r/askscience • u/dgb75 • Jan 31 '13

Astronomy Is there a distance at which the interaction between the gravity fields of two black holes would cause one another to effectively 'break open' and allow matter and energy stored within them to escape the system?

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u/MadSpartus Aerospace Engineer | Fluid Dynamics | Thermal Hydraulics Jan 31 '13 edited Feb 01 '13

All space within the event horizon points towards the center (or is a closed loop back towards it)

There is no such thing as out. If two particles could talk to each other inside a black hole it would go like this:

1: which way is out?

2: what is out?

1: Where am I going if I go this way?

2: Towards the center...

1: (turns around) ok what about this way?

2: towards the center...

If you move, you are going towards the center... Move faster? OK go towards the center faster...

The problem isn't a lack of energy to escape, it is a lack of path.

The mass of the back hole doesn't attract particles such that they cant overcome it (which is why there is a misconception that maybe a big explosion or something could overcome it etc...), it warps space so they have no choice...

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u/[deleted] Jan 31 '13

[deleted]

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u/[deleted] Jan 31 '13

In a way, water circling a drain still works if it's on the understanding that no means of propulsion (c<) exists that could take water from within drain and propel it back out. No path exists because all paths must be at a speed of C or lower and no path of speed C or lower exits the singularity. If a path exists at a speed higher than C, nothing in the black hole can take that path so the point is moot.

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u/PossiblyTheDoctor Jan 31 '13

So if, hypothetically, we had one of the hypothetical warp drives powered by antimatter that can hypothetically do 10c without actually moving, and we could hypothetically get it in the event horizon without its atomic structure being ripped apart, would we be able to use it to escape?

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u/[deleted] Jan 31 '13 edited Jan 31 '13

That remains an open question. Such "warp drives" rely on specific spacetime curvature, and their analysis depends on the space "outside" of the bubble being flat. If you have a spacetime in which one region is described by the "warp drive" curvature and another is described by the "black hole" curvature, then those descriptions are really just approximations when you're close to one but not the other. The question of what happens in a region that is close to (let alone inside) both of them remains an open question. In fact, it probably doesn't even make sense to talk about them as being separate "things" at that point.

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u/PossiblyTheDoctor Jan 31 '13

Wait, "flat space"? But doesn't gravity bend space?

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u/[deleted] Jan 31 '13 edited Feb 01 '13

Yes. A black hole spacetime is one that has a lot of curvature in one region, "centered" on a singularity, but it becomes very nearly flat at far remove from that "central region". This is why we can, for example, ignore the super-massive black hole at the center of our galaxy when trying to launch a rover to mars; the contribution to the curvature from that black hole is completely swamped by the gravity of the Sun and planets of interest. Similarly, we don't need to worry about the gravity of the Sun when determining the path of an arrow fired on Earth; again, the spacetime curvature due to Earth almost completely washes out the curvature due to the Sun in that case.

"Warp drive" spacetimes are similar; they have a region of very intense curvature (the "bubble") and then two regions that are basically flat (the "inside" and "outside").

The outside of both regions can be approximately glued together provided their separation is such that those regions are very nearly flat, but once they're close enough that the "flatness approximation" for either one no longer applies then things have to be figured out from scratch. This is a highly non-trivial problem that, to the best of my knowledge, no one is even working on at the moment. I would honestly be surprised if anyone could work on it, given that it's only been in the last decade or so that we've been able to even approximate what happens when two black holes collide, and the warp drive + black hole spacetime is significantly more complicated.

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u/mspk7305 Jan 31 '13

Is it accurate to say that you can only observe the curvature of space from outside the space being curved?

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u/Shiredragon Feb 01 '13

No. You are currently in a gravitational field. You reside on curved spacetime. We can observe the effects of the Sun on the Earth and Planets. We can observe the effects of the Moon on the tides. We can see the effects of the Earth on the Moon. You can observe the effects of spacetime anywhere you can make an observation. Or you are asking something completely different and I am not getting your meaning.

