That's right, these people put their reputations in potential jeopardy because they don't buy the government's version of events. They want to know how 200,000 tons of steel disintegrated and fell to the ground in 11 seconds. They question whether the hijacked planes were responsible – or whether it could have been a controlled demolition from inside that brought down the twin towers and Building 7.

Richard Gage, a member of the American Institute of Architects and the founder of Architects and Engineers for 9/11 Truth, put it like this: "The official Federal Emergency Management [Agency] and National Institute of Standards and Technology reports provide insufficient, contradictory and fraudulent accounts of the circumstances of the towers' destruction." He's especially disturbed by Building 7, whose 47 stories came down in "pure free-fall acceleration" that afternoon – even though it was never hit by an aircraft.

This is a subject I take up in my new book, American Conspiracies, published this week by Skyhorse. An excerpt follows:

Some people have argued that the twin towers went down, within a half hour of one another, because of the way they were constructed. Well, those 425,000 cubic yards of concrete and 200,000 tons of steel were designed to hold up against a Boeing 707, the largest plane built at the time the towers were completed in 1973. Analysis had shown that a 707 traveling at 600 miles an hour (and those had four engines) would not cause major damage. The twin-engine Boeing 757s that hit on 9/11 were going 440 and 550 miles an hour.

Still, we are told that a molten, highly intense fuel mixture from the planes brought down these two steel-framed skyscrapers. Keep in mind that no other such skyscraper in history had ever been known to collapse completely due to fire damage. So could it actually have been the result of a controlled demolition from inside the buildings? I don't claim expertise about this, but I did work four years as part of the Navy's underwater demolition teams, where we were trained to blow things to hell and high water. And my staff talked at some length with a prominent physicist, Steven E. Jones, who says that a "gravity driven collapse" without demolition charges defies the laws of physics. These buildings fell, at nearly the rate of free-fall, straight down into their own footprint, in approximately ten seconds. An object dropped from the roof of the 110-story-tall towers would reach the ground in about 9.2 seconds. Then there's the fact that steel beams that weighed as much as 200,000 pounds got tossed laterally as far as 500 feet.

The National Institute of Standards and Technology (NIST) started its investigation on August 21, 2002. When their 10,000-page-long report came out three years later, the spokesman said there was no evidence to suggest a controlled demolition. But Steven E. Jones also says that molten metal found underground weeks later is proof that jet fuel couldn't have been all that was responsible. I visited the site about three weeks after 9/11, with Governor Pataki and my wife Terry. It didn't mean anything to me at the time, but they had to suspend digging that day because they were running into heat pockets of huge temperatures. These fires kept burning for more than three months, the longest-burning structure blaze ever. And this was all due to jet fuel? We're talking molten metal more than 2,000 degrees Fahrenheit.

Probably the most conclusive evidence about a controlled demolition is a research paper (two years, nine authors) published in the peer-reviewed Open Chemical Physics Journal, in April 2009. In studying dust samples from the site, these scientists found chips of nano-thermite, which is a high-tech incendiary/explosive. Here's what the paper's lead author, Dr. Niels Harrit of the University of Copenhagen's chemistry department, had to say about the explosive that he's convinced brought down the Twin Towers and the nearby Building 7:

"Thermite itself dates back to 1893. It is a mixture of aluminum and rust-powder, which react to create intense heat. The reaction produces iron, heated to 2500 degrees Centigrade. This can be used to do welding. It can also be used to melt other iron. So in nano-thermite, this powder from 1893 is reduced to tiny particles, perfectly mixed. When these react, the intense heat develops much more quickly. Nano-thermite can be mixed with additives to give off intense heat, or serve as a very effective explosive. It contains more energy than dynamite, and can be used as rocket fuel."

Richard Gage is one of hundreds of credentialed architects and structural engineers who have put their careers on the line to point out the detailed anomalies and many implications of controlled demolition in the building collapses. As he puts it bluntly: "Once you get to the science, it's indisputable."

Read also: New York to Pay Up to $657Million to World Trade Center Responders

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