Some conspiracy theories contend that the collapse of the World Trade Center was caused not solely by the airliner crash damage that occurred as part of the September 11 attacks and the resulting fire damage but also by explosives installed in the buildings in advance.Clarke, Steve. "Conspiracy Theories and the Internet: Controlled Demolition and Arrested Development". Episteme, Volume 4, Issue 2, 2007, pp. 167-180. Controlled demolition theories make up a major component of 9/11 conspiracy theories.

Early advocates such as physicist Steven E. Jones, architect Richard Gage, software engineer Jim Hoffman, and theologian David Ray Griffin proposed that the aircraft impacts and resulting fires themselves alone could not have weakened the buildings sufficiently to initiate the catastrophic collapse and that the buildings would have neither collapsed completely nor at the speeds they did without additional energy involved to weaken their structures.

The National Institute of Standards and Technology (NIST) and the magazine Popular Mechanics examined and rejected these theories. Specialists in structural mechanics and structural engineering accept the model of a fire-induced, gravity-driven collapse of the World Trade Center buildings, an explanation that does not involve the use of explosives. NIST "found no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down by controlled demolition using explosives planted prior to Sept. 11, 2001." Professors Zdeněk Bažant of Northwestern University, Thomas Eagar of the Massachusetts Institute of Technology, and James Quintiere of the University of Maryland have also dismissed the controlled-demolition conspiracy theory.

In 2006, Jones suggested that thermite or super-thermite may have been used by government insiders with access to such materials and to the buildings themselves to demolish the buildings. In April 2009, Jones, Dane Niels H. Harrit and seven other authors published a paper in The Open Chemical Physics Journal, causing the editor, Prof. Marie-Paule Pileni, to resign as she accused the publisher of printing it without her knowledge; this article was titled Active Thermitic Material Discovered in Dust from the 9/11 World Trade Center Catastrophe, and stated that they had found evidence of nano-thermite in samples of the dust that was produced during the collapse of the World Trade Center towers. NIST responded that there was no "clear chain of custody" to prove that the four samples of dust came from the WTC site. Jones invited NIST to conduct its own studies using its own known "chain of custody" dust, but NIST did not investigate.

History

The controlled demolition conspiracy theories were first suggested in September 2001. Eric Hufschmid's book, Painful Questions: An Analysis of the September 11th Attack, in which the controlled demolition theory is explicitly advocated, was published in September 2002. David Ray Griffin and Steven E. Jones are the best known advocates of the theory. Griffin's book The New Pearl Harbor, published in 2004, has become a reference work for the 9/11 Truth movement. In the same year, Griffin published the book The 9/11 Commission Report: Omissions and Distortions, in which he argues that flaws in the commission's report amounts to a cover-up by government officials and says that the Bush administration was complicit in the 9/11 attacks.

Steven E. Jones has been another voice of the proponents of demolition theories. In 2006, he published the paper "Why Indeed Did the WTC Buildings Completely Collapse?". On September 7, 2006, Brigham Young University placed Jones on paid leave citing the "increasingly speculative and accusatory nature" of his statements, pending an official review of his actions. Six weeks later, Jones retired from the university. The structural engineering faculty at the university issued a statement which said that they "do not support the hypotheses of Professor Jones".

In its final report, NIST stated that it "found no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down by controlled demolition using explosives planted prior to Sept. 11, 2001. NIST also did not find any evidence that missiles were fired at or hit the towers. Instead, photographs and videos from several angles clearly show that the collapse initiated at the fire and impact floors and that the collapse progressed from the initiating floors downward until the dust clouds obscured the view" and posted an FAQ about related issues on its website in August 2006. Allegations of controlled demolition have been found to be devoid of scientific merit by mainstream engineering scholarship. The magazine Popular Mechanics also found the theories lacked scientific support in its special report "Debunking the 9/11 Myths".

Articles, letters and comments by controlled demolition advocates have been published in scientific and engineering journals. In April 2008, a letter titled "Fourteen Points of Agreement with Official Government Reports on the World Trade Center Destruction," was published by Steven E. Jones, Frank Legge, Kevin Ryan, Anthony Szamboti and James Gourley in The Open Civil Engineering Journal. A few months later, in July 2008, an article titled "Environmental anomalies at the World Trade Center: evidence for energetic materials," was published by Ryan, Gourley and Jones in the Environmentalist. Later that same year, in October 2008, the Journal of Engineering Mechanics published a comment by chemical engineer and attorney James R. Gourley, in which he describes what he considered fundamental errors in a 2007 paper on the mechanics of progressive collapse by Bažant and Verdure. In the same issue, Bažant and Le rebutted Gourley's arguments, finding his criticisms scientifically incorrect. "The interdisciplinary interests of Gourley, a chemical engineer with a doctorate in jurisprudence, are appreciated. Although none of the discusser's criticisms is scientifically correct, his discussion provides a welcome opportunity to dispel doubts recently voiced by some in the community outside structural mechanics and engineering." They suggested future critics should "become acquainted with the relevant material from an appropriate textbook on structural mechanics" or risk "misleading and wrongly influencing the public with incorrect information." "Although everyone is certainly entitled to express his or her opinion on any issue of concern, interested critics should realize that, to help discern the truth about an engineering problem such as the WTC collapse, it is necessary to become acquainted with the relevant material from an appropriate textbook on structural mechanics. Otherwise critics run the risk of misleading and wrongly influencing the public with incorrect information."

