So, apparently it was Oswald after all.

In preparation for the 45th anniversary of the assassination of John F. Kennedy, the Discovery Channel assembled a team of experts to re-investigate the shooting. According to its program that aired last night, modern technologies like blood-splatter analysis and computer modeling show that the shots came from the sixth floor of the Texas School Book Depository Building. The grassy knoll has been ruled out.

Don't expect this to convince too many people. Scientifically speaking, the case has been closed for decades. There are plenty of fishy things about Oswald and the CIA, but all the evidence points toward a lone gunman. Despite this, polls consistently show that most Americans believe in a "second shooter."

Conspiracy theories are seductive. When I was a sophomore in high school, I started a Web site to explain how the Apollo 11 moon landing was faked in a Hollywood studio by Stanley Kubrick. I found lots of photos where the shadows looked funny, a few where the crosshairs were missing or at strange angles, and even a video that made it look like the American flag was waving in the supposedly windless atmosphere.

This was back in the day when it was easy to manipulate search-engine rankings, and I started promoting my Web site just before FOX aired a prime-time "documentary" making the same claims that I was. My site was quickly overwhelmed with visitors, including some scientists and photographers. It didn't take long before they proved that everything I'd written was completely wrong. I took my site down, but there are dozens of them still out there, publishing the same inaccurate information that I used to.

Moon landing conspiracy theories aren't as popular now as they used to be, but the equally ridiculous 9/11 hoax theories are.

We've all seen the YouTube videos - "Loose Change," "911: In Plane Site," "Zeitgeist" and countless others. Just the fact that these videos exist seems like a strike against the conspiracy theories. If the government is willing and able to secretly murder thousands of people in the most unnecessarily complicated plot in human history, silencing a few guys editing together clips in their basement should be pretty simple.

The most frustrating thing about the 9/11 Truth Movement is how easy it is to debunk its "evidence." About once every week or two, I'll see a posted item show up in my Facebook News Feed that asks, "Why are there no photos of airplane debris outside the Pentagon?" or tells me, "The planes that hit the Twin Towers were not commercial jets!" It literally takes 5 seconds to do a Google Images search and disprove these claims, but people keep falling for them anyway.

There is not a single demolitions or structural-engineering expert anywhere in the entire universe who says the World Trade Center could not have been destroyed by the result of the plane impacts. There is a small handful of scientists who buy into the theory that the towers were brought down by the government, but none of them actually work in any relevant fields.

Let me repeat this for emphasis. Absolutely nobody who studies explosives or how buildings are engineered for a living thinks that there was anything fishy about the collapse of the Twin Towers or World Trade Center Tower 7.

You can divide believers of false conspiracy theories into two groups. The first group is the largest one. It's made up of people who saw part of an Internet video or read an article and didn't have time to do any fact-checking. They believe simply because they got some bad information.

The second group is made up of people suffering from "true-believer syndrome." The term was coined by M. Lamar Keene in his book "The Psychic Mafia" to describe people who continued to believe that a fake psychic named Raoul was genuinely supernatural, even after Raoul admitted to them that he was a fake and showed them how he did his tricks.

No matter how many of their claims you debunk, True Believers are just going to pore over more grainy footage, looking for anything that they can twist to fit their preconceived ideas. They're the ones who will collect photos of WTC 7, delete the ones of the south side of the building that show extensive fire damage, and then put the rest in a YouTube video and tell you that there was no fire damage.

That's not to say that all conspiracy theories are unfounded, and I'm glad that we live in a society where people question and investigate everything. But if a significant segment of the voting populace thinks that science is a hoax and that the world is secretly run by a cabal of international bankers from Israel, we're in trouble.

Adam Roberts is a columnist for The Arkansas Traveler. His column appears every Monday.

http://media.www.thetraveleronline.com/media/storage/paper688/news/2008/11/17/Opinion/The-Truth.About.911-3546528.shtml