Effects of Warped Time in Black Holes on the Black Hole Itself

[Dres]

Okay, so here is my question. *NERD MODE ENGAGE*

So, as some of you know, high gravity fields can warp time, due to the effects of relativity. This effect is so extreme near black holes, due to their gravity, that an hour close to a black hole can be a thousand years on Earth. Now, as an observer falling into the black hole, as you looked out you would see, in the little disk that is the universe around you (gravitational lens effects) you would see it aging and dying, faster and faster, until you pass through the event horizon.. Once you passed the event horizon, you wouldn't notice anything different, you would just keep falling until you are spaghettified by the gravitational forces. However, at this point, you are closer to the singularity than the virtual particles around the event horizon. These are the particles that contribute to Hawking radiation, and eventually cause the black hole to be destroyed. As you are closer to the singularity of the black hole than the virtual particles at the event horizon, they will experience a faster time than you do. Thus, you would expect the black hole to be destroyed as the particles take away its mass faster and faster from your point of view, possibly even before you are spaghettified. Therefore, you would be witness to the death of the black hole, and would likely be killed in the final explosion, due to the effects of the black hole itself.

Whew, that was an explosion of science. *NERD MODE DISENGAGE*

[Dedjal]

Time does not quite work like that, though.

Picture a rubberband. You can stretch it, twist it etc. But as soon as you let go of the tension, the rubberband return to its original state (unless you tie a knot on it, but that is excluded for now).

Time works in much the same way under tension.

So a black hole can twist time. But a second will not become an hour for the person inside the black hole. It would still only be a second. For the viewer, it could be an hour.

But the person inside the black hole would die before seeing much of anything.

[K^2]

Hm. This is a very interesting question. Large black holes evaporate very slowly. In fact, they are growing faster than they can evaporate from background radiation alone. It takes a very tiny black hole to evaporate. But that's now. As the universe expands, both matter and radiation are going to become less available for black hole to grow, while evaporation rate remains constant. Eventually, there should be a point that even large black holes start to evaporate.

The other point is that it takes a supermassive black hole for you to fall into intact. That spagettification starts to happen pretty early for smaller black holes. You'll be ripped into atoms before you cross the horizon. But supermassive black holes have quite reasonable tidal forces near the horizon. A ship can fall in intact.

If universe expands without limits, any black hole will evaporate in finite time. Mind, it's going to be absurdly long time, one which makes current age of the universe seem like a fraction of an instance. But finite nonetheless, and there is no indication that there is some sort of a grand time limit on the universe. Even if protons start decaying, black holes should be fine. So as you fall into the black hole, you must pass that threshold. You must reach time of that black hole's eventual end.

But therein lies the paradox. If this is supposed to happen in finite time, it will happen before you reach event horizon. That brings up a whole lot of problems. a) You can't actually fall into black hole, because it will evaporate before you get there, but you won't get out alive either because Tidal forces will increase as it shrinks, and if that's not enough c) It will blast you with an ever increasing dose of Hawking Radiation.

None of this sounds right, so there must be a flaw in one of the assumptions. I will take another look at statement of Hawking Radiation, and see which coordinate system it's actually always finite in.

[Bryce Ring]

Curious. Since when have Black holes been known to evaporate ?

[Dres]

Well, I was thinking about this, mainly about the fact that as you are falling in, the black hole is evaporating faster and faster from your point of view, so it must evaporate completely before you reach it, and I came up with something quite interesting. As you are falling towards the event horizon, the region of space that is closest to the horizon, the place where the virtual particles that matter would form, would appeared drastically slowed. This is because they are obviously closer than you are to the black hole. But does the time dilation of this region actually effect the formation of the particles from the vacuum energy? If it does, than to any observer outside of the event horizon, unless they are at it, would see the particles forming more slowly, and thus it would take even longer for the black hole to evaporate. And, If you are, once again, an observer falling in, than the black hole would decay more slowly than usual until you pass beyond the tiny layer beyond it, and unless time dilation is significant over such small distances, you would fall into the black hole possibly before it decays.

That last part also brings in the question: Will the time dilation increasing as you get closer and closer to the black whole kill you anyway, as different parts of your body have different clocks?

[Bill Phil]

For a while. It was proved that they aren't perpetual, which would have defied the laws of physics. So they release Hawking Radiation and lose mass over time, if they have no mass to consume. That's all I know, though.

