What dimension does a black hole exist in?

[Kyle]

Looking for thoughts on this. I've talked for a while about whether black holes are actually four dimensional objects that exist in proximity to- but not in- our three dimensional world of space time. But as I was driving in this morning, I began to question this. If everything is sucked inescapably into a black hole by the tremendous gravity, isn't it actually just a one-dimensional object? Maybe not, because I know that black holes emit tremendous amounts of energy at times, and those radiate out in our three dimensional reality. But is it possible that instead of black holes existing in higher dimensions, is it the case that they live in lower ones?

Having postulated this, I know leave it on the boards to be ignored except by the one person (usually Mike) who posts up a response of "Dude. Have you ever thought about... like... the universe is just huge, dude..." and other stoner talk.

[Tahlvin]

Whatever dimension(s) it wants to exist in! Bah-dum-bum!

[Kyle]

[Phoebe]

[Kyle]

[Tahlvin]

It's a singularity, so it exists in only one dimension, but affects all dimensions. So it's non-dimensional.

[Phoebe]

I don't know what that means. Not sure what we are talking about here. I guess we are not talking about an event horizon. Are we just talking about what the singularity in a black hole is? I don't claim to understand all of this but I do get my info on it from a reliable source and I'm happy to relay questions.

[Bonefish]

I think Tahlvin is right. Or on the right track.

A black hole exists across every dimension. Just like we exist across every dimension. But a black hole is just a single point on at least three dimensions. Which apparently nature abhors, because you'll never find a naked singularity. They will always be hidden behind an event horizon. I think.

[Phoebe]

I thought some dude had argued it is possible to have a naked singularity, but I don't know if he was right. I thought the only thing that prevented some black holes from being spherical is rotation, but even then it's more of an intersection of spherical shapes, yes?

What do people mean by calling a black hole a point or one-dimensional, non-dimensional, cross-dimensional, etc? I think it's that when you get a large enough mass compressed into a small enough space, you need quantum theory to explain what is going on in that space. There are different units of measurement to account for such spaces. I don't understand what they mean, apart from the fact that they describe places where general relativity stops accounting for things as it otherwise would.

[Mike]

All matter is also technically energy. Therefore, no particle can be compressed into an area smaller than it's wavelength. Particles of the same type can theoretically be forced to occupy the same quantum state simultaneously. Therefore, all the various particles that fall into the black hole will be sorted into specific quantum states by wavelength... all of them superimposed on each other. Presumably then, the matter that makes up the black hole will have a (spherical?... I don't know) three-dimensional volume with a diameter equal to the longest wavelength of any particle therein.

Maybe?

Alternately, you can simply measure it's volume by its event horizon, which is a huge and easily defined spheroid in three dimensional space.

This is all guesswork.

[Bonefish]

Phoebe: It's a point. Think back to geometry, where you could have a dot on a paper be a point, like say point A. If you have another point, like point B, you can draw a line from A to B, and it has two dimensions(because you have two axes of measurement, width and length. If you add a third dimension you get height, but you can't really represent that on a two dimensional surface. But if you did, you would still have a black hole being a single point, a single dot.

Mike: the matter/energy in a black hole does escape the event horizon. Even though they should in theory only have 1 dimension, Heisenberg's Uncertianity theory means that it's impossible for them to all occupy the same space at the same time(because you can only fix a particle to either a velocity or location, but never both at once). It might be Heisenberg, or it might also have to do with Schrodinger. This means that particles near the edge, but in the event horizon, can "evaporate" back into realspace due uncertainty.

It's slow and small, but it should happen, and an old enough black hole would have lost considerable amounts of it's mass, decreasing it's event horizon's size. Eventually, such a black hole would get to the point that it's mass is no longer sufficient to capture light, and well... I guess it explodes with a lot of force.

[Mike]

It's Heisenberg. If black holes did not radiate, then the the event horizon would have precisely known position and energy. Heisenberg's principle says that's impossible so it necessarily radiates. Black holes without fuel for further growth would eventually radiate all their mass away as energy.

[Phoebe]

I don't think a black hole is a point like a point in coordinate space. Again, I don't know much about this, but I have a good source, and from the little I do know, there are singularities of time and singularities of space. When I think "black hole" I am thinking of whatever is beyond the event horizon, and there is a radius which corresponds to some relation involving the amount of mass condensed to create a black hole. I know that some black holes are said to have a rotation or spin, and maybe this affects the nature of the event horizon. I think the event horizon is a point beyond which the usual physics rules of general relativity no longer offer a meaningful description of what is going on, and we need a different account of gravity or of whatever is happening. Presumably quantum mechanics offers us such an account, and right at this point I hit a hard limit of my knowledge because I don't even begin to know why or how that works. I don't know what it means exactly for a black hole to have a radius, or for its event horizon to be spherical (or that perhaps spin creates something else), because I can't do that math and I feel like we get to a point here quickly that, absent a grasp of math, we don't even know what we are talking about or what physicists are debating here. I'm about where I was at age 19 on this stuff, no further.

[Mike]

Thinking of a black hole as being defined by its event horizon can be useful, but it's not an actual physical object. The event horizon is the point of no return from which light can't escape, but most things are slower than light, and their individual points of no return are much farther out. If you were in a spacecraft flying ever closer to a black hole, you would not be able to spot the event horizon. Even as you crossed that limit and continued closer, you would never notice anything different about that area of space. The event horizon is a calculated thing.

The actual mass of the black hole resides at the center of that, and is the densest material in the universe. In fact, if I understand it correctly, the matter of a black hole is compacted into a space that is as close to zero dimensional as we can get within the margin of error of existence.

[Phoebe]

That's how I understand it too, except that I don't know what it means to talk about dimensionality in that context, given that the standard rules of physics aren't accounting for it, and I don't think there's an accepted view on the matter. I'm stuck at about age 19 on physics though, for real, it's a struggle to keep current.

[Bonefish]

[bralbovsky]

So if it doesn't have an actual coordinate, whether that's in motion or not, is it energy instead of matter? I'm likely decades behind the thinking on this, but if it has "mass" or what passes for mass......
Further, if Australian scientist A can find it, and call Brazilian Scientist B, who calls Chinese scientist C, and they all agree where to look...

It must therefore have a locality, which I agree you wouldn't notice from close up, like a waterfall you might be captured by before you can hear it.

I'm far enough behind to feel that something built of captured and crushed quarks and photons and other atoms, despite their compression, has to have at least theoretical dimension, asymptotically approaching nil, but dimension nonetheless. Help me out here.

[Mike]

My understanding:

Matter and energy are the same thing at the extremes of the universe.

The various astronomers can look that way, but they don't actually see it. They measure its side effects and its effect on the things around it, and that tells them where it is.

From the outside, nothing within the event horizon of a black hole can be seen. But the spheroid defined by the event horizon is enormous, and the mass of the black hole is (theoretically) compressed into a microscopic spot at the center of that.

Saying we can't know position and velocity simultaneously only means we can't know both exactly down to umpteen decimal places. We can find position and velocity of most things pretty easily, but our level of preciseness is limited.

If that makes sense.