9/11 coverup

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[edit] Definition

The 9/11 coverup deals with the conspiracy theory that the attacks of September 11, 2001 were not terrorist acts but were in fact committed by the US government.

[edit] Discussion

Apparently the real 9/11 conspiracy, in which terrorists conspired to attack the World Trade Center and the Pentagon, is not enough of a conspiracy for some theorists. They make a number of claims about the 9/11 attacks, very few of which stand up to scrutiny.

[edit] The "Official" Story?

9/11 conspiracy theorists often say they're poking holes in the "official" story, which is that terrorists hijacked four planes, flew one into each World Trade tower and one into the Pentagon, and while they flew the fourth toward an unknown target it was taken down by the passengers.

The problem comes in the details. Conspiracy theorists can never seem to agree on the details of what the "official" story says. Some say the "official" story is that the fires in the World Trade Center towers got hot enough to melt the steel, others claim the steel was pulverized or turned to dust. None of these claims appear anywhere in the scientific examination of the attacks or how the towers fell. Therefore, this site will not attempt to make any claims or examinations of whatever "official" story the theorists claim to be debunking; instead, the scientific examination will be used to refute their claims.

[edit] The Collapse of the WTC Towers

The World Trade Center towers
The World Trade Center towers

Not surprisingly, most of the conspiracy claims center around the World Trade Center towers and how they collapsed.

[edit] The Main Towers

One claim that the theorists repeat like a mantra is that no steel structure has ever collapsed because of fire. They claim that the fire alone could not have caused the collapse, and therefore the towers had to be deliberately demolished. Another claim is that the towers were meant to survive the collision of an airplane. Also, the buildings fell straight down, not over to one side. All of this, they say, points to the towers being deliberately demolished with explosives.

[edit] Discussion

There are two aspects at play here. One is that this is a strawman argument: none of the scientific examinations seem to have hit on the fire or the impact as the sole cause of the collapse. The other aspect is that the World Trade Centers were not constructed like any other steel building before them, and few since.

The Madrid Windsor Tower is often cited as an example of a steel structure that survived an intense fire. However, the steel perimeter of the upper floors did collapse. The building (and much of the upper floors) did remain standing, but that is explained by the presence of "technical floors" which strengthened the structure. The Madrid Windsor is a very different design to the towers at the WTC.

Traditionally, steel buildings were built using the well-established method of a grid of girders every 30 feet or so. This makes the building very strong, but the fact that there must be a steel column every 30 feet limits floorspace. One of the big selling points of the World Trade Center was its expansive floor space, which was achieved by moving the support structure to two places: a steel outer skeleton, which provided some vertical support but mostly protected the building from the immense winds that skyscrapers encounter, and an inner core of steel girders which provided the main support, which was also where the elevator shafts and stairwells were placed.

These were connected by floor trusses which braced the outer skeleton against the core. This was important because neither the central core nor the outer skeleton could hold up the building on its own.

The towers were fireproofed, but there were two problems. The first was the fact that the use of asbestos had been discontinued, and the second was the desire to cut down the amount of weight on the support structure. To this end, a combination of heat-resistant foam and drywall were used to protect against fires.

When the first plane hit the North Tower, the impact not only destroyed much of the outer skeleton and the core, the shockwave also blew away the light-weight foam and drywall, leaving the steel unprotected from the fire. A similar situation happened when the South tower was hit, except that in that case the plane had hit at an angle, missing most of the core but destroying more of the outer skeleton; it still blew away the fireproofing. Survivors from both towers reported having to move bits of foam and pieces of drywall out of the way as they escaped.

The towers had indeed been designed to protect against the biggest airline of its time: a Boeing 707, but the planes that hit them were much larger 757s. They were also practically filled with jet fuel as they were making the long flight from New York to Los Angeles.

The towers actually stood up very well to the impact, even after losing as much as two-thirds of the steel columns, but immediately after survivors reported that they had begun to smell the jet fuel. This burned a very hot fire that the building's designers could not have accounted for, especially with the fireproofing gone.

