Slashdot Mirror
Black Holes Don't Trap Information Forever
sciencehabit writes "New calculations suggest that black holes are not a one-way street. Anything that falls into them may eventually come out. The findings lend important support to quantum gravity, but fly in the face of Einsteinian relativity. They also support Stephen Hawking's reluctant admission that information couldn't be destroyed by black holes. Penn State researcher Ahbay Ashtekar was quoted saying, 'Once we realized that the notion of space-time as a continuum is only an approximation of reality, it became clear to us that singularities are merely artifacts of our insistence that space-time should be described as a continuum.' Let the physics infighting begin."
Actually, the energies involved are so low that a black hole created would be small enough to pass between two atoms in solid matter with huge margins, so most likely it'd just zip trough earth as if it was vacuum. And given that the particles involved have energies equivalent to 99.999% of lightspeed or thereabouts, you'd have to be IMPOSSIBLY precise to NOT have a velocity higher than 11km/s. In short, if the holes didn't evaporate, they'd simply zip trough earth and leave for outer space, more likely than not never swallowing even a single electron, and doing no damage whatsoever.
I wouldn't call quantum theory ugly, just counter-intuitive, and that, I think, comes from the fact that at our magnification level, we don't see anything that behaves quite like anything at quantum level.
The most insightful thing I've ever read on that is Feynman's introduction to quantum theory:
Tie two birds together: although they have four wings, they cannot fly. (The blind man)
You remind me of what Lord Kelvin was telling his students 100 years ago. Something like: "I'm sad for you, since the Physics is now complete" . Just after that sentence, quantum physics and relativity were discovered ;-)
Herve S.
In the mean time, a reasonable stab at an intuitive understanding is that two particles of unknown state are entangled when the examination of one reveals the state of both.
The "spooky" things about entanglement are that (a) the unknown state can persist for long time intervals and (b) the quantum states of one of the particles cannot be fully described without knowing the quantum states of the other. Part of the "(b)" problem is that fully describing one particle automatically therefore fully describes the other.
Another problem is that absent full knowledge of the local piece of the entangled pair limits the amount of knowledge one has of the entire local system, possibly in significant ways (Schroedinger's cat). A remote viewer who "collapses" the pair can know about a massive local change, even if the distance is such that the remote viewer cannot communicate the full quantum state because of the fundamental information sharing speed limit (speed of light in vacuum).
In classical world, this is like having two synchronized long-running count down timers, one of which is attached to a bomb that is transported a long way away. When the local clock reaches "0", one reasonably believes that the bomb has gone off, even if the news confirming that will take some to arrive.
The difference is that in classical world there are lots of ways in which the remote bomb might not go off at all (or precisely at "local 0"). In entanglement experiments, the observation of local state invariably triggers simultaneous collapse of the remote system. There is no completely accepted explanation for this.
We don't know.
We don't know what that will do either.
No, that is not clear. If they remain entangled you simply know the full motion of the other half of the entangled pair within the black hole system. Since you don't really know anything at all about the black hole system, that doesn't really cause information leakage problems. Likewise, if dropping half of an entangled pair into a black hole breaks entanglement, there is no information problem, since you do not really know anything about the black hole system. That is, the black hole system is not really using its half of the entangled pair as a "trigger" for timing something inside or outside the black hole system.
This sort of thing was thought about with the Unruh effect and Hawking radiation. Whether the entangled partner pops out of the black hole "eventually" still entangled or not could take a very very long time to be testable in principle...
With a microscopic black hole you could throw entangled pairs at it, wait for it to evaporate, and then try to interrogate the "uneaten" halves to see if they have collapsed. This is plausible. Sean Carroll discusses this sort of quantum interrogation here: http://cosmicvariance.com/2006/02/27/quantum-interrogation/
Rephrasing:
Now we simply replace "there is a puppy in the box" with "there is one partner in an entangled pair which has been evaporated out of the MBH".
The creation of useful MBHes interacting usefully with useful fields of entangled pair halves is an exercise for the reader.