In 1996 IBM came out with an ad that made a remarkable claim. It says an IBM scientist and his colleagues have discovered a way to make an object disintegrate in one place and reappear intact in another. Beam me up, Scotty! Is this a publicity stunt? Is it true? They say there's a teleport exhibit on their Web page at http://www.ibm.com/news/ls960202.html (page no longer available) and give a phone number as well. Can't get through. Can you?
Publicity stunt? What makes you think somebody placing full page ads in the New Yorker could possibly be interested in publicity? The more pertinent question is whether the bit about teleportation is true. The answer is, well, sort of. But don’t sell the moped yet.
Let’s look at that ad. After a bit of nonsense about Margit telling her E-mail pal Seiji she’s going to teleport him some goulash, the ad says their plans are “a little premature, but we are working on it. An IBM scientist and his colleagues have discovered a way to make an object disintegrate in one place and reappear intact in another. It sounds like magic. But their breakthrough could affect everything from the future of computers to our knowledge of the cosmos.”
The IBM Web page refers us to an article entitled “Teleporting an Unknown Quantum State Via Dual Classical and Einstein-Podolsky-Rosen Channels” by Charles Bennett et al. Ideally you want an article like this to start, “Get two D-cell batteries and some string …” Never the way. The abstract begins, “An unknown quantum state … can be disassembled into, then later reconstructed from, purely classical information and purely nonclassical Einstein-Podolsky-Rosen (EPR) correlations.”
OK, maybe a practical guide to teleportation was too much to hope for. Still, as we read on, the suspicion forms that perhaps the copywriters didn’t read the article before writing the ad, or if they did, didn’t understand it. On page two Bennett and company write, “It must be emphasized that our teleportation, unlike some science fiction versions, defies no physical laws. In particular, it cannot take place instantaneously. … The net result of teleportation is completely prosaic: the removal of [a particle having a certain quantum state] from [one person’s] hands and its appearance in [someone else’s] hands a suitable time later.” In other words, you could accomplish the same thing with Federal Express — except that FedEx lets you transport more than one particle at a time.
Don’t get me wrong. Bennett and company’s quantum teleportation (Q-TP) is subtle and ingenious (way too subtle and ingenious to explain in an 800-word column — check out their article if you need to know more). But there’s no necessary connection between Q-TP and science fiction TP. Q-TP lets you transmit quantum (i.e., extraordinarily detailed) information about particles and conceivably a large-scale assemblage of particles (e.g., Captain Kirk) to a remote location. However, detailed information may be unnecessary — and if sci-fi teleportation is to be feasible, it damn well better be.
The problem, familiar to any ‘Net geek, is bandwidth. Physicist Samuel L. Braunstein points out that a fairly coarse scan of the human body (one atomic length in each direction) would require 10³² bits of data. Using today’s best fiber-optic technology, this would take a hundred million centuries to transmit. Even allowing for technological progress, it’s going to be a long time before teleportation as a mode of transportation compares favorably with such none-too-challenging benchmarks as the U.S. mail.
Even if we get over the bandwidth hurdle, consider this. Suppose we could actually sci-fi-TP you somewhere. Even sci-fi writers figure this would entail disintegrating the original and re-creating it elsewhere. The result would be someone who believes she is, and to all appearances would be, you. But is she you — or a copy?
Send questions to Cecil via firstname.lastname@example.org.