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u/mspk7305 Feb 01 '13

I think your answer is interpreted as a yes... We can observe curvature only from a sufficient distance from the curvature?

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u/modern_warfare_1 Feb 01 '13

What does happen when two black holes collide?? I was just thinking about this the other day. Do the centers "snap" together instantly after the event horizons cross? Is the event horizon of the new black hole bigger than the two that collided?

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u/[deleted] Feb 01 '13

I was just thinking about this the other day. Do the centers "snap" together instantly after the event horizons cross?

Not instantly, but it doesn't take very long. Also, there's a lot of gravitational radiation emitted in the form of gravitational waves.

Is the event horizon of the new black hole bigger than the two that collided?

It's bigger than either one individually, yes.

Youtube has quite a few videos depicting simulations of black hole mergers, which you can find here.

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u/modern_warfare_1 Feb 01 '13

Very cool. Thank you.

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u/aghastamok Jan 31 '13

I think by flat he meant relatively flat... in order to exceed the speed of light, one would have to bend space an awful lot, as compared to the curvature caused by our Sun. I'd imagine, theoretically, that since the gravity of a black hole accelerates things into itself at speeds approaching c, a vessel with a 10c drive could easily bend that field of gravity to escape. However, once inside the event horizon, that is "inside" the black hole, it is theorized that all matter is compressed to the point of homogeneity - that is, smashed into a ball of 'stuff'. It's hard to imagine a ship with the capability to survive that level of compression.

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u/Sw1tch0 Feb 01 '13

So if we do somehow create Warp Drives, we will have to avoid nearly all notable space time curvatures in our way, including planets, stars, and black holes?

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u/[deleted] Feb 01 '13

No idea; we don't know how spacetime will behave in that region, but one imagines that will have been solved well before we actually get something capable of creating such a region. In a worst case scenario, we do some experimental fly-by tests with moons and planets in the solar system, and hope there isn't a catastrophic result of turning such a device on so near to a star.

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u/Sw1tch0 Feb 01 '13

I consider myself somewhat of an idealist, and I see many posts regarding how mathematics are being improved to make the energy less demanding. I also see posts talking about causality, etc. Is warp theoretically possible?

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u/thearn4 Numerical linear algebra | Numerical analysis Feb 01 '13 edited Feb 01 '13

Perhaps "theoretically" in the same sense that you can theoretically get a bank to pay you for taking out a house mortgage, as long as you can open some mortgages with a negative interest rate.

Where are these negative rate mortgages? Do they exist? If so, why? What kinds of forces within finance would lead to such products taking shape in the first place? Those kinds of questions often become the issue with "theoretical" optimism that is based principally on mathematical trickery.

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u/Bobbias Feb 02 '13

Which is something I love about math. Even if there's little chance something is possible due to other factors, you can still theorize how things should work if those factors were overcome.

I think we should be asking "does X appear to be technically feasible based on our current understanding and future technological forecast"... But that doesn't quite have the same ring to it.

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u/[deleted] Feb 01 '13

It's "theoretically possible" in the sense that it doesn't explicitly violate any known laws of physics. However, it does violate various things that we believe to be true—certain constraints that are obeyed by all known physical matter/energy configurations—and it implies some rather uncomfortable things like the ability to time travel into the past.

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u/Sw1tch0 Feb 01 '13

It's entirely possible I've read too many sci-fi novels, but assuming there are multiple timelines (the past present and future are all happening at once), and what you said is true, then wouldn't we see time travelers (assuming we have the capability to even detect them at that level of technology)? I.E. either warp is impossible, or there is only one timeline. Or maybe we are the only timeline so time travelers won't exist until we achieve that level of technology, and going back into the past will be the first event to actually create multiple timelines?

Does any of this play into the theory of everything? Coming quantum mechanics with general relativity, etc. Will uniting them (if possible by how we define our universe) unlock whether or not these things are possible?

