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Comment by Chris5 on Excluding the Supernatural · 2008-09-12T02:20:56.000Z · LW · GW

Phil: Vampires ARE real. Both humans and animals can become vampires after being bitten by another vampire (very often a bat or racoon). After being bitten, they will go crazy and attempt to bite others. They also are unable to cross running water.

The virus has been discovered, and a vaccine exists.

http://en.wikipedia.org/wiki/Rabies

Yeah, I know, those aren't "real" vampires, even though that is very likely the source of the vampire mythology.

Comment by Chris5 on Decoherent Essences · 2008-04-30T16:20:20.000Z · LW · GW

Psy-Kosh: in the basis of eigenvalues of the Hamiltonian, not only is the equation local, but nothing even moves.

Comment by Chris5 on The Quantum Arena · 2008-04-15T20:46:36.000Z · LW · GW

They do not describe, even in principle, how one configuration develops into another configuration.

I'm going to just clarify this point, which I disagree with as written (not strictly wrong, but it overlooks something important). You can make a minor extension to quantum mechanics that does describe how one configuration develops into another. That extension is Bohmian mechanics, which is empirically equivalent to orthodox QM.

Basically, you postulate that in addition to the wavefunction, there is a configuration, and it obeys a certain law of motion which is guided by the wavefunction (the law is "switch to the hydrodynamic formulation change of variables, use the velocity law there").

If you additionally postulate that the initial configuration is unknown, but randomly distributed like |psi(x)|^2 dx, you completely recover quantum mechanics. Among other things, you'll never remove the initial uncertainty in a system governed by quantum mechanics.

So in fact, quantum mechanics is fully consistent with the existence of a single configuration.

However, that configuration alone doesn't fully determine the future; you still need the wavefunction for that.

I'm not really one of the "true believers" (some folks fanatically love it), but I find it to be extremely helpful in developing intuition/doing calculations. (Note: remove all hints of Bohmian mechanics before attempting to publish.)

Comment by Chris5 on Where Philosophy Meets Science · 2008-04-14T02:29:03.000Z · LW · GW

Jess: I can give you the standard references (which you've probably already seen), but they are mostly useless. This is a really weird field to work in, I'd strongly recommend against making a career of it. Tough to find jobs for rather stupid political reasons.

The only really useful work is a paper about measurement by David Bohm from the 50's (don't have it with me). He describes decoherence/measurement in words, and his explanation makes sense. It's good to get an intuitive picture, but not for much else.

Apart from that, all I can suggest is that you build a toy model of a quantum system X observation device and solve it. That will explain far more than any paper I've ever read.

Comment by Chris5 on Where Philosophy Meets Science · 2008-04-12T23:19:50.000Z · LW · GW

Sometime last year, I got involved in studying foundations of quantum mechanics. Like many people before me, I rediscovered decoherence. (In my case, the context was a heavy atom interacting with Bose-Einstein Condensate.)

After I discussed my work with one of our resident experts in the topic, he pointed out to me that David Bohm had made the same argument (in words, not mathematically) in the early 1950's. In fact, the idea had even been present before that, though Bohm's explanation is the best of the early ones. He postulated the following explanation why the Copenhagen interpretation became the dominant one: the Copenhagen crowd had more Ph.D. students, and network effects (Copenhagen people becoming editors at PRL, for instance) pushed a nonsensical theory into the mainstream.