Why 9/11 was a conspiracy

This led to an increased buildup of stress in the sagging floors, until the floor framing and connections gave in. The collapsing floors then fell on more floors below, leading to a progressive collapse.

It is understood the South Tower collapsed sooner because it suffered more damage from the initial aircraft impact, which also dislodged more fireproofing material. While there are different theories regarding how the progressive collapse of Building 7 was initiated, there is consensus among investigators fire was the primary cause of failure. Both official reports made a range of fire safety recommendations for other high-rise buildings, including to improve evacuation and emergency response.

In , the National Institute of Standards and Technology also published a best practice guide recommending solutions to reduce risk of progressive collapse. There have since been changes to building codes and standards on improving the structural performance of buildings on fire, as well as opportunities to escape such as added stairwell requirements.

At the same time, the collapse of the twin towers demonstrated the very real dangers of fire in high-rise buildings. In the decades since the World Trade Center was designed, buildings have become taller and more complex, as societies demand sustainable and cost-effective housing in large cities.

Repeated surveys show a small percentage of Americans continue to harbor doubts about the official explanation of the attacks.

Shocking, sudden events often spawn conspiracy theories as people collectively grapple with understanding them, says Mark Fenster, a University of Florida law school professor who has studied the history of conspiracy theories in America. That runs into the Pentagon? Before the internet, conspiracy theorists relied on books, pamphlets and the occasional late night television show to espouse their beliefs.

Now, they can swap theories on message boards like Reddit, post videos on YouTube, and win over new converts on Facebook, Twitter or Instagram. Thousands of videos focus on conspiracy theories. False claims about the attacks often come up at the National Sept. This is an opinion and analysis article; the views expressed by the author or authors are not necessarily those of Scientific American.

Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Discover World-Changing Science. But according to an official report, the crashed planes considerably damaged support columns of both the towers and dislodged fire-proofing. Additionally, the fires reached up to 1,C in some areas, causing the steel beams to warp and the eventual collapse of the buildings.

This building - containing offices of the CIA, the Department of Defense, and the Office of Emergency Management - collapsed hours after the Twin Towers without being hit by a plane or directly targeted. But in , a three-year investigation by the National Institute of Standards and Technology concluded it had collapsed because of intense and uncontrolled fires - lasting for nearly seven hours - started by debris from the fall of the nearby North Tower.

But in , the Plasco tower in the Iranian capital, Tehran, became the second. The fact the collapse of 7 World Trade Center was announced in a live report by BBC News correspondent Jane Stanley - while it was still visibly standing behind her - has been cited by conspiracy theorists as evidence major media organisations were part of the inside-job plot. The Reuters news agency had mistakenly reported the collapse of the building, which was also picked up by CNN, just before the live report.

Some online conspiracy theories suggest US missiles were fired at the Pentagon, as part of a government plot, and the hole left in the building was too small to have been caused by a passenger plane. But a member of the American Society of Civil Engineers told Popular Mechanics magazine the size and shape of the hole was due to one wing of the Boeing hitting the ground and the other being severed on impact with the building.