A date for all people.

Cesare Emiliani has a few complaints about the Gregorian calendar used by much of the world. The split between B.C. and A.D., he says, confuses arithmetic computations because there is no zero year. While time moves in only one direction, year numbers grow larger going both forward and backward in time. What's more, the calendar defines time relative to an event that holds little meaning for non-Christians, who make up more than half the world's population, according to Emiliani, a geoscientist at the International Academy of Sciences in Palm Beach Gardens, Fla.

As a solution, he suggests pushing back the starting date of the calendar 10,000 years, making the current year 11,995. Such a revision would have the beginning of the calendar coincide with the start of the current geologic time period, the Holocene epoch. This time has important worldwide significance because it marks the end of the last ice age and the beginning of agriculture, says Emiliani, who organized a session of historians and scientists to discuss the idea.

The resetting requires only simple arithmetic: add 10,000 to all A.D. years and subtract all B.C. years from 10,001. After the turn of the century, people could adopt a shortcut by replacing the number 12,000 with an apostrophe. The year A.D. 2001 would then become '1.

Has the time arrived for calendar reform?

"There are great advantages for certain people, but there are no advantages for others," admits Emiliani, who has been pursuing the idea for several years.