, there is a mathematically defined surface called an event horizon that marks the point of no return.
WIKI:

 

That isn't quite true actually. Being based on Newtonian gravity means predicted behavior of dark stars would not agree with observations such as stellar aberration/gravitational lensing.

That's neither here not there though; the choice to discard one name in favor of a new one when the theory failed is an arbitrary decision having nothing to do with the fact that these objects that were formerly known as dark stars and are now known as black holes exist. We didn't for example, discard the name "gravity" when it was discovered that Newton's theory of gravity failed, but we could have. Gravity exists now, and it existed before Einstein, despite the fact that our understanding of how it works has changed. So too for dark stars/black holes.

 

That is philosophical claptrap.......
As I said previously, the BH is established by firstly the EH [both Dark Stars and GR BH have them] and secondly by the effects on matter/energy and space/time in their vicinity.
The Singularity predicted by the GR BH, is both a mathematical concept where models and maths fail, and more then likely a physical region established at the quantum/Planck level...
A Singularity need not be infinite in itself, although it may lead to infinite quantities.

You "New Years Eve" analogy is irrelevant and misses the point entirely..

 

Yeah, OK, I do see your point...You speak of space/time warping and curvature which isn't a part of Newtonian???
My point is though [for the sake of this argument] that if people see the need to argue about whether it is a dark star or GR BH, and the unknown territory that exists within the EH. So while that remains unknown, [although we are confident that it is the GR variety] we would still see the GR effects on space/time this side. [as we have plenty of evidence for that with planets stars etc]

Hope all that makes sense!

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Yep, that's certainly a valid statement.

 

OK Russ that was funny. Anyway the wiki says that Dark Stars have matter within the event horizon which is not a feature I remember reading about them. If we're just playing name games what about "frozen stars":

I'm taking Oppenheimer's stance here, but extending it. The outside observer claims that the black hole is a frozen star...but unless that black hole was ETERNAL (predating the Big Bang, etc) then its event horizon would be a point, for it would have been frozen at the time of its creation (from the outsider's perspective). From an outsider's perspective no mass ever crosses the event horizon, it only asymptotically approaches it...and since the event horizon begins as a point at the center of the collapsing mass, no mass ever actually crosses it at all because the entire universe is considered to be outside of it.

Again, we can call it a black hole, dark star, frozen star or Satan's Anus for all I care, and I will concede that if they all look the same to us as we observe them from this blue rock then it might be splitting hairs...but until I hear an argument to refute my logic I won't change my mind.

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On my point of view, something that exists is something we have proof of. And I am not sure we have proof of black holes. I'll search in encyclopedias and then I will send you a message.

 

The point is they exist......and no philosophical inuendo will change that.
I certainly do not see any logic in any philosophical stance, that infers all observational and experimental evidence and data is not real...
And as I have said before, the EH defines the fact that a BH exists.

 

Scientific models and theories such as BHs do not align with proof and neither does the scientific methodology.

Models and theories stand or fall on evidence and predictions supporting their existence.
To infer that BHs do not exist, defies all of the observational evidence supporting that concept.

ps: While you are searching for your "proof " of BHs, you would also be advised to look up the meaning of a "Scientific Theory "

 

This is, like most of the stuff you post, incorrect. It is the coordinate time to reach the EH that is infinite. This is simply an artifact of the mathematics used to describe the equations of motion, not a physical effect since the proper time to reach the EH is finite. You are definitely picking up your "pearls of wisdom" from pop science and this keeps biting you in the behind. For example, GR teaches you that the proper time for reaching the EH when starting at radial coordinate \(r_0\) is:

\(c \tau=\sqrt{\frac{r_0}{r_s}}[r_0 atan (\sqrt{\frac{r_s}{r_0-r_s}})-\sqrt{r_s(r_0-r_s})]\)

where \(r_s\) is the Schwarzschild radius. Obviously, \(\tau\) is finite.

By contrast, the formula for coordinate time has a term in \(ln(r-r_s)\) (aside from some other, more "civilized" terms) that obviously goes to infinity when \(r->r_s\).