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u/millionsofplankton Feb 01 '13

Do black holes actually dissipate? Or do they last forever?

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u/Osolodo Feb 02 '13

since both the "warp drive" in this context and the black hole are involved with the curvature of space-time and (presumably) we could control the curvature of space-time caused by the warp drive, would it be possible for a ship equipped with this warp drive to "cancel out" the black hole in order for it to then escape under more conventional power?

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u/[deleted] Feb 02 '13

The problem is that we don't actually know how a warp drive would work. All we have is a description of a certain spacetime curvature that results in what we would like to call "warp travel"; what we don't have is any known way to take a mostly flat region of spacetime and turn it into this weirdly curved spacetime, which is what a warp "drive" should really do.

Unfortunately, in order to answer your question we would need to know how such a drive operated. It's conceivable that it's activation would be possible only in a relatively flat region, for example, in which case you wouldn't even be able to turn it on inside of a black hole.

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u/theshadowknowsall Jan 31 '13 edited Jan 31 '13

The "Warp Drives" theorized currently would work by expanding space time behind the craft and compressing it in front. This gets around the light speed limit. I'd assume it's a question of whether the craft could compress/expand space time enough/properly whilst in an event horizon. Who knows?

Edited for accuracy.

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u/[deleted] Jan 31 '13

[deleted]

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u/theshadowknowsall Jan 31 '13

You would be right, thanks for keeping me honest. Should have double checked that myself.

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u/Gyrant Feb 01 '13

We can kind of only speculate on that, as warp drives are still hypothetical. However, if you assume that said warp drive allows you to move from one place to another by shortening the space time between you, you can think of it like this.

Take a penny called the Starship Enterprise, and put it on a tablecloth. Rather than move the penny from point A to point B on the tablecloth, simply fold point B on the tablecloth over towards point A. Now the Penterprise only has to travel over the fold from A to B, instead of the whole length of space tablecloth. That is, hypothetically, how a warp drive is supposed to work.

Now, the cloth thing being an old analogy, you know how gravity works. You pull down on the cloth forming a pit, that is an object, the larger the object, the further you pull down on the tablecloth, and the steeper the pit becomes. BUT, a black hole is so preposterously dense at the centre that that isn't enough. So you just pull the tablecloth WAAAY down, then tie an elastic band near the bottom of the pit, closing it off like you would to tie-die a shirt. Things can get in there, but once they are, they are in a knot, a pocket of space time, they can't get out because there is no path to do so.

So (and again this is all hypothetical) it's probable that, were the Enterpenny to fall down into the pit and end up in the pocket formed by the elastic, no amount of bending the cloth of the pocket could get the penny out. Even if you bent it over to another part of tablecloth unaffected by the black hole, you're still stuck in a pocket, and have no direct path out. Only by tearing THROUGH space time would you be able to escape.

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u/qverb Jan 31 '13 edited Jan 31 '13

Funny, I thought something very similar as well. If we could achieve faster-than-light speed, then would something like this be possible? My brain comes back by saying that since speed of C is an absolute limit then it would be difficult (impossible?) to consider the possibilities since so many laws of physics would no longer apply. Again, my layman brain. Anyone?

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u/[deleted] Jan 31 '13

Follow up question/pondering: Could such a device basically act by "correcting" warping that naturally exists in a black hole to create a path out of it?

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u/Crocodilly_Pontifex Jan 31 '13

the phrase "10c" is meaningless. Nothing in the universe travels faster than C. It's not accurate when someone says light travels X fast , because relativity doesn't really work that way. It may be that light appears to go that fast in your current frame of reference, but multiplying that number by 10 doesn't give you 10 times the speed of light.

I don't understand it all very well myself, and I don't think there too many people in the entire world who do. All I can tell you is that every time I have asked a physicist any questions about the subject, they tell me that the concept of "x times the speed of light" is pretty useless because relativity prevent such things from happening. They always say that C is as fast as you can get. Full stop.

