At 10:42 PM -0600 1/27/98, Jim Choate wrote:

Forwarded message:

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Date: Tue, 27 Jan 1998 20:34:48 -0800 From: Tim May <tcmay@got.net> Subject: Re: Planetary rovers, SETI and other musings, was Re: update.356 (fwd)

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Nothing in quantum teleportation has been shown to propagate signals faster than light. (If you don't believe me, look into it. Start by reading the FTL discussions about Bell's Theorem.)

The actual transportation of the state is instantanious as it must be by quantum theory, just as the change in orbits of an electron occurs instantly. However, the catch is that the command/synchronization channel must be sent in parallel and it at some point can't use the quantum transportation technique and hence the speed-of-light comes back into play. This was specificaly discussed in the original quantum transportation announcement sent out by AIP.

I don't understand why a command/synch channel is required. Why aren't the coding techniques commonly used in telecom and disk data encoding adequate to both synchonize and convey data? --Steve

Steve asked in another message about where one learns about some of this stuff. As always, "Scientific American" is a good place to look for articles. They've had many articles on Bell's Theorem, nonlocality, the EPR paradox/nonparadox, the Aharanov-Bohm results, and quantum teleportation. A SciAm article will explain, with pictures, in ways we can't here. (Plus the articles are carefully written, by experts--we waste too much time here getting lost in misunderstandings about the meanings of terms of art.) "Science News" is sometimes good, too. And "New Scientist" and "Nature." Any library should have plenty of articles. There are also dozens of popular books on these subjects, ranging from "In Search of Schrodinger's Cat" to "Where Does the Weirdness Go?" And the Web of course has vast resources. Just taking a glance, I see 2000 hits on "quantum teleportation" with HotBot. And 200 hits on "faster than light communication," for example. Other, more refined searches are trivial to do. Some of these articles are reviews, some are primers, some are pointers to more info. Anyway, back to "quantum weirdness," which, so far, has not looked very weird. (To me, at least. But, like most physicists, it seemed weird to me at first but then became "just the way things are" after a few months.) At 9:20 PM -0800 1/27/98, Steve Schear wrote:

I don't understand why a command/synch channel is required. Why aren't the coding techniques commonly used in telecom and disk data encoding adequate to both synchonize and convey data?

Imagine a pair of photons sent in opposite directions. With different polarizations, but "tangled." Observer A measures a polarization of "1." He then knows that Observer B will measure "0." All that is revealed is a _correlation_, a kind of structure built into the Universe. Interesting, but not so weird as it seems. (And this is not any kind of "action at one site instantaneously changing the state far away." No more so than sending two envelopes out, one with a "1" inside and the other with a "0" inside changes things instantaneously.....) No signal sending is possible because neither observer can "change" the polarization of a photon. They can certainly pick a sequence of photons to measure, and thus get various polarization values. But it can't send a "message" to the other site because the series of photons picked forms the key, and that key must itself be sent. Similarities to one time pads, obviously. More info in the sources named. Avoid the pop science treatments by Nick Herbert, unless other, more mainstream sources are also consulted at the same time. And definitely avoid the "psi" nonsense of Jack Sarfatti. Gribbin's books are pretty good. --Tim May The Feds have shown their hand: they want a ban on domestic cryptography ---------:---------:---------:---------:---------:---------:---------:---- Timothy C. May | Crypto Anarchy: encryption, digital money, ComSec 3DES: 408-728-0152 | anonymous networks, digital pseudonyms, zero W.A.S.T.E.: Corralitos, CA | knowledge, reputations, information markets, Higher Power: 2^2,976,221 | black markets, collapse of governments. "National borders aren't even speed bumps on the information superhighway."