Imagine if the US Department of Justice suddenly announced that it was going to investigate whether America faked the moon landing of 1969; if FBI agents set about examining every theory to find out whether Neil Armstrong really did take that giant leap for mankind; if representatives of President Bush gave their blessing to the investigation, on the grounds that "the truth must be told'.
The equivalent of this wild scenario has just happened here in Britain, with the announcement of an official investigation into whether Princess Diana's death in a car crash in Paris in 1997 was the result of something more than a "straightforward road traffic accident."
Last week, Royal Coroner Michael Burgess opened an inquest and immediately appointed London police chief John Stevens to "thoroughly examine all matters," including, according to one report, "suggestions that the Mercedes was tampered with before the crash or somehow forced off the road."
This is a spectacular waste of public money and police time. The facts of Diana's death speak for themselves - she was being driven through central Paris at high speed by a drunken driver; the three occupants of the car who failed to fasten their seat belts (Diana, her boyfriend Dodi Fayed, and their driver Henri Paul) died when the car hit a tunnel wall; the one occupant of the car who did buckle up (Diana's bodyguard Trevor Rees-Jones) survived.
The French have already spent years on an exhaustive inquiry into the crash, including taking apart the wrecked Mercedes, and concluded in a 6,000-page report that Diana's death was the result of a tragic accident caused by reckless driving.
So why are the British now set to dredge up the old rumors in an inquiry that could last years? This Diana-fest highlights the rising popularity of the conspiracy theory. In our antipolitical age, we are forever on the lookout for the "cover-up" or behind-doors scandal; the knee-jerk response is always to assume that everything the authorities say is an untruth probably concealing a dastardly plot.
Now it seems the British authorities themselves are playing this conspiracy game by investigating whether one of their number really did have a hand in Diana's death.
There have long been lunatic claims about how Diana died. An estimated 36,000 Diana conspiracy websites pore over stories that Henri Paul was injected with substances to make him drowsy; that a mysterious figure flashed a light to cause the car to crash; that the security cameras in the tunnel had been turned to face the walls on the night Diana died.
Such claims could only seem convincing to the crankiest of conspiracy theorists. We are expected to believe that someone somehow knew exactly what time Diana would leave the Ritz hotel, exactly what route her car would take, that she wouldn't bother putting a seat belt on, and then did something to cause her car to crash - all without being spotted by any of the good citizens of Paris.
Now such theories have gone mainstream, triggered by the recent revelation that Diana wrote a note before she died, speculating that someone (Prince Charles, apparently) was "planning an accident in my car." Many overlook the fact that when she wrote that note, having just suffered the double whammy of divorce and the loss of the title Her Royal Highness, Diana was feeling, in the words of one account, "paranoid and cornered."
It is not new facts or evidence that is driving the mainstreaming of the Diana conspiracy-mongering. Rather, many of Diana's admirers seem incapable of believing that she died in an unnecessary, reckless, and tragic accident. They want desperately to give her death some meaning by imagining that it was part of some grand conspiracy, that Diana was the victim of a heartless dynasty that wanted her out of the picture. The truth, however, is far more mundane: Her death was meaningless; it was an accident.
The car-crash conspiracies also chime perfectly with our cynical climate. Diana's recently revealed note and the willingness of the royal coroner to reexamine the circumstances surrounding her death have provided a pretext for an outpouring of conspiratorial speculation and cynicism about authority, which increasingly pass for public debate.
Today, in the absence of wider political beliefs and convictions, many simply distrust the powers that be. Rather than challenging them or offering an alternative, we constantly speculate about what they do in secret, away from the public's gaze. In Britain, Diana has become a symbol of people's dislocation from political and public life; in death, she has become the woman through whom we express our frustration and dissatisfaction with the authorities.
It's time we grew up: Man did land on the moon, and Diana died as the result of an accident.
• Brendan O'Neill is assistant editor of spiked-online.com.