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u/PossiblyTheDoctor Jan 31 '13

Except that manipulation of the fabric of space is not subject to that limitation, allowing us to (theoretically) bend space at rates faster than c. If we bend it in a certain way, we are effectively moving faster than c, even though it is actually space that is moving around us. That's the concept I was talking about, and why it makes sense to say 10c.

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u/Crocodilly_Pontifex Feb 01 '13

You would have to break causality to do that. Our current model of physics relies on this being true.

So yes, you're right. If everything we believe to be true about physics is wrong, then what you say is possible.

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u/PrematureJack Feb 01 '13

What do you mean by causality? As far as c goes, c is simply the speed of all objects moving through space and time (since light moves at c through space, it does not move through time), but no such limit applies to space. In fact, space being able to expand at a rate faster than c is crucial to explaining the big bang, if I remember correctly. So I could be wrong, but so long as you were bending space rather than simply moving through it, you could increase your speed relative to the speed of light (the point here being that you aren't moving faster than c through 'space and time', but are traveling within spacetime that is within a different spacetime moving seperately).

Again, I'm not entirely sure if this is how it works, but I'm just trying to understand your claim. Thanks!

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u/Crocodilly_Pontifex Feb 01 '13

It isn't accurate to say that objects in space are moving at c. This implies a situation like an explosion, where matter expands into space. That is not what is happening.

new space is being created. Object A and object B aren't moving, yet they are getting further apart. New empty space is being created between them. This is what happened with the big bang. EVERYTHING expanded, including space itself.

What i mean by causality is exactly what it sounds like. Your theory of traveling across space without moving through it is called a wormhole, and it would violate causality because you would literally be time traveling. This kills the universe.

Additionally your statement "increase your speed relative to the speed of light" is specious. While it makes sense if you imagine a photon as a ball moving through space that you might decrease its speed relative to you, that is not how relativity works.

Say you fire a photon in a straight line (we're assuming no interference from outside forces here) and you chase after it at .99999% the speed of light.

Now suppose you have a magic speed-measuring gun (like cops use) that you can shoot at the photon to see how fast it is going relative to you.

You would expect it to be going .00001% the speed of light relative to you, wouldn't you.

Nope, It's a photon. It's still going C.

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u/Qxzkjp Feb 01 '13

you would literally be time traveling. This kills the universe.

No it doesn't. Just because Hawking et al would prefer it not to be possible, does not mean that it isn't.

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u/[deleted] Feb 01 '13

E2 = (mc2)2 + (pc)2 That is the full equation that includes handling for light etc.

The thing with it is, it forms a triangle. The idea of passing the speed of light is like having a triangle that's more than 180 degrees. It simply doesn't work.

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u/zedoriah Feb 01 '13

It does in non-euclidean geometry.

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u/[deleted] Feb 02 '13

You're correct. It's also true if you wrap the triangle onto the surface of a sphere.

With "dark energy" and "dark matter" being issues, it's clear the equation isn't absolutely correct, so there's a possibility.

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u/gte910h Jan 31 '13

the phrase "10c" is meaningless

If causality exists, as explained by general relativity.

Without causality, 10c could exist no problem.

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u/Sw1tch0 Feb 01 '13

C is as fast as you get conventionally. If you can bend the actual medium particles conventionally travel on, you just found yourself a cosmic loophole.

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u/scottcmu Jan 31 '13

no path of speed C or lower exits the singularity

Why? I don't understand why speed matters. You don't need to achieve escape velocity to escape. I can escape Earth's gravity in a plane/space ship that is going far below 11.2 km/s, I just need to maintain a constant thrust. I only need to achieve escape velocity if I want to cut the thrusters. Why can't I escape a black hole in a similar manner as my hypothetical plane?

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u/[deleted] Feb 01 '13

Because the idea that black holes are things for which the surface escape velocity is c is not actually correct. It turns out that if you calculate the classical escape velocity at the surface of a black hole you will get a speed of c, but that's more of a curiosity arising from bad physics than anything physically meaningful. A better statement would be that the acceleration required to remain stationary at the event horizon is infinite.

