Word: quantum
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...have to go to a theater to see these apparitions. In fact, you can't. Quantum Project, a 32-min. epic about a physicist (perpetual star-of-the-future Stephen Dorff) who defies his Merlinish dad (blustery John Cleese) to find love with the proper electron (petrochemical-sunset-haired Fay Masterson), is the first medium-length, Hollywood-style movie made uniquely for the Internet. Just log on to sightsound.com as the Web faithful did at 12:01 a.m., Friday, when Quantum popped online. Pay $3.95 to rent or $5.95 to buy. Download for four minutes--or many hours...
Some argue conservatively that time travelers don't change the past; they were always part of it. On the other hand, paradoxical though this sounds, a version of the many-worlds theory of quantum mechanics (see "Will We Discover Another Universe?" in this issue) devised by Oxford physicist David Deutsch might allow such history-changing visits. In this picture, there are many interlacing world histories, so that if you went back in time and killed your grandmother when she was a young girl, this would simply cause space-time to branch off into a new parallel universe that doesn...
Stephen Hawking has addressed the problem in a different way, proposing what he calls a chronology-protection conjecture. Somehow, he argues, the laws of physics must always conspire to prevent travel into the past. He believes that quantum effects, coupled with other constraints, will always step in to prevent time machines. The jury is still out on this question. We may need to develop a theory of quantum gravity to learn whether Hawking is right...
...will we time-travel in the next century? Travel to the future--yes, but only in short hops, I suspect. To the past--very likely not. Such travel is expensive, dangerous and subject to quantum effects that may or may not spoil your chances of coming back alive. Those of us working in this field aren't rushing to the patent office with time-machine blueprints. But we are interested in knowing whether time machines are possible, even in principle, because answering that question will tell us where the boundaries of physics lie and provide clues to how the universe...
...condensate is a modest thing--measuring about one-tenth of a millimeter across--but the little cloud could help science take big steps. Particles frozen so rigidly in place are easy to observe and manipulate, providing a clearer than ever look at how things behave at the subatomic, or quantum, state. Down the line, such precise control may make it easier to design better atomic clocks or fabricate submicroscopic nanocomponents and other vanishingly tiny machines. Absolute zero might be an impossibility, but for scientists who have spent their careers trying to drive the thermometer down, the deep freeze they...