Special 21stC home page  Digital soup: DNA as a computational
device   A SALESMAN PLANS to visit 50 cities. What's the most
efficient route for him to follow? No conventional computer can
calculate the answer without years of computing time. But in
November 1994, Len Adleman at the University of Southern
California unveiled a model for an unconventional computer that
just might lead one day to a solution of the traveling salesman
problem: a test-tube containing one-fiftieth of a teaspoon of
water teeming with DNA.  Biologists and computer scientists had
only daydreamed about DNA computing. But since Adleman's
experiment, the handful of scientists trained in both computer
science and biochemistry have begun to combine these fields of
expertise to make test-tube trials possible. Any practical
device is decades away, but the potential is awesome. A soup of
1018 DNA strands would possess 10,000 times the power of today's
best supercomputers, opening the door to applications like
scheduling mass transit, designing