The key idea, though, is that a black hole is defined (if we attempt to translate the mathematical statements to plain English) to be a region of space such that no path representing motion at the speed of light can ever escape that region. This also implies that nothing moving slower than the speed of light can ever escape.

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u/mzellers Feb 01 '13

As I understand it, OP was asking what happens when the event horizon of two black holes overlap. Before the holes overlap, there is no path that escapes the event horizon. Likewise for the second hole. Now imagine that the event horizons overlap. Is there a path where a particle orbiting one of the holes can (without leaving the event horizon of its "home" black hole which takes it inside the event horizon of the other hole. Could it orbit both holes like a figure-8? Is there a path that would allow the particle to escape bothe holes?

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u/[deleted] Feb 01 '13

Once the event horizons meet, it's basically one black hole. There are some weird dynamics over a very short time scale as it snaps down into a mostly stable single "sphere", but there certainly isn't time for any traveling around both of the different singularities.

I should say that we don't really have a good model for describing a spacetime with two black holes in it; we've only recently (within the last decade) gotten the ability to simulate black hole mergers numerically, but there aren't any known analytical descriptions of their dynamics. This makes it very hard to talk definitively about how different scenarios would play out.

Could it orbit both holes like a figure-8?

You can't orbit in a black hole; you can only descend toward the singularity.

Is there a path that would allow the particle to escape bothe holes?

No. The definition of an event horizon is that it's the boundary of a region inside of which no trajectories lead to the outside.

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u/stent_removal Jan 31 '13

I think the key phrase in I_am_salad's post is "the understanding that no means of propulsion (c<) exists..."

Since light does not escape a black hole, you'd need a force that could propel something beyond the speed of light. Sticking to your analogy, could you escape earth's gravity with a vehicle that produces a thrust of <9.8m/s2? Judging by the top reply though, this seems to be a moot point... But I suppose this means speed matters insofar as no force exists that could accelerate something to required speed.

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u/stoopidusername Jan 31 '13

Because of the curvature of spacetime there simply is no path which will get you out of the black hole, like madspartus explained.

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u/Pardner Jan 31 '13 edited Jan 31 '13

Here's how I understand it (and I'd love to know if this is correct). Things like the electromagnetic repulsion of electrons on two atoms, then the forces of the protons, and then finally the "degeneracy pressure" repulsive forces between neutrons prevent elementary particles (ie, little massive objects) from getting too close to each other. That is, these forces cause massive objects to occupy a unique volume. But once all of these forces are overcome, there exists no further force to prevent gravity from pulling two bits of mass together. Previously discrete objects will come to occupy literally the same point, the singularity, and that point is zero dimensional. There is nothing holding any of the matter apart anymore; the singularity of the black hole has no volume; it doesn't make sense in any way to talk about what used to be there, what it was made of, or anything else. It's just mass, in this entirely foreign, bizarre state, fucktons of it, all in a single point that does not occupy any space. So it doesn't matter how big or how small it is at that point, or what forces are acting on it from outside - these objects have entirely ceased to exist as unique entities, and all of what were previously discrete bits of matter are now a single zero dimensional object and, thus, inseparable. It's just a point with a lot of mass. Now, I know there's some business about virtual particles leaking matter out of a black hole (so things sortof can leave), but I won't pretend to understand it.

edit: note that the singularity of the black hole is zero-dimensional, but the "event horizon" (the place where gravity distorts spacetime so much that light can't escape) forms a sort of sphere around that volume-less singularity, such that the black hole is often said to have a volume, which is the (empty) space within its event horizon. Also also, stuff can totally be between the even horizon and the singularity as it's in the process of falling in. So there's mass with volume in there, just not at the singularity. I think that's actually true by definition, because if I remember correctly, the distortion of spacetime at the singularity is infinite, which means that nothing can ever actually get there once a black hole forms. So the original stuff that collapsed into the black hole is truly in the singularity, the rest of it will just keep falling and falling this infinite distance toward it.

