The controlled demolition hypothesis is a 9/11 conspiracy theory that claims the complete structural failure of the World Trade Center towers was not caused by the plane crash damage that occurred as part of the September 11, 2001 attacks, nor by the fire damage that followed, but by explosives or other devices planted in the buildings in advance.^[1] It was first suggested in late 2001 and has since become increasingly important to the 9/11 Truth Movement, but is rejected by the mainstream media and engineering community.^[1] CNN broadcast of September 11 destruction when the second plane struck the south tower of the WTC. According to the 9/11 Commission Report, nineteen al-Qaeda terrorists hijacked four commercial aircraft on the morning of September 11, 2001. ... For other uses, see World Trade Center (disambiguation). ... A sequential look at United Flight 175 crashing into the south tower of the World Trade Center The September 11, 2001 attacks (often referred to as 9/11—pronounced nine eleven or nine one one) consisted of a series of coordinated terrorist[1] suicide attacks upon the United States, predominantly... Members of the 9/11 Truth Movement at a Los Angeles demonstration, October 2007 The 9/11 Truth Movement is the name adopted by organizations and individuals that question the mainstream account of the September 11, 2001 attacks against the United States. ...

The most detailed statements of the hypothesis have come from physicist Steven Jones, architect Richard Gage, software engineer Jim Hoffman, theologian David Ray Griffin, and author Webster Griffin Tarpley. In addition to citing witness accounts reporting explosions in the buildings prior to collapse, proponents argue that the aircraft impacts and resulting fires could not have weakened the buildings sufficiently to initiate collapse and that the buildings would in any case not have collapsed as completely, symmetrically, and quickly as they did without an additional source of destructive energy to undermine their structure. Various sources of this energy have been proposed; the use of thermite, explosives, or some combination thereof is the most common suggestion being made today.^[2][3] Steven E. Jones For other uses, see Stephen Jones. ... Jim Hoffman is a software engineer in Alameda, California, who has worked in scientific visualization and was instrumental in producing the first visualization of Costas minimal surface. ... David Ray Griffin (born 1939) is a retired professor of philosophy of religion and theology and a proponent of an alternative 9/11 theory that implicates members of the United States government as being involved in the attacks. ... Webster G. Tarpley (left) with William Rodriguez (right) on the 9/11 + The Neo-Con Agenda Symposium Webster Griffin Tarpley is an author, lecturer, and critic of US foreign and domestic policy which he has termed the Anglo-American oligarchical empire. He maintains that the events of 9/11 were... A thermite mixture using Iron (III) Oxide A thermite mixture using Iron (II,III) Oxide Thermite is a kind of pyrotechnic composition of aluminium powder and a metal oxide which produces an aluminothermic reaction known as a thermite reaction. ... This article is concerned solely with chemical explosives. ...

The National Institute of Standards and Technology (NIST), an agency of the United States Department of Commerce, has rejected the hypothesis that collapse due to fire would be impossible, as has the engineering community.^[4] Members of the 9/11 Truth movement have requested correction of the NIST report.^[5] NIST logo The National Institute of Standards and Technology (NIST, formerly known as The National Bureau of Standards) is a non-regulatory agency of the United States Department of Commerce’s Technology Administration. ... The United States Department of Commerce is a Cabinet department of the United States government concerned with promoting economic growth. ... The 9/11 truth movement is a name for individuals and groups who seek to find what they see as the truth behind the attacks on September 11 2001. ...