None of the scientific reports mention anything close to melting or pulverizing of steel as the conspiracy theorists claim. However, steel will lose half of its strength when it reaches 500°C, and this fire was easily burning at close to that temperature. The conspiracy theorists are correct when they say that this alone would not have caused the towers to collapse, but what it did do was weaken the structure and cause residual stresses on the floor trusses. Once they began to give way, the structure could no longer hold the weight. This aspect of the residual stresses and the loss of the floor trusses does not seem to have been addressed at all by the conspiracy theorists, yet the scientific examinations show them to be the direct cause of the collapse.

It's also not entirely true that the buildings fell straight down. The South Tower actually tipped to one side as it fell, as that was the side that had lost most of its structure. The North Tower fell straighter because it lost more of its structure on the core. Even so, the towers falling straight down is no indication of deliberate demolition. The towers were mostly empty and had no lateral load to push them over to one side. The speed at which they collapsed gave them too much inertia to go anywhere except straight down.

[edit] Tower 7

The conspiracy theorists also focus on Tower 7, for two reasons. One is the usual argument from incredulity that, since the building wasn't directly hit, they can't think of why it should have collapsed. The other is a video of Larry Silverstein saying to "pull" the tower, which they say means he ordered the destruction of the tower.

[edit] Discussion

Tower 7 was not hit by any airplane, but the damage to the main towers did cause both structural damage and fires to it. An analysis of the steel from the ruins of the tower shows that the steel had a high content of sulphur, which can happen when steel is misforged. The sulphur, in addition to burning on its own, also lowered the temperature at which the steel would soften and melt.

As for Silverstein's comments, he was relating a conversation he had had with fire officials in determining whether or not to save the tower. He had said that they had "made the decision to pull it." The conspiracy theorists take that comment out of context, and point out that "pull" is used by building demolishers to mean bringing down a building. Regardless of whether or not this is true, Silverstein is not a building demolisher, and he was speaking to firefighters, not building demolishers. When firefighters use the word "pull," they mean to pull out all of the firefighters and equipment and let the fire run its course. Silverstein's later comments clarify that this is exactly what he meant.

For a fuller discussion, see our main article on WTC7.

[edit] The UL Claim

Many conspiracy sites reference a letter from Kevin R. Ryan, purportedly of Underwriters Laboratories (UL), saying that UL had certified the steel in the WTC towers, that it would have taken temperatures of 3000°F to melt the steel, and other arguments used by the conspiracy theorists. It is argued that this is sound evidence from an expert authority.

[edit] Discussion

Merely being affiliated with a company such as UL does not make one immune to becoming a conspiracy theorist. In any event, Ryan was not directly employed by UL; he was an employee of Environmental Health Laboratories, which is not, as he claimed, a division of UL, but merely affiliated with UL (as many companies are). UL released a public statement saying that they do not certify the steel materials for buildings, and that Ryan was fired for making his absurd and inaccurate comments. No credence should be given to anything Ryan said in his letter.

[edit] The Pentagon

The Pentagon
The Pentagon

Conspiracy theorists have a lot to say about the attack on the Pentagon as well. They claim that the hole in the side of the Pentagon was nowhere near the wingspan of a 757. They claim that there is no debris from a 757 from the site of the attack. They claim that witnesses say that there were no windows on the plane that did hit.

[edit] Discussion

Why would the hole need to be the size of the wingspan? The plane, according to reports and the damage examined at the scene, hit the ground just before hitting the building, and the force would have torn off the wings. The hole is actually 90 feet wide, the right size for a 757 fuselage. Saying that it isn't big enough for the wingspan is just a distraction; there's no reason why it should be.

Contrary to the claims of the conspiracy theorists, there are plenty of pictures of debris from the plane which are consistent with a Boeing 757, including the jet engines. Some pictures show parts of the fuselage, which clearly has windows.

There are also numerous witnesses saying that it was a 757, some of whom even recall seeing the markings.

