In red sweater, tan slacks, and off-white walking shoes, goateed Yakir Aharonov does not immediately stand out as he strides down the colorful streets of Berkeley, California. The town--which proudly proclaims itself THE PEOPLE’S REPUBLIC OF BERKELEY on innumerable tie-dyed T-shirts-- has an almost studied casualness, and Aharonov fits right in. Stopping to relight his momentarily neglected cigar, Aharonov accidentally drops it, then stares for several seconds, apparently considering the propriety of retrieving the smoldering butt from the street.
Ultimately--if reluctantly--Aharonov abandons the stogie, lights a fresh one, and moves on, eager to resume his description of his recent work. It is work of an odd sort, even for a quantum mechanical theorist: Aharonov has designed a time machine. Now I’ve really captured people’s attention, the 59-year-old researcher says, beaming.
Since the era of H. G. Wells, science fiction buffs have gone gaga over the idea of traveling through time. All at once, however, they’ve acquired some serious company. Aharonov--a sober, mainstream physicist who is not only a visiting professor at the University of California at Berkeley but also a faculty member at the University of Tel Aviv and the University of South Carolina--is no less than the third prominent researcher to devote a chunk of his career to studying the realities of time travel.
The process began a few years back when Caltech physicist Kip Thorne, famous for his pioneering theories of black holes, and then graduate student Michael Morris came up with a scheme, based on Einstein’s general theory of relativity, for converting a cosmic wormhole into a time machine (see Discover, June 1989). Cosmic wormholes are theoretical tunnels through space that can directly connect two vastly distant locations--and according to Thorne and Morris’s calculations, two points in time as well. Unfortunately wormholes would also serve as cosmic trash compactors, brutally crushing anything unlucky enough to enter.
The two newer time machines, one proposed by Aharonov and the other by Princeton physicist J. Richard Gott, also rely on Einsteinian relativity to provide the necessary distortion of space and time, but both are more accommodating to the physical comfort of their operators. Plans for the two schemes aren’t exactly at the financing stage--in fact, chances are pretty good neither will ever be realized--but the theoretical workability of the basic ideas has physicists buzzing. This whole thing, says Gott, is telling us a lot about some fundamental areas of physics that have never really been explored. Both of the proposed time travel methods also rely on some pretty extreme science. Aharonov’s, which is probably the more plausible of the two, arose from his studies of one of physics’ most intriguing subspecialties: quantum mechanics.
