# Prime suspect

By Charles Seife THE search for the world’s largest prime number might lead to a jail term. A Colorado man is now under investigation for allegedly hijacking a phone company’s computers to enlist their aid in finding a record-breaking prime. Prime numbers—those that can’t be divided evenly by any whole number other than 1 and themselves—are the atoms of the mathematical world. Just as all molecules are made up of atoms, all numbers are the product of prime numbers. Though there are an infinite number of primes, big ones are tough to find. So for many years, mathematicians have been vying with each other to find larger and larger prime numbers. Since November 1996, the world records has been held by the Great Internet Mersenne Prime Search (GIMPS)—a ragtag bunch of number-lovers who have devoted their computers’ spare time to looking for ever larger primes. Their combined computing power is 200 gigaflops—roughly equivalent to seven top-of-the-range supercomputers. Thanks to that awesome power, GIMPS has found three record-breaking primes so far. The biggest is more than 900 000 digits long. Aaron Blosser, a computer expert who worked as a contractor for US West, a telecommunications company based in Denver, Colorado, gave its vast network of computer workstations the task of searching for even larger primes. The program he unleashed onto the company’s network should have only done its calculations when the computers’ processors were idle. But US West claims that things didn’t work out that way. Company spokesman David Beigie says the program disrupted US West’s directory information service. “The computers need to look up databases,” he says. “Instead of taking fifteen seconds, a request took more like a minute.” Beigie says the problem was tracked down to the prime-hunting software installed by Blosser. He didn’t ask permission from the people who oversee the security of US West’s computer network before he installed the program. Blosser’s attempts to convince US West’s network managers that the program posed no security risk to the company have fallen on deaf ears. His home has been searched by the FBI and his computer equipment has been confiscated. Though Blosser has not yet been charged, Beigie says: “We are recommending that he be prosecuted to the full extent of the law.” Blosser protests his innocence. “I didn’t hack in or anything,” he claims. “I used my own name and password.” “US West is overreacting,” says George Woltman, a retired computer programmer in Orlando, Florida, who leads GIMPS and wrote the prime-hunting software. “It wasn’t a malicious thing. He wasn’t trying to do any damage.” Though Blosser managed to use more than 2500 computers to do an enormous amount of computing in a short period of time, he didn’t find a monster prime. “It takes a few weeks before you get a result,