[edit] Links and references

[edit] Pro-conspiracy sites

[edit] Informational sites

[edit] Background on controlled demolitions

  • Implosion World : "The explosive demolition industry’s worldwide source for news and information on building implosions, blowdowns and all other types of structural blasting projects."
  • How Building Implosions Work : from howstuffworks.com

[edit] Video footage

[edit] Scientific Examinations

  • "Why Did the World Trade Center Collapse? Science, Engineering, and Speculation" JOM, 53 (12) (2001), pp. 8-11
  • "An Initial Microstructural Analysis of A36 Steel from WTC Building 7" JOM, 53 (12) (2001), p. 18
  • The Towers Lost and Beyond A collection of essays on the WTC by researchers at the Massachusetts Institute of Technology
  • World Trade Center Human Identification Project
  • Engineering and Organizational Issues Related to the World Trade Center Terrorist Attack
  • Initial Model for Fires in the World Trade Center Towers
  • Federal Building and Fire Safety Investigation of the World Trade Center Disaster
  • Thermal images of Ground Zero
  • "Why Did the World Trade Center Collapse?—Simple Analysis" Journal of Engineering Mechanics, Volume 128, Issue 1, pp. 2-6 (January 2002)
  • "Addendum to "Why Did the World Trade Center Collapse?—Simple Analysis" Journal of Engineering Mechanics, Volume 128, Issue 3, pp. 369-370 (March 2002)
  • "Structural Responses of World Trade Center under Aircraft Attacks" Journal of Engineering Mechanics, Volume 131, Issue 1, pp. 6-15 (January 2005)
  • "Stability of the World Trade Center Twin Towers Structural Frame in Multiple Floor Fires" Journal of Engineering Mechanics, Volume 131, Issue 6, pp. 654-657 (June 2005)
  • "A suggested cause of the fire-induced collapse of the World Trade Towers" Quintiere, J.G.; di Marzo, M.; Becker, R. Fire Safety Journal Oct2002, Vol. 37 Issue 7, p707, 10p.
  • "Impact of the Boeing 767 Aircraft into the World Trade Center" Karim, Mohammed R.; Fatt, Michelle S. Hoo. Journal of Engineering Mechanics Oct2005, Vol. 131 Issue 10, p1066-1072.
  • "Could the world trade center have been modified to prevent its collapse?" Newland, D. E.; Cebon, D. Journal of Engineering Mechanics 2002 Vol. 128 Issue 7, p795-800, 6p.
  • "How did the WTC towers collapse? A new theory" Usmani, A. S.; Chung, Y. C.; Torero, J. L. Fire Safety Journal 2003 Vol. 38, p501-533, 33p.
  • "How the airplane wing cut through the exterior columns of the World Trade Center" Wierzbicki, T.; Teng, X. International Journal of Impact Engineering 2003 Vol. 28, p601-625, 25p
  • "Effect of insulation on the fire behaviour of steel floor trusses" Fire and Materials, 29:4, July/August 2005. pp. 181 - 194. Chang, Jeremy; Buchanan, Andrew H.; Moss, Peter J.
  • "A simple model of the World Trade Center fireball dynamics" Proceedings of the Combustion Institute 30:2, January, 2005. pp. 2247-2254. Baum, Howard R.; Rehm, Ronald G.
  • "Reconnaissance and preliminary assessment of a damaged high-rise building near Ground Zero" The Structural Design of Tall and Special Buildings. 12 :5, 15 December 2003. pp. 371 - 391. Warn, Gordon; Berman, Jeffrey; Whittaker, Andrew; Bruneau, Michel
  • "Structural Responses of World Trade Center under Aircraft Attacks", Omika, Yukihiro.; Fukuzawa, Eiji.; Koshika, Norihide. Journal of Structural Engineering v. 131 no1 (January 2005) p. 6-15
  • "The Structural Steel of the World Trade Center Towers". Gayle, Frank W.; Banovic, Stephen W.; Foecke, Tim. Advanced Materials & Processes v. 162 no10 (October 2004) p. 37-9
  • "WTC Findings Uphold Structural Design" Post, Nadine M. ENR v. 253 no17 (November 1 2004) p. 10-11
  • "Numerical simulation of blast in the World Trade Center", Baum, Joseph D; Luo, Hong; Loehner, Rainald, AIAA, Aerospace Sciences Meeting and Exhibit, 33rd, Reno, NV; UNITED STATES; 9-12 Jan. 1995.
  • "Issues and strategies in the DNA identification of World Trade Center victims" Theoretical Population Biology, Volume 63, Issue 3, May 2003, Pages 173-178 C. H. Brenner and B. S. Wei

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