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--MOLECULAR AND DOT COMPUTERS Other exotic designs include the molecular computer and the quantum dot computer (which replace the silicon transistor with a single molecule and a single electron, respectively). But these approaches face formidable technical problems, such as mass-producing atomic wires and insulators. No viable prototypes yet exist.
--THE QUANTUM COMPUTER The darkest horse to emerge in this race is the quantum computer, sometimes dubbed the ultimate computer. The idea is to direct a laser or radio beam on a carefully arranged collection of atomic nuclei, each of which is spinning like a top. As the beam bounces off the atoms, it flips the spins of some of them. Complex computations can be performed by analyzing how the spins have been flipped.
U.S. Intelligence Agencies are nervously eyeing these new designs. Quantum computers, in particular, could be so powerful that they might one day break the most intricate secret codes the CIA can concoct. Not that a quantum supercomputer is going to leap out of some laboratory and paralyze the CIA anytime soon. These computers seem to be exquisitely sensitive. The tiniest disturbance--even a passing cosmic ray--can change the orientation of their computational atoms, spoiling the calculation. At present, quantum computers can perform only trivial calculations on perhaps five atoms. To do any useful work, they would need to calculate on millions of atoms.
Clearly, none of these designs are ready for prime time. Most are still on the drawing board, and even those with working prototypes are too crude to rival the convenience and efficiency of silicon.
There may be a silver lining to all this. If Moore's law somehow continues unabated, then by some estimates our computers by 2050 will be calculating well beyond 500 trillion bytes per sec., at which point, as Ray Kurzweil suggests (see "Will My PC Be Smarter Than I Am?"), they will be considerably smarter than we are. Evolution says organisms are replaced by species of superior adaptability. When our robots tire of taking orders, they may, if we're lucky, show more compassion to us than we've shown the species we have pushed into oblivion. Perhaps they will put us into zoos, throw peanuts at us and make us dance inside our cages.
Maybe the collapse of Moore's law isn't such a bad thing after all. If none of these exotic designs pan out, our computers won't automatically increase in power every Christmas. But perhaps that's a small price to pay for our freedom.
Michio Kaku is a physics professor at City College of New York and author of Visions: How Science Will Revolutionize the 21st Century