[Dres]

For Bryce Ring:

Steven Hawking proved that black holes evaporate. The idea is that pairs of virtual particles, an example being a positron and an electron paired, pop into existence because their energy is borrowed from the vacuum, and then annihilate soon after. However, if these particles form close enough to a black hole, the antiparticle can fall into black hole, and the other particle escapes to infinity. From an outside observer's point of view, the black hole will have emitted the particle. Smaller black holes will evaporate faster because of things to do with smaller operational surface area of the event horizon and the black hole's mass.

[K^2]

I wouldn't say it was proven. Hawking has shown that field theory suggests that black hole can emit a particle by interacting with particle-antiparticle pairs near the event horizon. That brought up a whole lot of questions, but it's a fairly accepted position now. Naturally, if black holes don't actually evaporate, then the question has no meaning, so we are having this discussion under assumption that Hawking is, indeed, right about this radiation.

As far as experimental verification, Hawking Radiation remains unconfirmed. Though, there have been some experiments that have detected radiation which fits the pattern. So we might have confirmation of it soon as more data is gathered.

[Bill Phil]

Well, if they are perpetual we might have to rethink the laws if physics...

[Whirligig Girl]

Black holes are not ALWAYS completely deadly. The biggest of them have a gravitational attraction at the event horizon of only a few Gs, IIRC. But then, I heard this from a History Channel documentary, so who knows if that actually makes sense. Right about now, upon realizing that something might not make sense, I would devote a half hour to two hours to trying to understand exactly how the effects work, but I'm in pain and I'm tired, so that will have to wait for tomorrow.

[K^2]

Well, if they are perpetual we might have to rethink the laws if physics...

Why? They don't use up any energy. Having something that exists forever is not the same thing as having a perpetual motion machine. The term's misleading, but if there is no net energy output and no net entropy decrease, then it is not a violation.

[Bill Phil]

Why? They don't use up any energy. Having something that exists forever is not the same thing as having a perpetual motion machine. The term's misleading, but if there is no net energy output and no net entropy decrease, then it is not a violation.

Perpetual means they go on forever. They don't use energy, true. But they do absorb it.

If they only take in matter, and don't release energy, it doesn't have any thermal energy that can be output as work. Then it only has entropy. And then, its entropy couldn't rise. But its thermal energy is released and it loses it over time, so it does gain entropy.

[Dres]

For K^2: Yeah, there has been no concrete proof for Hawking Radiation. There have indeed been tests to find evidence of an evaporating black hole, specifically one in its final death throws, in order to find evidence for primordial black holes. However, we do know that subatomic black holes have formed in the LHC (probably/maybe), and they appear to have evaporated.

- - - Updated - - -

For Bill Phil: You are correct about the thing with entropy. Black holes would violate the laws of thermodynamics (I'm pretty sure that you people know what they are) because they appear to decrease entropy in a supposedly closed system, the universe. Thus the universe is not a closed system, or black holes radiate something.

P.S. If anything in here is incorrect, I'm sorry. I don't remember everything from all of my physics books and A Brief History of Time.

Edited January 4, 2015 by Dres

[rkman]

But therein lies the paradox. If this is supposed to happen in finite time, it will happen before you reach event horizon. That brings up a whole lot of problems. a) You can't actually fall into black hole, because it will evaporate before you get there,

As seen by an outside observer, not as seen by the person falling in..?

[Dres]

As seen by an outside observer, not as seen by the person falling in..?

As seen by the person falling into the black hole. If you were an outside observer, everything would be normal, there would be no time dilation, unless of course the outside observer was travelling close to the speed of light.

Edited January 4, 2015 by Dres
Spelling

[AngelLestat]

Hm. This is a very interesting question. Large black holes evaporate very slowly. In fact, they are growing faster than they can evaporate from background radiation alone. It takes a very tiny black hole to evaporate. But that's now. As the universe expands, both matter and radiation are going to become less available for black hole to grow, while evaporation rate remains constant. Eventually, there should be a point that even large black holes start to evaporate.

From what I understand, if we have a particle with its antiparticle in the edge of the black hole, then there is the chance that one falls, and the other dont. This phenomenom extracts energy from the black hole it self. So this happen more often if the black hole is small, because tidal forces at the edge are stronger, so evaporate faster. At least this is something that I read long time ago. So correct me if I am wrong.

