Every year, around the anniversary of the toppling of New York's iconic Twin Towers in 2001, a raft of stories pops up like mushrooms, detailing all the reasons you shouldn't believe that terrorists were behind 9/11.
As we approach the 16th anniversary of that terrible day, here's why all those stories really are just like mushrooms: they're founded in bullsh*t.
CLAIM: Burning jet fuel cannot physically melt steel beams
It's true that jet fuel has a top burn temperature of between 427-815 degrees Celcius, and that steel's melting point is at a much hotter 1510 degrees Celcius. However, this misses the point that steel's structural integrity is compromised much sooner. On 9/11 the support beams of the towers didn't need to melt – they just needed to soften enough to bend.
"I have never seen melted steel in a building fire," retired New York deputy fire chief Vincent Dunn, author of The Collapse Of Burning Buildings: A Guide To Fireground Safety, told Popular Mechanics. "But I've seen a lot of twisted, warped, bent and sagging steel. What happens is that the steel tries to expand at both ends, but when it can no longer expand, it sags and the surrounding concrete cracks."
CLAIM: Puffs of dust escaping the buildings show it was a controlled detonation
Conspiracy theorists have had a field day over this one, with one advertisement for the book Painful Questions: An Analysis Of The September 11th Attack claiming that, "The concrete clouds shooting out of the buildings are not possible from a mere collapse. They do occur from explosions." But, no. This is simply not the case. In fact, as the top floors collapsed from the impact of the jets, their weight landed on each subsequent floor below with pulverising force, which engineers call "pancaking". As the air between each floor was expelled when they connected, dust was pushed out into the surrounding sky.
CLAIM: They weren't planes that hit the towers – they were missiles.
This one is simply too bizarre to understand. Fuelled by one early eyewitness who thought the first plane had no windows, this theory is easily debunked by anyone who's seen some of the ample video and photographic documentation of the event. Those were, tragically, commercial jets.