History

Controlled demolition hypothesis proponents cite mainstream news reports on the day of the attacks that suggested explosions and secondary devices.^[6] Journalists and experts commenting on the events as they happened speculated that the World Trade Center collapses were caused by intentionally planted explosives. ABC News anchor Peter Jennings said "Anybody who ever watched a building being demolished on purpose knows that if you're going to do this you have to get at the under infrastructure of a building and bring it down"^[7] While watching footage of the collapse of WTC 7, CBS News anchor Dan Rather said "For the third time today, its reminiscent of those pictures we've all seen too much on television before when a building was deliberately destroyed by well-placed dynamite to knock it down."^[8] Some of these suggestions would later be retracted or revised. In a notable example, the Albuquerque Journal quoted Dr. Van D. Romero, an engineer who said that the collapses looked "too methodical" and that "some explosive devices inside ... caused the towers to collapse", speculating that the collision of the planes into the towers was a diversionary attack intended to attract emergency personnel to the scene, followed by the detonation of "a relatively small amount of explosives placed in strategic points" of the towers as the primary attack.^[9] He soon withdrew this assessment^[10] and later said he had been misquoted: "I only said that that's what it looked like."^[11] Members of the 9/11 Truth Movement at a Los Angeles demonstration, October 2007 The 9/11 Truth Movement is the name adopted by organizations and individuals that question the mainstream account of the September 11, 2001 attacks against the United States. ... A variety of conspiracy theories question the mainstream account of the September 11, 2001 attacks against the United States. ... Since the September 11, 2001 attacks, a minority of people have expressed doubts about the official account of events. ... Nafeez Mosaddeq Ahmed is author, born in London from Bangladeshi origin. ... Charles Chuck Baldwin (born May 3, 1952 in La Porte, Indiana) is an American political figure, activist within the Constitution Party, and Baptist minister. ... The name Kevin Barrett may also refer to Kevin Buzz Barrett, a former cast member of ZOOM, Kevin James Barrett (born February 1959) is a university lecturer and 9/11 conspiracy theorist. ... Robert M. Bowman (born 1934) was the former Director of Advanced Space Programs Development for the U.S. Air Force in the Ford and Carter administrations, and a former United States Air Force Lieutenant Colonel with 101 combat missions. ... Andreas von Bülow (born 17 July 1937 in Dresden) is a German writer, lawyer and former SPD politician. ... Alexander Keewatin Dewdney (born August 5, 1941 in London, Ontario) is a Canadian mathematician, computer scientist and philosopher who has written a number of books on the future and implications of modern computing. ... Rosie ODonnell (born March 21, 1962 in Bayside, Queens, New York) is an 11-time Emmy Award-winning American talk show host, television personality, comedienne, film, television, and stage actress. ... Image:James H. Fetzer. ... David Ray Griffin (born 1939) is a retired professor of philosophy of religion and theology and a proponent of an alternative 9/11 theory that implicates members of the United States government as being involved in the attacks. ... Sander Hicks is the founder and former editor of Soft Skull Press as well as playwright. ... Jim Hoffman is a software engineer in Alameda, California, who has worked in scientific visualization and was instrumental in producing the first visualization of Costas minimal surface. ... For other persons of the same name, see Alex Jones. ... Steven E. Jones For other uses, see Stephen Jones. ... For other persons named David Lynch, see David Lynch (disambiguation). ... Lynn Margulis Dr. Lynn Margulis (born March 15, 1938) is a biologist and University Professor in the Department of Geosciences at the University of Massachusetts Amherst. ... Michael Hugh Meacher (born November 4, 1939) is a British Labour party politician, and Member of Parliament (MP) for Oldham West and Royton. ... Thierry Meyssan Thierry Meyssan is a French journalist and extreme left political activist. ... Morgan Reynolds Morgan O. Reynolds is professor emeritus at Texas A&M University and former director of the Criminal Justice Center at the National Center for Policy Analysis headquartered in Dallas, TX. He served as chief economist for the United States Department of Labor during 2001–2002, George W. Bush... For other persons named Paul Roberts, see Paul Roberts (disambiguation). ... Rodriguez & US President George W Bush William Rodríguez is a former janitor who was at the North Tower of the World Trade Center who pulled several people to safety during the September 11, 2001 attacks. ... Michael Ruppert is the founder and editor of From The Wilderness, a newsletter and website dedicated to investigating political cover-ups. ... Peter Dale Scott is a poet, antiwar activist, and professor emeritus, University of California, Berkley who wrote a tract entitled The War Conspiracy, in which he alleges that certain of the American government and economy conspire to maintain the status quo by manipulating our armed forces in an effort to... David Shayler talking at an anti-war meeting at Sheffield University David Shayler is a British journalist and former MI5 (British Security Service) officer. ... Charles Irwin Sheen (born September 3, 1965) is a Golden Globe Award-winning and Emmy-nominated American actor. ... Martin Sheen (born August 3, 1940) is an Emmy- and Golden Globe Award-winning American actor. ... This article is being considered for deletion in accordance with Wikipedias deletion policy. ... James (Jimmy) W. Walter of Amsterdam, Netherlands and Vienna, Austria is a venture capitalist, philanthropist and political activist of the United States who is a proponent of the 9/11 domestic conspiracy theory. ... Barrie Wallace Zwicker (1934-present) is an award-winning Canadian alternative media journalist, documentary producer, and left-wing political activist. ... 9-11 Citizens Watch is a citizen-led watchdog network established to support independent investigation, research and analysis into the attacks of September 11th and its political and economic aftermath. ... The Family Steering Committee was an organization of twelve relatives of victims the September 11, 2001 attacks on the World Trade Center. ... The Jersey Girls or Jersey Widows is a commonly-used moniker referring to four women from New Jersey, (Kristen Breitweiser, Patty Casazza, Lorie Van Auken, and Mindy Kleinberg), whose husbands were killed in the September 11, 2001 attacks. ... The stark front cover includes the seal of the CIA The CIA and September 11 (German: Die CIA und der 11. ... The New Pearl Harbor: Disturbing Questions About the Bush Administration and 9-11 (2004, ISBN 1-56656-552-9) is a book written by David Ray Griffin, a retired professor of philosophy at the Claremont School of Theology. ... The Terror Timeline: Year by Year, Day by Day, Minute by Minute: A Comprehensive Chronicle of the Road to 9/11 — and Americas Response is described by its publisher as a compilation of over 5,000 reports and articles concerning the September 11, 2001 attacks. ... The War on Freedom: How and Why America was Attacked, is a book about the 9/11 attacks, coauthored by poet John Leonard and 9/11 Truth Movement activist Nafeez Mosaddeq Ahmed. ... ABC News logo ABC News Special Report ident, circa 2006 ABC News is a division of American television and radio network ABC, owned by The Walt Disney Company. ... Peter Charles Archibald Ewart Jennings, CM (July 29, 1938 – August 7, 2005) was a Canadian-American journalist and news anchor. ... CBS News logo, used from Sept. ... Daniel Irvin Rather, Jr. ...