All cranks say the same.

 

Yes, imagining the infalling frame is the standard response (as I've alluded to a few times already). Proves nothing. This is the equivalent of saying that New Years Eve 2013 exists for someone at that time therefore it exists for us today...it's exactly why I brought that up!

Why don't you post the proper distance to a point beyond the event horizon for us?

 

You are manipulating buzzwords . Again.

What did I just tell you?

 

There have been some complaints about this thread.
Disagreements are OK.
Being wrong is OK.
Discussing different ideas is OK.

Impoliteness, insults, ridicule, and other anti-discussion behaviour is not OK.
If you think they're wrong, say so, say why, and listen to the response. If you can't progress politely, then leave the discussion.
If someone engages in anti-discussion tactics against you, then ignore them. You can report posts, but moderator response is variable, so you won't always get fast resolution. Sorry.

 

The distance to the EV coordinate singularity is finite. I'd write it down for you but the last time you just ignored it. It's not necessary to use coordinate systems to explain this physics.. John Michell made his dark star proposal in the 1700's. He assumed that you could crowd that much non degenerate matter into a space defined by r=2M. In point of fact he didn't know what degenerate matter is or anything associated with the Pauli Exclusion Principle or the standard model of particle physics [quantum physics] since they didn't theoretically exist during his lifetime. Subsequently his proposal becomes an exercise in arithmetic at this point in the history of condensed matter physics. Subrahmanyan Chandrasekhar used QM to show there are no stable solutions for for M > 1.4 solar mass. Wolfgang Pauli explained how electron degeneracy and neutron degeneracy can result in stable gravitationally collapsed objects < 1.4 solar mass. Nothing bigger.

 

I'm aware you're playing games, but I'm not. We already agreed:
1. Cygnus X-1 exists.
2. Cygnus X-1 has all of the currently observable properties predicted by black hole theory and none that aren't.

Therefore, Cygnus X-1 is a black hole and black holes exist.

There is no point in trying to attach a different name to it or find another theory that may also apply - it wouldn't change any of the above or the conclusion. Again; it is just a game you are playing that means nothing. The wiki even says that the term "frozen star" is just a discarded name for a black hole. It is just an alternate name for an object that you are acknowledging exists. You're just playing games, trying to reject a name while simultaneously accepting that the object for which the name is applied exists! It's silly.

There are two logical complaints one might have regarding black holes:
1. Certain properties will never be observable. While true, this does not stop us from naming them any more than the fact that certain properties of the sun will never be observable.
2. Black hole theory may not be completely correct. This also may be true but again does not stop us from applying a label any more than it stopped us from applying the label "gravity" when Newton's theory of gravity was found to be wrong or not discarding the name "planet" when the theory on what they were was found to be wrong.

 

The word "proof" (proven) does not mean what many people think it means. It has two separate meanings:

1. Evidence. That's the definition that applies here. We have proof of black holes = we have evidence of black holes.
2. Shown to be true. A theory is proven when enough evidence exists that it is judged to be true.

Neither of these imply an absolute, though many people wrongly believe they do. Proven does not mean 100% proven, it means proven enough to become accepted. Similar to "proven beyond a reasonable doubt" in law.

 

I don't see the problem, honestly. A GR black hole is just a certain configuration of spacetime that contains a singularity. If you can cope with the idea that spacetime exists, then black holes shouldn't pose any additional difficulty as they're just a special case of that.

But simply making up definitions isn't exploring concepts.

It might also help if you were clear, especially with yourself, what you were really concerned with. Some of your comments seem more concerned with epistemology (knowledge and the question of how we form beliefs about what exists) rather than what existence means in itself, for instance.

I've already said I don't think it's definable. It's a simple logical fact that not every word or concept can be given a definition, and existence just seems to be one of those base concepts we have that we can't define because there isn't really anything we could define it in terms of.

By [POST=3125648]your definition[/POST]? Yes, I'd have to disagree, because parts of a black hole can be spacelike separated from an outside observer.