Faster than a speeding gluon, more powerful than a nuclear blast, able to crunch data in colossal bursts? It's the ultimate laptop, envisioned by Seth Lloyd of the Massachusetts Institute of Technology, and it stretches the laws of physics to their limits.
"Computers are physical systems," Lloyd contends. "The laws of physics dictate what they can and cannot do." Lloyd invokes a combination of relativity theory, quantum mechanics, and the laws of thermodynamics to elucidate these outer limits. He describes the result—his hypothetical ultracomputer—in the Aug. 31 Nature.
For the last 4 decades, steady improvements in manufacturing technology have allowed circuitry to be packed ever more tightly onto silicon chips, doubling computer power every 18 months or so. Lloyd decided to find out what the fundamental constants of nature—the speed of light, Planck's constant, and the gravitational constant—have to say about how far miniaturization ca