Engineers were in fact initially surprised by the collapses^[12][13][14] and at least one considered explosives as a possible explanation.^[15] The broad outlines of an explanation that did not involve such explosives quickly emerged, however, and took its current shape in the 2005 NIST report.^{[16] [17]} It has come to be known as "the official account" among proponents of controlled demolition.^[18] Ground Zero debris with markup showing building locations. ...

The hypothesis was first suggested as a part of a conspiracy theory in October 2001.^[1] An early book-length treatment of the hypothesis^[19] inspired both David Ray Griffin's critical inquiry^[18] as well as the Popular Mechanics investigation of 9/11 conspiracy theories.^[11] In late 2005, Brigham Young University Professor of Physics Steven Jones made his own pursuit of the hypothesis public.^[2] Even before publication of the article in 2006,^[20] his interest in the hypothesis brought a measure of scientific credibility and media exposure to the theory. BYU responded to Jones' "increasingly speculative and accusatory" statements by placing him on paid leave in September, 2006.^[21][22] Shortly thereafter, Jones accepted BYU's offer of early retirement. The adolescent Internet. ... , Brigham Young University (BYU), located in Provo, Utah, is a private coeducational school completely owned by The Church of Jesus Christ of Latter-day Saints (LDS or Mormon Church) and run under the auspices of its Church Educational System. ...

Proponents of the controlled demolition have questioned the "pancake collapse" hypothesis originally suggested by FEMA^[23] which the NIST also rejected and finally replaced with the current column failure theory.^[17]

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 September 11, 2001"^[24] and posted a FAQ about related issues to its website in August of 2006.^[17] The major elements of the hypothesis have been rebutted in mainstream engineering scholarship,^[14] where its proponents are considered "outsiders".^[4]

A 2006 poll found that 6 percent of Americans considered it "very likely" that "the collapse of the twin towers in New York was aided by explosives secretly planted in the two buildings", while another 10% found it "somewhat likely". 77% found the demolition hypothesis "unlikely".^[25] A 2007 poll found that 67% of Americans fault the 9/11 Commission for not investigating the collapse of World Trade Center 7.^[26]

In June 2008, Arizona State Senator Karen Johnson delivered a letter to the office of U.S. Senator John McCain asking him to meet with a group of professionals to discuss the events of 9/11.^[27] She also gave a speech on the floor of the Arizona Senate^[28] that included her support for the demolition theory, its proponents, and its relevance to current foreign policy in the US. Johnson said in her speech:

"You don’t have to embrace every theory about 9/11. Indeed, there are some that should be soundly rejected. But if you believe, as these scientists, architects and engineers do, that the buildings were brought down by explosive demolition, then you must also agree that we need a new investigation. I have no preconceived notions about who did it and I am not pointing the finger of blame at anyone. But I do think that the worst attack on U.S. soil in American history deserves the best investigation possible."

World Trade Center Seven

Building damage to the southwest corner and smoke plume along the South face of WTC 7, looking from the World Financial Plaza.

The position of Building 7 in relation to the other WTC buildings. WTC 1, 2, and 7 collapsed on September 11, 2001.

