9/11 conspiracy theories

Soon after the terrorist attacks of 9/11, conspiracy theories began to crop up about how it was an "inside job," planned and executed by the U.S. government.

Here how are some of the more common conspiracy theories and the experts' response.

1. The World Trade Center twin towers were destroyed by planned demolitions.

Experts dispute this on several grounds. Among them, there were none of the telltale signs of a controlled explosion. Other demolition crews in Manhattan have sensitive seismographs and none recorded explosions that morning. Cutting away conduits, plumbing and insulation to plant charges would certainly have been noticed.

2. It wasn't a plane that hit the Pentagon but a missile fired by Americans.

Experts say conspiracy theorists overlook the remains of the bodies of the crew and passengers of American Airlines flight No. 77. Additionally, the plane's black box was recovered from the site.

3. The planes that hit the World Trade Center towers were remotely controlled.

Boeing manufactured the planes that struck the towers and the company states that all of its commercial jets are designed so that they cannot be controlled from anywhere except the flight deck.

4. 4,000 Jews failed to show up for work at the World Trade Center on Sept. 11.

Media reports indicated that 10 to 15 percent of the victims were Jewish, indicating that there were no "mass absences."

The 4,000 figure apparently came from a statement from the Israeli Foreign Ministry stating that's how many Israelis were in the New York and Washington areas when the attacks occurred.