But therein lies the paradox. If this is supposed to happen in finite time, it will happen before you reach event horizon. That brings up a whole lot of problems. a) You can't actually fall into black hole, because it will evaporate before you get there, but you won't get out alive either because Tidal forces will increase as it shrinks, and if that's not enough c) It will blast you with an ever increasing dose of Hawking Radiation.

None of this sounds right, so there must be a flaw in one of the assumptions. I will take another look at statement of Hawking Radiation, and see which coordinate system it's actually always finite in.

Now there is another hypothesis about what might happen if we fall in a black hole.

You hear about the firewall solution to solve the black hole paradox?

In brief, it said that if you fall into a black hole, when you reach the event horizon you crash against this firewall, which may sound ok from the perspective of one outsider, but difficult to understand if that really happens to someone who is falling.

Although many scientist take this like an example that our theories are wrong (even for describe the edge of a black hole), but right now; they can not find the error with the firewall hypothesis.

http://www.scientificamerican.com/article/black-hole-firewalls-confound-theoretical-physicists/

[Dres]

That was a very interesting article. Wow, its an intriguing concept, the firewall. I'ma have to take a break from watching theories about resolving quantum gravity.

[AngelLestat]

I would love to see this hypothesis to be proven wrong.

Being close to a black hole is equal to see the edge of our universe. Something that I think we can not see in other way. So cross it means the chance to leave this universe.. Now if we learn that we can not.. Then it means that we are confine to this universe for always. So is not a good feeling.

[YNM]

Regarding firewall, the link mentions equivalence (principle). Equivalence is an important feature, even relativity arises from thoughts about it - but I think what's more important is causality. As long as light still travels well, causality should be in effect, no ? I mean, if a particular event cannot be linked to other event (no meeting of worldlines), then nothing would be in effect with each other. What I often accepts is that while one falls in, it'd not be able to see anything (ie. no photon) to the direction of the singularity, while away from it, one can still see what's outside. So safe to say he might see the universe evolve off, while the central singularity stays. The paper itself mention eigen-thingies from start, maybe if one can understand it...

Nobody can be sure through. There's no TARS to research and tesseract to transmit...

[Skyler4856]

Since your perception of the universe is slowed down, you wouldn't be able to view the universe end, nor would you be able to view the black hole dissipate

[Dres]

Since your perception of the universe is slowed down, you wouldn't be able to view the universe end, nor would you be able to view the black hole dissipate

Quite the contrary. Your perception of the universe is actually sped up immensely. It's confusing, but because you have a slower clock than the rest of the universe, the rest of the universe would see you slower, but you would see the universe faster.

[Skyler4856]

Quite the contrary. Your perception of the universe is actually sped up immensely. It's confusing, but because you have a slower clock than the rest of the universe, the rest of the universe would see you slower, but you would see the universe faster.

What?! That's fallacious reasoning; an observers clock dictates any and all reactions, including those that occur in his head...

[Dres]

Here, let me explain more thoroughly. Your time is warped, so your clock runs slower than the rest of the universe's clock. However, from your point of view, your clock is running at normal time. Thus the rest of the universe is travelling through time faster than usual. Now, near a black hole, the effect is so extreme that the universe dies as you reach the event horizon, due to gravity. It also brings into being the question that this discussion is based on.

[Skyler4856]

Here, let me explain more thoroughly. Your time is warped, so your clock runs slower than the rest of the universe's clock. However, from your point of view, your clock is running at normal time. Thus the rest of the universe is travelling through time faster than usual. Now, near a black hole, the effect is so extreme that the universe dies as you reach the event horizon, due to gravity. It also brings into being the question that this discussion is based on.

I understand your reasoning, however, you must realize that ALL processes run slower, not just some imaginary clock. Your question only has meaning if one assumes perception of time to be independent of perception of the universe

[YNM]

I understand your reasoning, however, you must realize that ALL processes run slower, not just some imaginary clock. Your question only has meaning if one assumes perception of time to be independent of perception of the universe

Atomic clocks on GPS sats are designed to be slower (uh, more caesium atom transitions to count the second probably) than the standard one on Earth. This does have to do with the fact that the sats lies on a site where spacetime is less curved than on the Earth's surface (general relativity term ; else, on a shallower/higher gravitational potential by newtonian terms).

The result ? you got these things points out your location to a high accuracy !

The same then applies to other sites...

Edited January 5, 2015 by YNM