7 World Trade Center was a 47-story steel-framed skyscraper that stood across Vesey Street north of the main WTC complex. Its tenants included the CIA, Department of Defense, IRS, Secret Service and the Securities and Exchange Commission. Though not hit by a plane, it collapsed at about 5:20 p.m. EDT on the evening of September 11, 2001. Image File history File links WTC7. ... Image File history File links WTC7. ... Image File history File links WTC_Building_Arrangement_and_Site_Plan_(building_7_highlighted). ... Image File history File links WTC_Building_Arrangement_and_Site_Plan_(building_7_highlighted). ... is the 254th day of the year (255th in leap years) in the Gregorian calendar. ... This article is about the year. ... 7 World Trade Center is a building in New York City located across from the World Trade Center site in Lower Manhattan. ... CIA redirects here. ... The United States Department of Defense (DOD or DoD) is the federal department charged with coordinating and supervising all agencies and functions of the government relating directly to national security and the military. ... Seal of the Internal Revenue Service Tax rates around the world Tax revenue as % of GDP Part of the Taxation series        IRS redirects here. ... USSS redirects here. ... The Securities and Exchange Commission, commonly referred to as the SEC, is the United States governing body which has primary responsibility for overseeing the regulation of the securities industry. ... is the 254th day of the year (255th in leap years) in the Gregorian calendar. ... This article is about the year. ...

Some journalists commenting on the nature of the collapse of WTC 7 said that it resembled a controlled demolition,^[29][30] although the explanation that fires in the building, started by falling debris from the collapse of WTC 1, had caused the structure to fail, quickly emerged. No steel-frame high rise had ever before collapsed because of a fire.^[31] BBC News reported the collapse of WTC 7 twenty minutes before it actually fell. The BBC has stated that many news sources were reporting the imminent collapse of WTC 7 on the day of the attacks.^[32]. The reporter who announced the collapse prematurly Jane Stanley called it a "very small and very honest mistake" caused by her thinking on her feet after being confronted with a report she had no way of checking.^[33] For other uses, see BBC (disambiguation). ...

In a New York Magazine interview in March 2006, Dr S. Shyam Sunder, NIST's lead WTC disaster investigator granted that they were having "trouble getting a handle on Building No. 7".^[34] NIST has postponed publication of its report several times, attributing the delays to reassignment of investigators to other tasks such as the main towers investigation. The initial FEMA investigation report noted that its "best hypothesis has only a low probability of occurrence" and called for a more thorough investigation.^[35]

In addition to its remaining unexplained, proponents of controlled demolition often emphasize the collapse of WTC 7 because its collapse looked like a bottom-to-top conventional controlled demolition, as opposed to the more explosive top-to-bottom collapses of the two main towers. Support for this theory comes from features argued to have been visually observed in the collapse--the speed of the collapse, the way it fell down vertically and symmetrically, the rapid onset, the way the center of the roof fell first, lateral ejections of debris observed, and the way the rubble fell mostly within the building's footprint.^{[citation needed]} The initial FEMA investigation team also found sulfur within the structural steel from WTC 7 which they could not explain: "The severe corrosion and subsequent erosion of Samples 1 and 2 are a very unusual event. No clear explanation for the source of the sulfur has been identified. The rate of corrosion is also unknown. It is possible that this is the result of long-term heating in the ground following the collapse of the buildings. It is also possible that the phenomenon started prior to collapse and accelerated the weakening of the steel structure. A detailed study into the mechanisms of this phenomenon is needed to determine what risk, if any, is presented to existing steel structures exposed to severe and long-burning fires."^[36]. Steven Jones claims that sulphur is evidence that indicates the use of explosives such as thermate, along with reports of molten metal and extremely high temperatures in the rubble.^[2] However, Prof. Richard Sisson asserts that the sulfur came from gypsum in the wallboards.^[37] This article is about the chemical element. ... Thermate is an incendiary compound used for military applications and controlled demolition. ...

WTC 7 at the moment of collapse: the shape of the roof and debris plumes are cited as evidence for controlled demolition.

In the PBS documentary America Rebuilds, which aired in September 2002, Larry Silverstein, the owner of WTC 7 and leaseholder and insurance policy holder for the remainder of the WTC Complex, recalled a discussion with the fire department in which doubts about containing the fires were expressed. Silverstein recalled saying, "We've had such terrible loss of life, maybe the smartest thing to do is pull it". "They made that decision to pull", he recalled, "and we watched the building collapse." Some proponents of the controlled demolition hypothesis have taken the remark as a confession that he ordered the building to be demolished.^[38] Silverstein issued a statement that rejects this interpretation, asserting that it was the firefighting team, not the building, that was to be pulled.^[39] 7 World Trade Center Larry A. Silverstein (born 1932) is an American billionaire real estate investor and operator and the head of Silverstein Properties, a real estate development group. ...

