At a moment when the world's need for information has never been greater, the Internet's role as the ultimate source of unmediated news has been matched only by its notorious ability to breed rumors, conspiracy theories and urban legends.

If you have an e-mail account, you are almost certainly familiar by now with the 1654 quotation from Nostradamus "predicting" the attack on the World Trade Center, which has been circulating and recirculating since the Sept. 11 terrorist attacks.

You have surely seen the face of Satan in the pictures of the smoke rising from the decimated twin towers. You may even have stepped outside with a lighted candle at 10:30 p.m. one night last week in response to e-mail stating that NASA planned to take a satellite picture as a memorial to the attack victims. "Please pass this on to as many people as possible," read the message (which turned out to be bogus).

The Internet has a long tradition of incubating rumors. E-mail hoaxes have promised that the first 13,000 people to forward a message would win cash or trips to Disneyworld; sworn that the author Kurt Vonnegut advised new graduates to "wear sunscreen" during a commencement speech he never gave; and recounted the false story of a woman forced to pay $250 for the Neiman Marcus chocolate chip cookie recipe.

But it may be a measure of just how much stranger truth has come to seem than fiction that many Internet users — including a number of normally cynical New Yorkers — are having more difficulty telling online rumor from reality.

Did Clear Channel Communications officially ban its American radio stations from playing a long list of potentially offensive songs including "Burning Down the House" by the Talking Heads and the Beatles' "Ticket to Ride"? Not exactly — it was a suggestion — but the question was hotly debated on dozens of sober-minded Internet discussion groups where the list was posted.

Did an Afghan-American author named Tamim Ansary write an essay decrying the notion of "bombing Afghanistan back to the Stone Age" because "it's already been done?" Yes, but the article — which Mr. Ansary e-mailed to a few friends — appeared in so many inboxes that some recipients thought it was a hoax. (SkFriends note Sep 23, 2001 - Confirmed true: Bomb Afghanistan and Bin Laden Wins)

In a sign of the hunger to explain the inexplicable, "Nostradamus" has joined "sex" and "mp3" on the list of terms most frequently entered on Internet search engines, as people scramble to learn more about the French astrologer who wrote that "the third big war will begin when the big city is burning" after "two brothers" are "torn apart by Chaos." Others are stampeding to sites like www.snopes2.com, which rates current rumors green, red and yellow depending on whether they are deemed to be true, false or undetermined.

Still, the incessant blending of fact and fantasy on the Web looks a lot like a venerable response to tragedy in a slightly new form, according to people who have studied the origin of rumors and urban legends. The need to arrive at a common understanding of a disaster — and to forge a united front to deal with it — often leads to an outpouring of theories that may or may not be true.

Indeed, conspiracy theorists did just fine without the Internet in the decades following the assassination of John F. Kennedy. The difference with the Internet is that the rumors are more plentiful and mutate much more quickly in a global game of telephone.

"When somebody thinks they have a piece of information in a disaster they want to tell everyone they know to bring everyone into a consensual reality," said Camille Bacon-Smith, editor of the online journal New Directions in Folklore. "They want to bring everyone into the group, and with the Internet the group is huge."

Sometimes the swirling bits of misinformation can be exasperating. But sometimes they may simply express a collective sense of hope. Did a man trapped on the 82nd or 71st or 100th floor of the collapsing World Trade Center ride the falling debris to safety? Probably not, according to snopes2.com, where the rumor is coded yellow, "but at this point in time, it's still not known."

Here are some recent rumors culled from e-mail lists and Web sites. Answer true or false to test your grip on reality.

1. A body with bound hands was found atop one of the buildings near the former World Trade Center towers.

2. CNN used old footage of Palestinians dancing in the street after the terrorist attack.

3. The television evangelist Jerry Falwell said civil liberties groups, feminists, homosexuals and abortion rights supporters bear partial responsibility for the attacks because their actions have turned God's anger against America.

4. Following the attacks, a prominent Canadian broadcaster declared that "it is time to speak up for the Americans as the most generous and possibly the least- appreciated people on all the earth."

5. The number 11 comes up a lot. For instance, the attack was on 9/11, and 9+1+1=11. Also, New York City, Afghanistan and the Pentagon each has 11 letters. The twin towers, standing side by side, looked like the number 11. And so on.

6. The planned cover for a hip-hop album due to be released in November depicted an exploding World Trade Center.

7. Typing NYC into a Microsoft Word document, highlighting it and changing the font to Webdings reveals a positive message.

1. True. 2. False. 3. True (Falwell later retracted the statement). 4. Mostly false (Gordon Sinclair's defense of America was delivered in 1973). 5. True, perhaps. 6. True. 7. True: NYC =