Black Holes NOT Science?

AdkinsJr

I read an interesting article which asserts that the existence of black holes cannot be falsified, and therefore they do not qualify as science. Has anybody heard this argument before? Any comments?

russ_watters

No one answered the question, though....

Black holes are objects and they most certainly exist as they have been observed countless times. In addition to the factual existence of the object, there is also a theory (many theories) about what, exactly, they are. These theories are pretty good but not yet complete (and may well never be). One particular aspect - what, exactly goes on behind the event horizon may be unfalsifiable due to its unobservability.

jobyts

Is there an equation that calculate how much gravitational force is needed to bend the light, say, to form an arc of x radius?

EDIT: Never mind. Some google search pointed me to the following url.
http://www.mathpages.com/rr/s6-03/6-03.htm

I don't think I'm knowledgeable enough to understand these complex equations. It's more than my brain can handle. Wish they were simpler.

matt.o

I think you state this too strongly. We have much observational evidence for the existence of black holes, such as jets and accretion disks associated with supermassive black holes and other high energy phenomena, or the orbital motions of stars close to Sagittarius A. However, the defining feature, an event horizon, has never been observed.

twofish-quant

But curiously enough you can observe something that would cause a "major problem." If you have something with a hard surface like a neutron star then stuff that falls on it will accumulate and if it is hydrogen eventually you get enough to cause a flare. With a black hole, there is no hard surface so stuff keeps falling in. The other thing is that to get a pulsar you have to have something getting emitted from the surface.

So if you have a very massive compact object which emits flares or is a pulsar, then you have some explaining to do. It so happens that we don't observe anything like that, and all of the accretion disks that do flare up and pulsars are objects which are below the black hole cutoff line.

Since you have observations that would falsify the existence of black holes (i.e. if you say an eight solar mass pulsar), it's science.

russ_watters

I'm not sure I'd call the event horizon "the defining feature", but semantics aside, I don't see why that would matter anyway. By analysis of gravity alone, you can identify a region of space where a massive object must reside. That object emits no light. Therefore, that object is a black hole. Not being able to visualize the boundary of that object doesn't change the fact that we know for certain we are observing (via its gravitational pull) a massive object that doesn't emit light.

matt.o

Well, observationally speaking, since the event horizon is the "last frontier" beyond which nothing more can be observed, I would say then that it would be the best that can be done as far as providing ultimate proof of the existence of a black hole.

By your line of reasoning, Dark Matter can also be classified as a black hole since it too is massive and neither emits nor absorbs light. All we can say currently is that there exists a massive, dense object. I believe that recent Very Long Baseline interferometric observations have come close to detecting an even horizon, but that's as close as we've come.

trini

for the gravitational field at a point to be strong enough to justify itself as a black hole, there must be an extremely dense point of charge. because light itself is a wave function, one can probably imagine that a body of charge which is compacted to extremely dense states will not be able to vibrate internally. remember that in infinitely high gravitational fields, "time" slows to zero, which is to say, there is no motion of charged bodies relative to each other. because an em wave is caused by a perturbation in a static electric field, when there are no vibrations, there is no light.

I believe that energy, on the whole, behaves in such a way that it likes to be in motion. this is why we can't achieve 0 K to date, energy just doesn't like remaining still[perhaps due to the fact that we ourselves on earth are part of systems which change position relative to others, ie, our planet orbits in the soalr system, which in turn orbits the galactic bar, so on some tiny level, there is always likely to be some "universal shake" occurring due to our primary source of rotation]

Because energy must be very dense in a black hole, it becomes very hard to move. Since it wants to move, the black hole effect of sucking in whatever is around it may be the core energy bombarding itself with as much energy as possible to try and achieve vibration.

the event horizon itself may be a ball of vibration-less energy, that is to say, when things are sucked onto the event horizon, super huge gravity instantaneously stops any potential vibrations caused by the collision of absorbed matter with the core, including the vibrations in the absorbed particle itself, so the particle then becomes part of the event horizon, it goes "black".

black holes exist however, whether or not our understanding of them is correct, even if it turns out they weren't holes, the concept of the black hole is that of a region of high gravitational potential(ie bends light), coupled with no observable vibrations coming from within.

russ_watters

But your complaint above was that the event horizon is not observable, wasn't it? Is the event horizon observable even in theory? If the event horizon is not observable, why should it be a problem that we can't observe it?