Hugo Bachmann and Jörg Schneider, professors emeritus of structural engineering at the Swiss Federal Institute of Technology, believe that WTC 7 was intentionally demolished based on video footage.^[40] The 9/11 Family Steering Committee also asked what happened to WTC 7 in their 'Questions Regarding the 9/11 Commission Interview of Mayor Rudy Giuliani,' asking, "On 9/11, no aircraft hit WTC 7. Why did the building fall at 5:20 PM that evening?"^[41] ETH Zurich (from its German name Eidgenössische Technische Hochschule Zürich, ETHZ) is the Swiss Federal Institute of Technology in Zürich, Switzerland. ... The Family Steering Committee was an organization of twelve relatives of victims the September 11, 2001 attacks on the World Trade Center. ...

In 2002 The National Institute of Standards and Technology began investigating the collapse of this building as part of its general probe but split off the investigation of this buildings collapse. Its final report on the collapse of building 7 is due in August 2008. The agency has blamed the slowness of this investigation on the complexity of the computer model it is using, which simulates the collapse from the moment it begins all the way to the ground. The agency also notes another 80 boxes of documents related to WTC7 have also been found and need to be analysed. These delays have caused suspicion that the agency is struggling to come up with a plausible line of obfuscation^[42]. NIST logo The National Institute of Standards and Technology (NIST, formerly known as The National Bureau of Standards) is a non-regulatory agency of the United States Department of Commerce’s Technology Administration. ... 2008 (MMVIII) will be a leap year starting on Tuesday of the Gregorian calendar. ...

Preliminary investigations do not include the mechanics of the actual collapse, concentrating instead on the events leading up to it. The FEMA report begins its "timed collapse sequence" with a seismic event recorded at 5:20:33 pm. FEMA marks this as the time the building "begins to collapse". At this time, the report says, the east and west mechanical penthouses — the structures at the very top of the building — are still intact. Approximately thirty seconds later, FEMA says, video evidence shows the east mechanical penthouse begin to disappear into the building. Five seconds later the west penthouse also disappears, and at 5:21:10 "WTC 7 collapses completely".^[43] This is roughly the point at which proponents of the controlled demolition hypothesis begin timing the collapse, noting that the observed times correspond with the free, unimpeded fall of the roofline: just under seven seconds.^[2]

According to a BBC News the final NIST report will conclude that ordinary fires caused the building to collapse. It will conclude that a combination building seven’s unusual design, its location over subways and a electrical substation as well the firefighters lack of water and their prioritizing saving lives caused the fires to burn for hours. According to the report “fires burnt long enough to weaken and break many of the connections that held the steel structure together. Most susceptible were the thinner floor beams which required less fireproofing, and the connections between the beams and the columns. As they heated up the connections failed and the beams sagged and failed, investigators say”. Dr Shyam Sunde the lead investigator told the BBC that the investigators had to use four complex computer models because of the lack of steel and noted that two to two and half years is the normal time for an investigation of this complexity.^[44] ” This article refers to the news department of the British Broadcasting Corporation, for the BBC News Channel see BBC News (TV channel). ...

Main towers

The controlled demolition hypothesis is also offered to explain dramatic collapses of the two main towers of the World Trade Center complex on September 11, 2001. It emphasizes the speed, symmetry and totality of the collapses, which, it suggests, could not have been caused by the airplane crashes alone. The effects of the fires and the progress of the collapses after they began have been the main areas of contention.^[2]

The hypothesis suggests that the fires could not have been hot enough to weaken the steel structure of the two towers to the point of collapse. However, those who pursue the hypothesis emphasize evidence of temperatures well beyond those that, by general consensus, can be attributed to the fires. Molten metal streamed out of the south tower shortly before it collapsed.^[17] There are first-hand reports of claims that molten metal was discovered in the piles of rubble in the weeks following the collapses.^[45][46] Steven Jones has argued that the molten metal may have been iron, a byproduct of a thermite reaction. Thermite reactions can reach temperatures of up to 4500°F (2500°C), well beyond the temperature (approximately 1500°C (2732°F) required to melt structural steel.^[2] A thermite mixture using Iron (III) Oxide A thermite mixture using Iron (II,III) Oxide Thermite is a kind of pyrotechnic composition of aluminium powder and a metal oxide which produces an aluminothermic reaction known as a thermite reaction. ...