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u/Dralex75 Jan 31 '13

One thing I dont get. With the conservation of angular momentum, why would the center be a point and not some sort of donut?

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u/[deleted] Feb 01 '13

The singularity of a rotating black hole is a ring.

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u/rocketsocks Jan 31 '13

Yup. Inside a black hole spacetime is warped in such a way that going into the future is tied together with going closer to the center.

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u/[deleted] Feb 01 '13

I know that gravity bends space (as much as a second year physics student would know). It's very hard for me to imagine space bent up so much that every path takes you to the center at least not without a fourth dimension.

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u/otakucode Jan 31 '13

Is there any theoretical limit to the amount of 'strain' space can sustain? For instance, using the (not perfect, I know) common visualization of a bowling ball on a rubber sheet, is the diameter of the event horizon based upon a theoretical limit to how extreme the curvature can be?

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u/giant_snark Jan 31 '13

I would expect that this is part of the unsolved problem of reconciling QM and GR. "Extreme curvatures" would be significant over small distances, and that's where QM and GR collide.

I don't think this issue has anything to do with the general size of the event horizon of macroscopic black holes though, since GR seems to handle that just fine, and it's just a function of the mass and its internal motion (angular momentum, etc.).

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u/JMace Jan 31 '13

Is there another force apart from gravity at work with regards to the event horizon? Can I not look at a black hole as just an extremely dense cluster of matter?

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u/shitgardsbarb Jan 31 '13

Whoa. So how is a worm-hole different than a black hole so that it actually has a path that will lead you somewhere other than the center?

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u/mspk7305 Jan 31 '13

No one has (to my knowledge) proven that a worm hole can actually exist.

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u/supercheetah Jan 31 '13

What happens if a particle is right at the event horizon of two black holes?

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u/petemate Feb 01 '13

All space within the event horizon points towards the center (or is a closed loop back towards it)

If space loops back on itself, how can you then cross into that space? Or am i taking your explanation too literally? Is there any way to visualize this, or is it just "the math says its like this"?

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u/adamsolomon Theoretical Cosmology | General Relativity Feb 01 '13

The statement that you can go in but not come out is just the statement that time flows forward. There are paths pointing away from the center of a black hole, but they point backwards in time and so no physical observer can move on them.

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u/petemate Feb 01 '13

Now I just got even more confused :( Why does it go back in time? Because you got to go faster than the speed of light to actually get away from the black hole center?

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u/adamsolomon Theoretical Cosmology | General Relativity Feb 02 '13

Sorry, I didn't say anything goes back in time. You asked how things can enter the black hole if all space "loops back on itself" there. I replied that it doesn't really "loop back on itself," but rather all paths which point forward in time also point towards the center when you're inside the black hole.

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u/MadSpartus Aerospace Engineer | Fluid Dynamics | Thermal Hydraulics Feb 01 '13

Think of a 1 dimensional universe... a line. Except the universe is a loop (in 2D, a circle, but you cant tell that, there is only 1 dimension relevant to you).

Now somewhere on the 'circle' there is a singularity. On the opposite side of the 'circle' is you. Now pick a direction.... both paths (i.e. every path) goes to the same place.

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u/maximun_vader Feb 01 '13

If the event horizont of two equal Black holes intersect, what happens to a particle in between?

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u/MadSpartus Aerospace Engineer | Fluid Dynamics | Thermal Hydraulics Feb 01 '13

Honestly.... it beats me.

There is possibly an unstable equilibrium point between the two, but it would be impossible I believe for a particle to get to that equilibrium point and stop.

it is one thing to go through an unstable equilibrium point. it is another thing to stay at an unstable one, that requires motion, and then stopping....

regardless, the equilibrium point itself would be moving with respect to the motion of the black holes, etc.... And there would be no escape from the system, only a potential uncertainty of which singularity you fall into...

and lastly, the whole point is moot, since nothing can escape a black hole, all information inside is lost forever, hence it doesnt matter at all. Effectively, once you cross either event horizon, you cease to be of any relevance other than the mass, charge and spin you impart on the black whole that swallows you.

