Dublin sociology student Shane Fitzgerald had the same theory about Wikipedia that many of us have: You can't trust it. So he set out to prove just how untrustworthy it is.

Immediately after hearing the breaking news of the death of film composer Maurice Jarre on March 28, Fitzgerald flew to Wikipedia, the free online encyclopedia in which facts are tended by whomever uses the site. Fitzgerald wasn't interested in vandalizing the Jarre biography page with outrageous information and lies. That would be too obvious. Instead, he invented a quote that sounded like Jarre might have said it:

"One could say my life itself has been one long soundtrack," read Fitzgerald's bogus Jarre quote. "Music was my life, music brought me to life, and music is how I will be remembered long after I leave this life. When I die there will be a final waltz playing in my head that only I can hear."

Wikipedia's administrators eventually realized the quote had improper attribution and got rid of it, but not soon enough to keep it out of newspapers around the planet. Major newspapers and blogs in the United States, Britain, and India used the quote in their obituaries of Jarre. When Fitzgerald finally spoke up and exposed the journalists for the lazy hacks they were, most of the publications quietly removed the quotes from their online versions. Only one -- Britain's The Guardian -- issued a public correction.

Fitzgerald's experiment has so many troubling connotations that it would take an entire book to discuss them. As a journalist, I am especially disturbed by the speed at which rumors fly, unchecked, through the media. Part of the blame falls to corporate media ownership, which forces staff to pump out so many stories that high standards are abandoned. Part of the blame falls to the impatience of our culture, as blogs and TV channels race to be get the story first and get it correct second. And part of the blame falls on us, the people whose insistence on favoring free news outlets only encourages the perpetuation of underfunded, under-researched stories. When a journalist is working at speed and under pressure, these things happen. They always have, and they always will.

It happens far more often than you would think. Last week, I covered some rumors about American Idol contestant Danny Gokey that were circulating around the web. Several websites had reported the rumor, which accused Gokey of being a secret spokesman for LensCrafters, and I linked to many of them in my original story. But I did something additional. I did what I was trained to do and what I believe is the right thing to do: I contacted LensCrafters' corporate offices directly to see if the rumors were true.

LensCrafters told me that I was the only journalist to have bothered to ask. All those rumors flying around, so many readers in an uproar about the story in so many outlets -- and no one before me had spent five minutes to call and see if it was true.

Many people are turning to the web for their information because it's usually free there. Students are cribbing papers from Wikipedia, mothers are getting medical advice from the peanut gallery at Yahoo Answers, researchers are plugging holes in their knowledge with web searches rather than through reliable, fact-checked sources, and even the TV news channels are turning to gossip blogs for story ideas. This very blog is free. But all this free information can come at a price: accuracy.

If I'm reporting what another blog said, and that blog got the story from a third blog, who's checking to make sure the very first source got things correct? If you're using the web for your news, you should always check on where your source got its information. That goes double for Wikipedia. If those obituary writers had taken that step, the quote wouldn't have made it into print in the first place.

Sources for properly researched information are not always easy to find because readers can't know the journalistic standards of the publication they're reading. Legitimate, properly researched sources are fading away, too: Wikipedia's dominance has already precipitated the conquest of Microsoft's digital encyclopedia, Encarta.

"A lie can travel halfway round the world while the truth is putting on its shoes," said Mark Twain. Or did he? If you look around the web, even the attribution Twain quote is in doubt. One website says it actually came from an English Baptist preacher. Twain would have at least loved that irony.