In response, NIST has 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.^[17] NIST speculated that some of the observed molten metal may have been molten aluminum from the fuselage of the plane. Aluminum melts at significantly lower temperatures than steel. Aluminum is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air. ...

The controlled demolition hypothesis is also offered to explain a belief that the towers collapsed close to free fall speed. Most estimates agree that the structures offered little resistance to the progress of the collapses and that they took about 50% longer than a free falling object dropped from the tops of the towers. Without explosives to destroy the internal support structure of the WTC towers, argue proponents of controlled demolition, the fall of the towers would violate the principle of conservation of momentum.^[2][47] Others say that these claims are only supported by intuition without any quantitative analysis. They point to their own analyses posted on a website suggesting that the fall may be explained without violating the principle of conservation of momentum and without requiring any explosives.^[48][49] Ground Zero debris with markup showing building locations. ... In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves. ...

The official account does not describe any damage to the structure beneath the impact zone and attempts to confirm or refute the controlled demolition hypothesis by modeling the collapses of WTC 1 and 2 have not borne fruit. An early effort indicated that once collapse began, the kinetic energy imparted by a falling upper section onto the floor below was at least ten times greater than that which the lower section could support.^[4] The NIST report provides an analysis of the structural response of the building only up to the point where collapse begins, and asserts that the enormous kinetic energy transferred by the falling part of the building makes "progressive collapse" inevitable once an initial collapse occurs. Supporters of the controlled demolition hypothesis often emphasize that NIST did not simulate the structural response of the lower parts of the buildings, which they find of primary interest, but do not analyze either.^[2]

Engineers who have investigated the collapses generally deny that controlled demolition is required to understand the structural response of the buildings. While the top of one of the towers did tilt significantly, it could not ultimately have fallen into the street, they argue, because any such tilting would place sufficient stress on the lower story (acting as a pivot) that it would collapse long before the top had sufficiently shifted its center of gravity. Indeed, they argue, there is very little difference between progressive collapse with or without explosives in terms of the resistance that the structures could provide after collapse began.^[50][4]

First, proponents often encourage their audiences to compare the video footage of the collapses of the WTC towers with footage of known controlled demolitions. Among the most commonly cited similarities are tightly focused horizontal plumes of smoke and debris being ejected from the twin towers just before and during the collapse. While these plumes are normally attributed to material ejected due to the compression of air as the floors collapsed,^[17] they are sometimes taken as evidence for exploding demolition charges ("squibs") by proponents of controlled demolition.^[2][38] Second, they cite a large number of eyewitness accounts made by firefighters and emergency medical responders of explosions just prior to the start of the collapse of the towers as evidence for controlled demolition.^[51][52] Finally, the production and expansion of the enormous dust clouds that covered Manhattan after the collapses have also been taken as an indication of an additional source of energy, such as explosives. Some conspiracy theorists suggest that the energy required for this expansion alone (ignoring the energy needed to slice the steel and pulverize the concrete and other materials) exceeded the gravitational energy available by 9.7 × 10¹² J to 4.2 × 10¹³ J.^[38][53] This corresponds to extra energy of about 2000 to 10000 tons of TNT, or 40 to 200 times the yield of the most powerful conventional bomb. NIST attributes these clouds to the ejection of air from compressed parts of the building.^[16] The joule (IPA: or ) (symbol: J) is the SI unit of energy. ... The joule (IPA: or ) (symbol: J) is the SI unit of energy. ... Unit of energy commonly used to quantify laerge amounts of energy. ... Father of All Bombs is the nickname of a Russian-made air-delivered/land activated thermobaric weapon that is claimed to be four times more powerful than the U.S. militarys GBU-43/B Massive Ordnance Air Blast bomb (MOAB or the mother of all bombs), making it the...

Debris removal

Most of the structural steel in the World Trade Center was removed from the site and recycled before it could be examined by engineers.^[54] Proponents of controlled demolition often see this as part of a cover up. Webster Griffin Tarpley, an author, has criticized the official response to the crime scene, saying the speedy cleanup resulted in the destruction of most of the evidence, identifying the New York City Mayor's office as a key player in this regard.^[55] ...