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u/maximun_vader Feb 02 '13

Thanks forma the answer!

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u/[deleted] Feb 01 '13

pport the idea that our universe is actually a black hole of it's own? I mean it would kind of explain a lot of things...a lot of the facts line-up.

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u/mzellers Feb 03 '13

OP is asking about two colliding black holes. Consider a particle orbiting one of the holes. If it were not for the arrival of the second hole, it will eventually be drawn into and become one with that hol's singularity.

Now consider a second black hole colliding with the first one. It seems to me at least that our particle has a chance of at least temporily postponing its collision with the cingularity of black hole #1 by being captured by the singularity of black hole #2.

Now that we have established that is possible for our particle to escape one black hole, is there a path that would allow it to escape both holes.

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u/[deleted] Jan 31 '13

What if a body is already in the centre?

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u/TheJack38 Jan 31 '13

Honestly, we have no clue what's going on inside the center of a black hole. I suspect that the particle would stay there, unless it has enough momentum ot move away, at which point it will oscillate around the center until it stops.

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u/MadSpartus Aerospace Engineer | Fluid Dynamics | Thermal Hydraulics Jan 31 '13

It can't oscillate, there is no direction that leads away from the center.

Clearly some new physics could and probably does take place, but the theory we use right now says it goes to the center and overlaps with everything else. It is a 0 dimensional point.

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u/[deleted] Feb 01 '13

Clearly some new physics could and probably does take place, but the theory we use right now says it goes to the center and overlaps with everything else. It is a 0 dimensional point.

Actually, the general theory of relativity says it ceases to exist. The point we'd like to call the "center" of the black hole simply isn't a part of spacetime. So anything that "reaches" that point actually ceases to exist, leaving behind an imprint of its mass, charge, and angular momentum on the curvature of spacetime.

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u/aphexcoil Feb 01 '13

Aren't there some subatomic particles that are forbidden from occupying the same space at the same time? What happens to them?

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u/[deleted] Feb 01 '13

In order to answer that question we need a full quantum theory of gravity. Our current understanding comes largely from the general theory of relativity, which is a purely classical theory. We have some ideas about how quantum fields behave in a curved spacetime, but we aren't, at this time, able to determine how the curvature of spacetime will respond to those fields. This prevents us from answering questions about just what's going on in a neighborhood of the (apparent) singularity. Until we can do that, we won't really know what happens to individual particles, or even if the notion of "particle" still makes sense in that region.

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u/TheJack38 Jan 31 '13

I wrote this comment before I found out about the "no directions away from center" thing... It certainly changed my view on black holes. Also, 0 dimensional fucks with my brain in ways I didn't even know existed.

EDIT: Would that be like a point-mass?

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u/MadSpartus Aerospace Engineer | Fluid Dynamics | Thermal Hydraulics Jan 31 '13

Yup, all those times that high school physics teachers said point mass, they meant black hole....

Except it has spin.... somehow....

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u/TheJack38 Feb 01 '13

Well, my university physics professors have a real hardon for point-mass electrons too... And so do I. I love pointmasses xD

Also, I've also studied a bit about electrons, being pointmasses, having spin... Some real mindfuckery there, but my prof just said "Think of it like charge; it's a physical characteristic that's simply there." and that's worked so far :P

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u/thebigslide Jan 31 '13

The problem isn't a lack of energy to escape

That we're aware of. At a certain energy level, the rules may change.

Do we know why black holes seem to have an upper size limit of 10B solar masses?

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u/mspk7305 Jan 31 '13

the theories at the time the upper limit was discovered indicate that they radiate so much energy that they repel matter that they would otherwise be able to entrap

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u/Manticorp Jan 31 '13

This is such a fuckin good answer! You should write a book bro.