Twenty years hence, computing power will be sufficiently embedded in daily life so that the word "computer" may disappear from our language, according to a prominent theoretical physicist. But computers' inability to account for common sense will prevent widespread artificial intelligence.

In his opening keynote address at the 11th annual InformationWeek Fall Conference in Tucson, Ariz., Michio Kaku, a professor of theoretical physics at the City University of New York, painted a vision of technical, corporate, and social changes wrought by scientific advances over the next 20 years. Kaku based his talk on interviews culled for his 1998 book, Visions: How Science Will Revolutionize the 21st Century.

"Some people think the future is going to be cold, impersonal, disembodied," Kaku said. But the persistence of Moore's Law--which predicts that the number of transistors on a microprocessor (and thus computing power at a given price point) will double every 18 months--means we're on the cusp of an era of "ubiquitous computing," he said. Kaku forecast a breakdown in that cycle of advancements, though. By 2020, he said, the cost of a Pentium-powered chip will have dropped to a penny and computers that harness molecular and quantum energy to perform calculations will be on the verge of replacing silicon-based machines.

Could that herald an era of ubiquitous artificial intelligence? Not so fast, cautioned Kaku. According to his research, computers that simulate intelligence spend most of their time processing things humans take for granted. "Where in a line of computer science does it say that mothers are older than daughters?" Kaku pondered. "We can't reproduce the common sense of a five-year-old child."