According to Fox News, the debris removal process began shortly after the attacks, and concluded in May 2002.^[56] Some members of the 9/11 Truth Movement allege that engineers were not granted access to Ground Zero until most of the debris had been removed, while others allege that engineers were not granted access to Ground Zero or even the salvage yards at all.^[57] However, Robert F. Shea of FEMA testified to the House of Representatives that, "Because of the importance of the rescue effort at the World Trade Center complex, it was clear that information would have to be gathered without interfering with response and rescue activities. Based on this fact, the FEMA-ASCE team first visited the site on October 6, [2001] but gathered information from others who had been on-site before this date.^[58] And access to the scrap yards? Appendix D of the FEMA report states that, "As of March 15, 2002, a total of 131 engineer visits had been made to these yards on 57 separate days."^[59]

A call to action by Bill Manning, the chief editor of the trade journal Fire Engineering, is often quoted in this connection. Manning called the early ASCE investigation (which would later turn into the FEMA building performance study) a "half-baked farce" and said that "the destruction and removal of evidence must stop immediately." He said that the cleanup of the WTC site differed in many respects from that of other engineering disasters.^[60] In defense of the decision to dispose of the steel, Mayor Bloomberg said: "If you want to take a look at the construction methods and the design, that's in this day and age what computers do."^[61] David Ray Griffin notes that this is exactly what Manning had worried about when he warned that "the investigation into the World Trade Center fire and collapse will amount to paper-and computer-generated hypotheticals."^[38]

Dr. Gene Corley's Opinion

However, allegations against a "speedy removal" of the steel hampering the engineering investigations appear to be unfounded, according to Dr. Gene Corley, head of the BPAT team and one of the lead engineers for the investigation by the National Institute of Standards and Technology (NIST), which began in September 2002. He testified to the House of Representatives in March 2002 that, "There has been some concern expressed by others that the work of the team has been hampered because debris was removed from the site and has subsequently been processed for recycling. This is not the case. The team has had full access to the scrap yards and to the site and has been able to obtain numerous samples. At this point there is no indication that having access to each piece of steel from the World Trade Center would make a significant difference to understanding the performance of the structures".^[62]

Notable proponents

The most notable statements of the controlled demolition hypothesis have been made by Steven Jones, David Ray Griffin, Webster Griffin Tarpley and Kevin Ryan. Jones has published his paper "Why Indeed Did the World Trade Center Buildings Collapse?"^[2] in a book called 9/11 and the American Empire: Intellectuals Speak Out, edited by Peter Dale Scott and David Ray Griffin.^[20] Griffin, a retired professor of theology, published his own version of the hypothesis in The Hidden History of 9-11-2001,^[63] a book of critical essays on 9/11 edited by Paul Zarembka. Webster Griffin Tarpley has devoted a chapter of his book 9/11 Synthetic Terror^[55] to the hypothesis. Kevin Ryan, who was fired from his job at Underwriters Laboratories for voicing his criticism of the official investigation, has also contributed a chapter to the Griffin and Scott volume.^[20] While his work remains largely self-published, Jim Hoffman's detailed web site, 9-11 Research, is often cited by proponents of the controlled demolition hypothesis as an inspiration.^[38] Peter Dale Scott is a poet, antiwar activist, and professor emeritus, University of California, Berkley who wrote a tract entitled The War Conspiracy, in which he alleges that certain of the American government and economy conspire to maintain the status quo by manipulating our armed forces in an effort to... David Ray Griffin (born 1939) is a retired professor of philosophy of religion and theology and a proponent of an alternative 9/11 theory that implicates members of the United States government as being involved in the attacks. ... ... Jim Hoffman is a software engineer in Alameda, California, who has worked in scientific visualization and was instrumental in producing the first visualization of Costas minimal surface. ...

Criticism of the NIST Report

Criticism of the NIST Report plays a prominent role in presentations of the hypothesis. Critics point out that the report does not provide an account of the structural behaviour of the towers after the collapses began.^[64] This is important because "much of the external evidence for controlled demolition typically comes after collapse initiation".^[65] It is argued that not modelling the totality of the collapses allowed NIST to ignore evidence of demolition, such as the complete, rapid and symmetrical nature of the collapses, the observed explosive "squibs", the early drop of the North Tower antenna, and the pools of molten metal found in the rubble.^[66] Kevin Ryan's criticism of the NIST investigation and subsequent report is often mentioned in this regard.^[67] Jones also criticises NIST for "tweaking" the computer simulations of the pre-collapse sequence "until [it got] the desired result.”^[68] Jones goes on to quote the NIST report itself as proof for this claim, "The Investigation Team then defined three cases for each building by combining the middle, less severe, and more severe values of the influential variables. Upon a preliminary examination of the middle cases,it became clear that the towers would likely remain standing...The more severe case was used for the global analysis of each tower..To the extent that the simulations deviated from the photographic evidence or eyewitness reports"^[69]

