[chimera (OP)]

It's supposedly impossible to change the information inside a black hole, I take it?

Anybody care to explain?

[Ultima]

Surely you can but you would never know about it?

wOw the world spins?

[chimera (OP)]

If it's possible to create a virtual pair of particles, send in one and observe what happens to the other. If you change the twist on one, if the 'link' is still intact, the other particle cannot but do the same thing, according to QM.

The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[Ultima]

meh entanglement [], I can never get my head around it, what carries the information how does it propagate and how fast? Or is it that they are the same particle just present in two places in space?

wOw the world spins?

[DoctorBeaver]

quote:Or is it that they are the same particle just present in two places in space?

NOOOO... don't do that to me! [xx(]

[DoctorBeaver]

"Black holes have no hair", n'est-ce pas?

The way I interpret that is that there is no way of knowing what has gone into a black hole - be it a star, a sofa or the complete works of Shakespeare - unless you actually observed it going in (but wouldn't time-dilation mean that you would never actually see it enter? WOuldn't you see it stuck forever at the event horizon?). Sure, you can send in a particle & observe its twin. But if you do something to affect the particle you're observing there is no way of ever knowing if that has affected the particle you sent into the black hole.

It wasn't me - a big boy did it & ran away

[chimera (OP)]

quote:Originally posted by DoctorBeaver

"Black holes have no hair", n'est-ce pas?

Sure, you can send in a particle & observe its twin. But if you do something to affect the particle you're observing there is no way of ever knowing if that has affected the particle you sent into the black hole.

When Einstein was asked what he thought of the results of the Michelson-Morley experiments, he said it was nice to have it corroborate his theories, but if it hadn't he would not have cared, but would have felt sorry for the observers.

If there is nothing that destroys the link between the two particles, what happens to one, MUST happen to the other, and instantaneously (action at a distance). So there is no need to check, Albert would say. It cannot be different.

[DoctorBeaver]

But how could we ever know if that link still existed? Sure, if the particle we were observing threw a wobbly, we could say that something had happened to the particle inside the hole to cause it. But there is absolutely no way of knowing if the particle outside the hole still has an effect on the 1 inside

[chimera (OP)]

Well, it all hinges on that link, and I understand from QM-cryptography that it's a pretty fragile one, but that is of course our current level of understanding. If you can do it, you'd have a way of 'tweaking' a black hole at a distance.

The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[DoctorBeaver]

Yeah, I accept that. But how could you ever know if that tweaking had worked?

[gsmollin]

Einstein was not a QM researcher, and did not agree with a lot of its findings.

Entangled particles retain their link when separated. However, any disturbance to the link will cause the stae to resolve. You can't look at it without resolving it. But its not just you. No other fermion or boson may interract with the entangled particles without resolving the state.

If one fell into the black hole, it would resolve the state, since it would interact with the event horizon. This would resolve the state, and you could look at the one. The other would be frozen at the event horizon, in the same state.

[chimera (OP)]

Ah, meaning you can receive 'information' from a black hole? Any resolution of the state would be transferred 'information' despite the black hole being an absolute gravity pit with no return? Only the information would be useless, right?

Unless of course the mini-black hole (let's stay realistic here) could be *entirely* built up of halves of virtual pairs, meaning you can control its growth both ways because you are in fact creating it with its own Hawking radiation, which you can put a stop to or speed up at will. The state of the black hole could then be 'read' in the cloud of particles around it, and hey, maybe we have our first intergalactic tincan-and-wire gravity phone? Who knows? Any disturbance inside the black hole not by your hand would constitute an actual phenomenon begging to be investigated, I guess.



The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[Ultima]

What if you had a black hole that was comprised of only entangled particles? Could you control the behaviour of the black hole []
Never know they might be able to do something like this at CERN in 2010 [] YAY Science!

wOw the world spins?

[gsmollin]

quote:Originally posted by chimera

Ah, meaning you can receive 'information' from a black hole? Any resolution of the state would be transferred 'information' despite the black hole being an absolute gravity pit with no return? Only the information would be useless, right?

Unless of course the mini-black hole (let's stay realistic here) could be *entirely* built up of halves of virtual pairs, meaning you can control its growth both ways because you are in fact creating it with its own Hawking radiation, which you can put a stop to or speed up at will. The state of the black hole could then be 'read' in the cloud of particles around it, and hey, maybe we have our first intergalactic tincan-and-wire gravity phone? Who knows? Any disturbance inside the black hole not by your hand would constitute an actual phenomenon begging to be investigated, I guess.



The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

No information came from the black hole. I said the particle would be frozen at the event horizon. Any particles that enter the event horizon appear frozen there because of time dilation. The real particle passed through the event horizon and is now lost.

[DoctorBeaver]

quote:If one fell into the black hole, it would resolve the state, since it would interact with the event horizon. This would resolve the state, and you could look at the one. The other would be frozen at the event horizon, in the same state.

I've got to think carefully how to try to word this as I'm not sure I understand myself what I'm trying to say here.

Because of time dilation 1 of the pair of particles (call it p2) is frozen at the event horizon. To an outside observer it will never pass it. So could the link still affect it when the 2 timeframes are so very different? Twiddling the free particle (p1) only takes a tiny fraction of a second -  a finite time. But by the time you transfer that fraction of a second to the event horizon, it becomes an eternity. Does it not follow, therefore, that to the observer of p1 it would take an eternity for p2 to be affected even though the event only took a fraction of a second from the perspective of p2? In other words, it could never be observed from p1?
Or how about reversing that? If an event affects p2, would the cause of that event take an eternity to happen from the pespective of p1 even though it was only a fraction of a second to p2? So, again, surely it would never be observable because it would take an infinite amount of time for p1 to be affected.
Time dilation does my head in. I'm going for a lie down! [xx(]

[gsmollin]

That's a good point. We might not see it after all. This would depend on the exact timing of the resolution. If it occurred soon enough we could see it, but its entirely possible it might not be visible because of the time dilation. It may resolve, and we can't be sure because we're seeing one particle at normal time, and have to wait an eon to see what happened, if anything, from the other. It is also entirely possible that the whole particle could disappear from gravitational redshift before it passes the event horizon.

There are a host of tricky results from the realtivistic physics surrounding a black hole, and that's without adding quantum mechanics. Remember we don't even have a cohesive theory about this, let alone the ability to solve the equations.

[DoctorBeaver]

Whoooaaaa - did I actually manage to say something sensible? I feel quite chuffed now [^]

[DoctorBeaver]

quote:It is also entirely possible that the whole particle could disappear from gravitational redshift before it passes the event horizon

Could that actually happen? Would it be that the pull of gravity would totally drain its energy so it just went phut?

[DoctorBeaver]

gsmolin - You don't say in your profile... are you a physicist?

[gsmollin]

quote:Originally posted by DoctorBeaver

quote:It is also entirely possible that the whole particle could disappear from gravitational redshift before it passes the event horizon

Could that actually happen? Would it be that the pull of gravity would totally drain its energy so it just went phut?

The gravitational redshift would stretch the wavelengths so the particle might not be visible. You can't see an electron unless the radiation has a wavelength shorter than the size of an electron.