9/11 conspiracy theories: The truth is out there...just not on the internet

In his new book a Times commentator debunks the world's greatest conspiracy theories. Here he deconstructs those that followed 9/11 and the 7/7 bombings

The internet has created shadow armies whose size and power are unknowable. Cyberspace communities of semi- anonymous and occasionally self-invented individuals have grown up, some of them permitting contact between people who in previous times might have thought each other's interests impossibly exotic or even mad. At the same time, the democratic quality of the net has permitted the release of a mass of undifferentiated information, some of it authoritative, some speculative, some absurd. But, increasingly, material originating on the net has turned up in popular culture - a millennial version of the word-of-mouth route to popularity. The online encyclopaedia Wikipedia has, at the time of writing, become a first resource for many students, despite the amusing randomness of its reliability.