In April 2009, Danish chemist Niels H. Harrit, of the University of Copenhagen, and eight other authors published a paper in The Open Chemical Physics Journal, titled, "Active Thermitic Material Discovered in Dust from the 9/11 World Trade Center Catastrophe." The paper concludes that chips consisting of unreacted and partially reacted super-thermite, or nano-thermite, appear to be present in samples of the dust.Politiken: Konspirationsteorier om 9/11 får nyt liv, Jyllands-Posten: Forskere: Sprængstof i støvet fra WTC , Ekstra Bladet: Mystik om WTC: Nano-termit i tårne, Kristeligt Dagblad: Dansker genopliver konspirationsteori om 11. september, Videnskab: Dansk forsker: Eksplosivt nanomateriale fundet i støvet fra World Trade Center. The journal Videnskab is sponsored by the Danish Ministry for Science and Technology. The editor in chief of the publication subsequently resigned.

Internet websites and videos have contributed to the growth of the movement of individuals supporting the theory that planted explosives destroyed the World Trade Center. The website of Architects and Engineers for 9/11 Truth cites the membership of over 2,400 architects and engineers. The controlled demolition theory often includes allegations that U.S. government insiders planned and / or participated in the destruction of the WTC in order to justify the invasion of Iraq and Afghanistan. The theory features prominently in popular entertainment type movies, such as Loose Change, as well as documentaries such as 9/11: Blueprint for Truth, by San Francisco-area architect Richard Gage.

While mainstream press has a significant history of dismissing conspiracy theories (i.e., in 2006, the magazine New York reported that a "new generation of conspiracy theorists is at work on a secret history of New York's most terrible day."), the theory has been supported by a number of popular actors, musicians and politicians, including Charlie Sheen, Willie Nelson, former Governor of Minnesota Jesse Ventura, talkshow host Rosie O'Donnell, and actors Ed Asner and Daniel Sunjata.

Twin Towers

On September 11, the North Tower (1 WTC) was hit by American Airlines Flight 11 and the South Tower (2 WTC) was hit by United Airlines Flight 175, both Boeing 767 aircraft. The South Tower collapsed 56 minutes after the impact, and the North Tower collapsed 102 minutes after. An investigation by NIST concluded that the collapse was caused by a combination of damage to support columns and fire insulation from the aircraft impacts and the weakening of columns and floors by jet fuel ignited fires. NIST also found "no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down by controlled demolition using explosives planted prior to September 11, 2001".

Jones, among others, points to many descriptions by individuals working on the WTC rubble pile suggesting the presence of molten steel in the pile and a stream of molten metal that poured out of the South Tower before it collapsed as evidence of temperatures beyond those produced by the fire. Jones has argued that the molten metal may have been elemental iron, a product of a thermite reaction. Jones and other researchers analyzed samples of dust from the World Trade Center buildings and reported their findings for evidence of nano-thermite in the dust. Jones informed NIST of his findings and NIST responded that there was no "clear chain of custody" proving that the dust indeed came from the WTC site. Jones invited NIST to conduct its own studies with dust under custody of NIST itself, but NIST has not done so.

NIST found that the condition of the steel in the wreckage of the towers does not provide conclusive information on the condition of the building before the collapse and concluded that the material coming from the South Tower was molten aluminum from the plane, which would have melted at lower temperatures than steel. NIST also pointed out that cutting through the vertical columns would require planting an enormous amount of explosives inconspicuously in highly secured buildings, then igniting it remotely while keeping it in contact with the columns. The Energetic Materials Research and Testing Center performed a test with conventional thermite and was unable to cut a vertical column, despite the column being much smaller than those used in the World Trade Center. Jones and others have responded that they do not believe that thermite was used, but rather a form of thermite called nano-thermite, a nanoenergetic material developed for military use, propellants, explosives, or pyrotechnics. Historically, explosive applications for traditional thermites have been limited by their relatively slow energy release rates. But because nano-thermites are created from reactant particles with proximities approaching the atomic scale, energy release rates are far improved.