On February 28, 2007, NIST's conclusion 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 September 11, 2001" was challenged in a request for correction (per Section 515 of Public Law 106-554). The request was based on NIST's acknowledgement that it did not investigate controlled demolition nor look for evidence.^[70]

The investigation of 7 World Trade Center is ongoing; it has been delayed for a number of reasons, including that NIST staff who had been working on 7 World Trade Center were assigned full-time from June 2004 to September 2005, to work on the investigation of the collapse of the twin towers.^[71] NIST anticipates the release of a draft report of 7 World Trade Center in 2008.^[72] The NIST is utilizing ANSYS to model events leading up to collapse initiation and LS-DYNA models to simulate the global response to initiating events.^[73] ANSYS, Inc. ... LS-DYNA is an advanced general-purpose multiphysics simulation software package that is actively developed by the Livermore Software Technology Corporation (LSTC). ...

Reaction of the engineering community

The controlled demolition hypothesis has been dismissed in the structural engineering literature.^[4][74] Northwestern University Professor of Civil Engineering Zdeněk Bažant, who was the first to offer a published peer reviewed hypothesis of the collapses, mentions the controlled demolition hypothesis in passing in a 2007 paper, co-authored with Mathieu Verdure. Affirming the view as presented in the NIST report, they note "a few outsiders claiming a conspiracy with planted explosives" as an exception. Bažant and Verdure trace such "strange ideas" to a "mistaken impression" that safety margins in design would make the collapses impossible. One of the effects of a more detailed modeling of the progressive collapse, they say, could be to "dispel the myth of planted explosives". Indeed, Bažant and Verdure have proposed examining data from controlled demolitions in order to better model the progressive-collapse of the towers, suggesting that progressive collapse and controlled demolition are not two separate modes of failure (as the controlled demolition hypothesis assumes).^[4] Northwestern University (NU) is a private, nonsectarian, coeducational research university with campuses located in Evanston, Illinois and downtown Chicago. ... The Petronas Twin Towers, designed by Thornton-Tomasetti and Ranhill Bersekutu Sdn Bhd engineers, and Cesar Pelli, were the worlds tallest buildings from 1998 to 2004. ... ZdenÄ›k Pavel Bažant (b. ...

Thomas Eagar, a professor of materials science and engineering at the Massachusetts Institute of Technology, also dismissed the controlled demolition hypothesis.^[75] Eagar remarked, "These people (in the 9/11 truth movement) use the 'reverse scientific method.' They determine what happened, throw out all the data that doesn't fit their conclusion, and then hail their findings as the only possible conclusion."^[76] Finally, Leslie Robertson, who helped design the Twin Towers, debated Steven Jones on a radio program in December 2006.^[77][78]

In April 2008, a letter by advocates of the demolition hypothesis was published as a paper in an online peer-reviewed civil engineering journal.^{[23] [79]} They have also created organizations toward associating professionals in architecture and engineering. ^[80]

In popular culture

The demolition hypothesis first entered mainstream media by way of negative press coverage of "9/11 conspiracy theories" or "9/11 myths". Critical articles in Popular Mechanics, which were later expanded into a book, and the popular magazine Skeptic^[81] presented rebuttals to the hypothesis for a mainstream audience. In 2006, a New York Magazine reported that, "A new generation of conspiracy theorists is at work on a secret history of New York’s most terrible day."^[34] The hypothesis has been cited by numerous popular actors, musicians and politicians, including Charlie Sheen.^[82], Martin Sheen, Willie Nelson, Mos Def, and former Governor of Minnesota, Jesse Ventura. The hypothesis also features prominently in the controversial online documentary Zeitgeist, the Movie. Charles Irwin Sheen (born September 3, 1965) is a Golden Globe Award-winning and Emmy-nominated American actor. ... Martin Sheen (born August 3, 1940) is an Emmy- and Golden Globe Award-winning American actor. ... Willie Hugh Nelson (born April 30, 1933) is an American singer-songwriter and actor. ... Dante Terrell Smith (born December 11, 1973), better known by his stage name Mos Def, is a Golden Globe and Emmy Award-nominated and Grammy Award-nominated acclaimed American actor and MC, respectively. ... Jesse Ventura (born July 15, 1951 as James George Janos), also known as The Body, The Star, and The Governing Body, is an American politician, retired professional wrestler, Navy UDT veteran, actor, and former radio and television talk show host. ... For other uses, see Zeitgeist (disambiguation). ...

References