Have black holes been PROVEN to exist...?

Question

I know that most physicists and cosmologists accept that they probably do exist and work on that basis, but do we know for a FACT that they are there. For example, have we actually seen one?

Or are they still fundamentally theoretical in the same way that Big Bang and Relativity are?

Please only answer if you know for sure. This is to settle an argument, and a dinner for two at Berni Inn rests on it.

Thank you :-)

Shooting-star - you are starting to bore me. Please go away - Crispy and I are just laughing at you, is that what you want?

OK - I took this off a physics website, which appears to say that they are theoretical:

A black hole is a theoretical entity predicted by the equations of general relativity. A black hole is formed when a star of sufficient mass undergoes gravitational collapse, with most or all of its mass compressed into a sufficiently small area of space, causing infinite spacetime curvature at that point (a "singularity"). Such a massive spacetime curvature allows nothing, not even light, to escape from the "event horizon," or border.

Black holes have never been directly observed, though predictions of their effects have matched observations. There exist a handful of alternate theories, such as Magnetospheric Eternally Collapsing Objects (MECOs), to explain these observations, most of which avoid the spacetime singularity at the center of the black hole, but the vast majority of physicists believe that the black hole explanation is the most likely physical representation of what is taking place.

Can someone explain? Pleeeeeeeeeeease! I don't want to have to buy Crispy dinner - I'll be in debt for the ret of my life :-(

With regard to big bang and relativity - in science it is very hard to prove something as fact. This is because you can do an experiment a million times, but you cannot be certain that you will not get a different result the next time you do it. Therefore, while something can look HIGHLY probable and fit all the known facts, it must still remain theory. Sounds daft, but that is simply the way it is. Eri is the only person who seems to have actually answered the question and has grasped that fact.

I think the question is pretty clear - and I haven't said that relativity is "purely theoretical", just that for the reason I gave above it can only ever remain theory. I do not doubt - no do any of us really - that black holes exist. But I have been trying to tell my friend that, like most things, they are still theoretical. I think I'm right, actually.

Answer 1

Proven? No. Basically, a black hole can't be seen directly - but we're familiar enough with what *effects* they *should* have to determine if they exist.

So, we see the effects of objects close to black holes, and based on those effects, we can say that they support the theory of the black hole. But it's *possible* that there may be another explanation for what we're seeing. While most scientists are 99.99% sure black holes do exist, and that there could be *no* other explanation, we can't truly say they're more than a theory.

Answer 2

Like others that have stated,
Nothing is proven 100%. All the data shows there are massive compact objects out there which seems to show all the evidence that there is a black hole out there. We know for a fact that something is out there. All the indirect evidence shows that the properties match what black holes should be doing. Thus it is most likely a black hole out there in space.

This is the same for Relativity and Big Bang models. How do you know they work and are the best models of the universe? Those models predict certain things predict certain other things cannot occur. So you test. Ahah! Look there are the things predicted and we don't observe the other stuff that would dispute the theory/model. Hence, the model if very good. If the predictions don't work out then the model is revises and checked again.

What we have seen are all the indirect evidence of a black hole since direct light from a black hole cannot be observed (pretty much). What are indicators of black holes? Accretion radiation, jets of energy from the poles, x-rays, masses greater than 3 solar masses... etc. We look into the sky and we see some accreting material. Hrmm.. maybe its a black hole. How massive is the object? Oohh over 3 solar masses. A better candidate. So the scientists continue on going through the check list. Finally with all other sources ruled out the object could only be a Black Hole or some exotic thing no one has theorized about. Wtih great confidence, lets say up to 3 or 6 sigma (> 96%), we have a black hole candidate!
So it is very reasonable to say that we have black holes in space.

It's like solving a murder case. Let's say no one saw the murder happen. How do you know the defendant killed the victim? You weren't there. You did not detect the light that was from the murder and hence you did not witness the act. However, there are other pieces of evidence. Look for DNA, look for motives, fingerprints, alibis, time, location, etc. All these parameters go in to the case. Once all the evidence is in, can you say with that without a reasonable doubt that the defendant killed the victim? Looking for a black hole and proving a black hole is similar (simplified of course). You never see the black hole like you never saw the murder. However the accretion radiation, the jets of energy at the poles, the mass of the object, are all pieces of evidence of the black hole just like dna and fingerprints are evidence that the defendant committed the murder. Gathering all the evidence, the scientist can say with good percentage that what is out there is what scientists call a black hole.

Hope that helps.

Answer 3

No we do not know for a fact that black holes do or don't exist. To prove such a thing or anything out of reach in the vastness of the universe will not be proven for a very long time, if at all.
But we do have some excellent theory's to work with, and using these theory's with other information we can build up an idea what should be there. A theory can be a well-tested truth in which all scientists have great confidence. Yet we can never prove that any theory is absolutely true.

Answer 4

well first of all im gonna straighten something out, relativity is not theoretical anymore. we've proved time dilation, which is a direct by product of relativity. other experiments have also proved Einstein.

and we havent been able to DIRECTLY observe black holes, and we never will be able to. but we have seen their gravitational effects on things around them. and within the last probably decade or so we have found that we can see a massive amount of radiation from particles on the event horizons on black holes.

so yes, black holes are proven to exist, well at least something like them. recently, some physicist has claimed to have proved that black holes violate the theory of relativity, so he has come up with another object, almost exactly like a black hole, but very slightly different.

