This is not a good day for paraskevidekatriaphobics -- those who fear Friday the 13th. It's double-13 Friday. All the numbers in the numerical notation -- 10/13/2006 -- add up to 13 as well, giving great pause to the superstitious.
The phenomenon hasn't happened in 476 years, said Heinrich Hemme, a physicist at Germany's University of Aachen who crunched the numbers to find that the double-whammy last occurred Jan. 13, 1520.
"Pure chance," the good professor told the press yesterday.
But it's not exactly TGIF for the 21 million Americans who fear the day. Some may not travel or even get out of bed, said Donald Dossey, a North Carolina psychologist who coined the term "paraskevidekatriaphobia" 20 years ago. He estimates that the nation is out $900 million in lost productivity because of Friday the 13th sick-outs.
"It's just ingrained in our culture -- one of those collective, unconscious fears stretching back about 2,800 years," Mr. Dossey said. "But it will be all gone tomorrow. By the time you learn to pronounce 'paraskevidekatriaphobia,' you're cured."
Friday the 13th has had unlucky baggage for centuries, with references to "bad" Fridays cited in the Bible, Norse mythology, Chaucer, French and British history, numerology and folklore sources, Mr. Dossey said.
Presidential hopeful John Edwards must be phobia-free. The former Democratic senator from North Carolina begins his 13th campaign trip to Iowa today, according to the Des Moines Register.
Some folks are stuck with the date. Among those born on a Friday the 13th are Thomas Jefferson, Fidel Castro, actors Julia Louis-Dreyfus and Don Adams, philanthropist Walter Annenberg, ex-Monkee Peter Tork and former first lady Bess Truman. Benny Goodman, Hubert Humphrey and rapper Tupac Shakur were among those who died on the day.
Pollsters have not ignored it: A 1990 Gallup poll revealed that 9 percent of Americans fear the day, while an American Demographics survey placed the percentage at about 13 percent.
British psychologist Richard Wiseman may be more attuned to Friday the 13th than anyone. His landmark survey of 4,000 adults in 2003 found that a quarter of them said the number 13 was unlucky, 64 percent crossed their fingers for luck and 49 percent refused to walk under ladders.
And today's heebie-jeebies? Mr. Wiseman says that those who get anxious about it actually increase their chance of accident or argument. He also thinks some people "want to be unlucky" because it allows them to shirk responsibility for their mistakes, according to the British Broadcasting Corp.
Friday the 13th is always ideal for a scary movie debut or book release. The horror sequel "The Grudge 2" opens nationally today.
Philadelphia's "Haunted Express" bus tour of the city's eerie spots will ask riders to walk under a ladder, break a mirror, step on a sidewalk crack and confront a black cat before embarking tonight, spokeswoman Leslie Bari said.
"Guests will have the opportunity to challenge superstition," she said.