Anyway, this still doesn't trouble me at all. If you close your eyes and walk around your room, you might bump into something that feels like a chair. Is it a chair or do you have to see it with your eyes to know for sure? Is dark matter of a similar density to black holes?

matt.o

You should re-read my post.

Well, if all scientists settled on logic like this, there would be nothing more to do, right?

No, it is not, but your criteria was that to be defined as a black hole, an object just has to be massive and not emit light:

russ_watters

Uh, ok.... You said: ......so what is your point? Huh? Nothing I have said suggests that science has nothing more to do. There is a lot of work to be done on black hole theory. Is dark matter "an object"? In any case, perhaps I was slightly too simplistic. So what? I think you get the point - I have no idea why you are being so argumentative.

matt.o

I'm trying to show you that statements like:

Are simply not true.

Chronos

I'm pretty convinced of the existence of black holes, but, have not heard any claim of proof to date. We know there are some suspiciously dense objects in the universe, and can at least infer they are probably black holes. That invisible spot in sagittarius with stars zipping around it at ridiculous velocities looks fairly compelling. An interesting point, however, is it appears extremely massive stars blow off too much mass to allow formation of stellar mass black holes. Neutron stars with masses in excess of about 1.33 solar mass are virtually unobserved to date - far short of the ~ 3 solar masses necessary to form a black hole. The smallest black hole detected to date weighs in at nearly 4 solar masses [http://www.space.com/scienceastronom...lackhole.html]. This is quite a mystery, imo. Where are all the 'tweeners'?

russ_watters

Why didn't you say that before? Before you just said "too strong". I don't find it useful to be argumentative like that: if something is wrong, say it is wrong and explain why.

So far your quibbles have just been with the particulars of my admittedly simplistic definition. But I don't see those quibbles as being substantive/useful. Ie, no cosmologist would say an identified black hole is also consistent with dark matter, would they? Would a cosmologist identify this photo as a photo showing the aftermath of the creation of dark matter? http://chandra.harvard.edu/press/08_...ss_041608.html

The wording of the article seems pretty unequivocable to me. They aren't saying that SGR A 'appears to be' or 'is theorized to be' a black hole. It is a black hole.

WhoWee

Chronos, (as you've pointed out) "A fish cannot comprehend the existence of water. He is too deeply immersed in it."

chroot

Russ,

I think your conviction is understandable, but also too strong.

As Chronos said, we have observed curious things in the universe -- immense sources of energy, jets, accretion discs, large gravitational effects on other objects, even gravitational lensing -- which can only be understood as the consequences of extremely massive (and dense) objects.

Currently, the only theoretical candidate that we have to explain these observations is the black hole, as described by the general theory of relativity.

If you take the definition of "black hole" as "super dense body," then yes, there is observational proof that black holes exist. If you take the definition of "black hole" to mean the narrower "body as described by general relativity," then their existence is, at best, plausible. The actual nature of these super dense bodies could be radically different than anything we think we know today.

- Warren

matt.o

Actually, I think I did explain why I thought that statement was too strong. I'll admit that perhaps I was too strong in saying your statement was not true, and would have been better to say it was misleading.

My quibbles are with your penchant for dogmatically stating things. This is unscientific and does not help someone's understanding.

Ugh. This is a press release, and I also have problems with the way things are stated "as fact" in these things. Read the wording in the following journal articles: Detection of the Intrinsic Size of Sagittarius A* Through Closure Amplitude Imaging, The Event Horizon of Sagittarius A* or Title: Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre and note the use of phrases like "black hole candidate".