17 July 2004

Black, like my ... well, you know

Next Wednesday, Stephen Hawking will present a talk at the 17th International Conference on General Relativity and Gravitation in Dublin. At the last minute for applications, he sent a note to the group chairing the scientific committee for the conference that I have solved the black hole information paradox and I want to talk about it. This was originally reported in a New Scientist article. The information paradox states that the quantum information of particles lost in a black hole is never returned to the universe because the information contained in the particles returned is different (and, in a way, empty). That loss of information screws up quantum determinism: we would have to admit a greater randomness into the universe. It's a philosophical admission, but science has always defined our philosophical understanding of the universe.

If Hawking's hour-long presentation convinces the attendees, He and Kip Thorne of Caltech will lose the bet they made with John Preskill of Caltech. In it, the loser(s) will reward the winner(s) with an encyclopedia of the winner's choice, from which information can be recovered at will.


Anyway, the math is beyond me, but Brian Greene touches on the issue in his book The Elegant Universe.

Here's Greene's explanation (with liberal quoting):

The concept of the clockwork universe was derived, exhaustively, from Newton's laws of motion. The results were that:

If at some instant you know the positions and velocities of every particle in the universe, you can use Newton's laws of motion to determine--at least in principle--their positions and velocities at any other prior or future time. From this perspective, any and all occurrences, from the formation of the sun to the crucifixion of Christ, to the motion of your eyes across this word, strictly follow from the precise positions and velocities of the particulate ingredients of the universe a moment after the big bang.

However, because of the deterministic problems with quantum particles, this hypothetical ability to know all particles' positions and velocities and therefore to determine previous and subsequent states of the universe is flawed. Quantum particles don't give up their positions and velocities with absolute values. This is the quantum uncertainty that is thrown around so much, and so poorly, in pop culture.

(For reference, here are charts I put together some time back of the standard model particles: Force Particles and Matter Particles.)

The clockwork universe becomes a probability universe. Wave functions--the probability waves of quantum mechanics--evolve in time according to precise mathematical rules ... This informs us that quantum determinism replaces Laplace's classical determinism: Knowledge of the wave functions of all of the fundamental ingredients of the universe at some moment in time allows a vast enough intelligence to determine the wave functions at any prior or future time.

The wave function, or probability wave, encodes the probability that a particle will be found at a given location.

So the information paradox asks: does the information contained in the things swallowed by the black hole--the data we imagined existing within the black hole's interior--re-emerge as the black hole evaporates? This is the information required for quantum determinism to hold, and so this question goes to the heart of whether black holes imbue the evolution of our universe with an even deeper element of happenstance.

Hawking's paper will argue that information can escape from the black hole.

[ posted by sstrader on 17 July 2004 at 9:59:58 AM in Science & Technology ]