Answer 5

You use the term "fundamentally theoretical" in reference to the Big Bang and Relativity. I'm not sure exactly what you mean by this is that they cannot be proven as fact. The reality is that no physical theory can ever be proven beyond a shadow of doubt.

The best we can do is show that a theory supports our current observations and in fact that's how theories are developed. But this isn't to say that newer observations will never falsify our most venerated theories. As our measuremens become more and more fine tuned we may arrive at deeper meanings behind them forcing us to revise our existing theories. That's how the quantum and relativity theories came into existence.

What does this have to do with black holes? As the others have said, we can't see them directly. But we can see their effects on nearby objects, such as rotating disks or jets of gas heated to give off x-rays. And what we refer to as black holes are objects that cause effects that match the theoretical predictions for black holes and cannot be caused by any other object known. In addition the theories these objects are based on have been tested experimentally to extremely fine leves of detail.

Is this good enough for you? I have no idea because what you are asking seems quite vague. For example, I would not lump relativity into "purely theoretical" since your car's GPS (if you have one) relies on relativity being true. If it wasn't your GPS system would be off by many miles. The existence of black holes relies on the same theory as your GPS. If you rely on your GPS you should rely on the existence of black holes. ;)

Answer 6

A philosophical thought first:

Can you PROVE to me that you exist?

Of course not. Life is not the same as mathematics.
What you are is not determined by a set of axioms and a choice of logic that I get to use for my existence proof on paper. Because "mathematical proof" is the one and only definition of "proof" that exists in science.

But because life does not work anything like mathematics, scientists need to agree on other criteria for what we call "reality". And within those criteria, the answer to your question is: "Yes, black holes exist and we have 'seen' plenty of them".

So why do I assume that you exist and how does that translate to black holes?

How do I determine that you/they exist?

Well, I make some observations!

In your case, I immediately notice that you behave like a human being. You have thoughts, you have questions, you are capable of human speech and... everything I know about you is CONSISTENT with the hypothesis that you are a human being.

In your case, of course, it is easy because we have yet to genetically engineer talking farm animals, rhyming cabbage or build software that exceeds the mental capacity of a three week old earthworm.

And because I can rule out that you are neither a talking farm animal, a rhyming cabbage or software, I can, even without having "seen" you, at all, assume that you are indeed, human. Human is the one and only possibility I KNOW OF that fits.

It is very much the same with black holes. We have plenty of observations of very small objects which send out enormous amounts of gamma and x-rays. We can see that the signatures of these radiation bursts are compatible with an object that has to be smaller and more dense than a neutron star. We know from nuclear physics that nothing smaller much than a neutron star can exist which is so close to the size and "density" of a black hole. So if it is not a talking farm animal, if it is not a rhyming cabbage... it has to be a black hole.

As for the idea that black holes can't be "seen", that is total nonsense. They can not be "resolved" with optical astronomy, that is true. But there are plenty of proposals for experiments that attempt to image the event horizon of a black hole and the radiation field of the in-falling matter that is outside.

See e.g.

http://constellation.gsfc.nasa.gov/index.html

As far as your assumptions that relativity and the big bang are "theoretical", I have to disappoint you. If you ever had a color television set in your life, you were using a device that had relativistic electrons in it. If you ever had an x-ray in your life, you were bombarded with radiation which would have been impossible without relativity. If you are using a GPS to find your way... you are relying on equations from general relativity without which the device would be off by quite a bit. And radio waves and light... well, they are both inherently relativistic because Maxwell's equation can not be made consistent in a world of Galileo transformations.

And yes, I know for sure.

:-)

Answer 7

You can't SEE a black hole. A black hole, as I am sure you are aware has such powerful gravity that light itself cannot escape.

However, they do emit radio and other waves that we can detect. We can see the effects of black holes on neighboring object's orbits. So we know them to exist, since we can see the evidence of them.

However, it is much harder to prove something than it is to disprove it. The Theory of Evolution remains a theory, since we are not able to track the change of most creatures beyond a few generations, and evolution takes a LONG time, and we humans have been here for a very short time.

Answer 8

You can't see a black hole because no light or electromagnetic radiation (of which visible light is only a small portion) or any other kind of energy or any matter is emitted by a black hole. You can only see how it affects the objects and energy within a certain proximity of it. Scientists know that SOMETHING is pulling in all of that matter and energy. They choose to call that SOMETHING a Black Hole.

That Black Holes EXIST is not theoretical. Exactly what Black Holes ARE is theoretical.
.

Answer 9

While scientists are extremely confident that black holes do exist, absolute proof is impossible. This is a basic tenet of science - you can never be 100% certain about anything, but you can be extremely confident. The observational evidence in favor of black holes is very strong, but we have not directly imaged one because their event horizons are too small and too distant to be resolved with current instruments. Scientists can infer their presence by examining their effects on nearby objects, but there is a very small chance that black holes don't exist and that scientists are actually detecting some unknown phenomenon. I must stress, though, that there's so much evidence in favor of black holes that it would be nothing short of shocking if they don't exist.

Answer 10

Nothing is ever proven without a doubt in science, but black holes, the big bang, and relativity are very well established. We can't see black holes because of their intrinsic nature, but we can establish that they exist by looking at the superheated material falling into them (and emitting x-rays) as well as the local gravitational effects (huge with no visible star).

The big bang theory is well-backed-up with the results from COBE and WMAP, not to mention Hubble's observations of the expanding universe. And Gravity Probe A established the truth of relativity.