World Trade Center controlled demolition conspiracy theories

Main article: 9/11 conspiracy theories

File:South WTC Collapse.jpg

The South Tower destruction viewed from across the Hudson River

According to the controlled demolition hypotheses, the World Trade Center was not destroyed by the planes that crashed into it as part of the September 11th attacks, nor by the fires that followed, but by explosives or other devices planted in the buildings in advance. Although an investigation by the National Institute of Standards and Technology (NIST) overlooked this as an explanation for what happened, it has become central theme for many members of the 9/11 Truth Movement. The most detailed statements of the hypothesis have come from Steven E. Jones, Kevin Ryan, Jim Hoffman, David Ray Griffin and Webster Griffin Tarpley. In making their case, they often emphasize the collapse of 7 World Trade Center, which was not hit by a plane. Several organizations which associate skeptics of the known evidence of the collapse have been created; part of their focus being directed on criticizing NIST report.

Others, such as former Professor of Mechanical Engineering from Clemson University and physicist Judy Wood, whose claims have been questioned by most other demolition hypothesis proponents, say that the observed pulverization of the twin towers and damage to surrounding WTC buildings could only have been accomplished by exotic weaponry, such as a directed energy weapon, possibly space-based.

The idea of controlled demolition is normally presented as a hypothesis still to be tested, not a proven claim. Establishment engineers dismiss it as a so-called conspiracy theory.

Overview

On the morning of September 11, 2001, ten terrorists affiliated with al-Qaeda crashed passenger airliners into the World Trade Center in New York City. Soon afterward both buildings collapsed and irreparable damage to nearby buildings occurred.

While some engineers were initially surprised by the speed of the collapse of the World Trade Center, the broad outlines of a collapse theory quickly emerged in the days that followed the attacks of September 11, 2001. The details have been significantly revised as investigations proceeded, but some engineers have consistently attributed the collapse of the main towers to the combination of structural damage from the impact of the planes and weakening of the steel frame due to the resulting fires. Although the investigation into the collapse of WTC 7 has not yet been completed, the working hypothesis also suggests a combination of structural damage and weakening by fire although there is no precedent for fire causing the collapse of similar steel framed structures.

Proponents of the controlled demolition hypothesis are critical of the NIST report. Specifically, they question the idea that fire could weaken the buildings sufficiently to initiate collapse (even given the structural damage). They claim that after the collapses began, the buildings collapsed completely, straight down, and at near free-fall speed; therefore, they argue, there must have been an additional source of destructive energy. The additional energy needed to undermine the structure, it is argued, must have come from secondary devices planted in the building before September 11, 2001. In addition to this basic disagreement with the explanation, proponents of the controlled demolition hypothesis point to a variety of features of the actual collapses that, they argue, are more consistent with demolition than gravity-driven progressive collapse. These features appear mainly in stages of the collapses that the investigation did not deem relevant to understanding how they happened.

There has been some more technical criticism of the hypothesis, however. 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" and posted an FAQ about related issues to its website in August of 2006. The hypothesis has also never been suggested in mainstream engineering scholarship, where its proponents are considered "outsiders". Technical criticism of the controlled demolition hypothesis normally involves a combination of a defense of the mainstream account of the collapses and an emphasis on the insurmountable difficulties of arranging the demolition of such large buildings covertly. This difficulty is also normally invoked by proponents of the hypothesis to suggests its key implication, namely, that the nineteen terrorists who have been held responsible for causing the collapses could not have done so on their own.

Implications and reception

The controlled demolition hypothesis is sometimes offered as part of an argument for "inside" complicity in the September 11 attacks. While the hypothesis itself does not depend on identifying conspirators explicitly, it is generally believed (by both critics and proponents) that demolishing the buildings would require extraordinary access to them. Since the buildings were strategically important to US interests, and housed a number of government agencies, hypothetical bombers would very likely have had help from the inside.

An August 2006 poll concluded that 36% of respondents overall said it is "very likely" or "somewhat likely" that federal officials either participated in the attacks on the World Trade Center and the Pentagon or took no action to stop them "because they wanted the United States to go to war in the Middle East." The same poll found that 16 percent of Americans considered it at least somewhat likely that "the collapse of the twin towers in New York was aided by explosives secretly planted in the two buildings."

History

On the day of the attacks, there were reports suggesting explosions and secondary devices. Several journalists reporting on the events speculated that the World Trade Center collapses were caused by intentionally planted explosives and some experts made similar suggestions in the days following the attacks. As a mainstream explanation that did not involve explosives emerged, however, these speculations ceased, and some were retracted.

In a notable example, the Albuquerque Journal quoted Van Romero, Vice President for Research at New Mexico Institute of Mining and Technology, who said that the collapses looked "too methodical" and that his opinion, based on the videotapes, was that there were some explosive devices inside that caused the towers to collapse. He further said "detonation of bombs within the towers is consistent with a common terrorist strategy." After speaking with structural engineers, however, he revised his opinion and said "certainly the fire is what caused the building to fail". He further said he had been misquoted and had "only said that that's what it looked like."

An early version of the controlled-demolition hypothesis, explicitly stated in opposition to the mainstream explanation, was formulated by J. McMichael. His ironic essay "Muslims Suspend the Laws of Physics" recalled Romero's initial remarks and introduced some of the lasting elements of the hypothesis: that the fires could not have sufficiently weakened the steel to initiate the collapses, and that the undamaged structure underneath the impact zones would have resisted a total progressive collapse. These ideas were then developed in greater detail by Jeff King and Jim Hoffman on their websites, with little attention from the mainstream media.

Eric Hufschmid's Painful Questions was the first book-length treatment of the hypothesis, and included questions about Building Seven. In 2004 this book was singled out by proponents and debunkers alike. Popular Mechanics started its investigation into this and other 9/11 conspiracy theories when Painful Questions was advertised in the New York Times and theologian David Ray Griffin listed Hufschmid's questions among the reasons to re-investigate the events of 9/11 in his book The New Pearl Harbor.

In late 2005, Steven E. Jones, a physicist then at Brigham Young University, made his own pursuit of the hypothesis public. Even before publication of the article in the 2006 book "9/11 and the American Empire: Intellectuals speak out," his interest in the hypothesis brought a measure of scientific credibility and increased media exposure to the theory. In consequence, however, Jones was placed on paid leave by his university in September 2006 for his "increasingly speculative and accusatory" statements. He left Brigham Young shortly afterwards, accepting an offer of early retirement.

The controlled demolition hypothesis and the mainstream explanations of the collapse developed alongside each other. Proponents of the controlled demolition hypothesis, for example, were among the first to question the "pancake collapse" hypothesis, in which floors progressively detached from the columns due to the force of higher floors falling on them. This theory, which constituted the mainstream consensus until the middle of 2005, was later rejected by NIST in favor of a scenario in which sagging floors remained connected to perimeter columns, pulling those columns inwards and initiating collapse. .

In its effort to understand the collapse of Building Seven, moreover, NIST claims to be currently developing "hypothetical blast scenarios" that will be of interest to proponents of controlled demolition. Likewise, Zdenek P. Bazant, who co-authored the first published analysis of the collapses of the two towers, has proposed examining data from controlled demolitions in order to better model the progressive-collapse of the towers. The controlled demolition hypothesis has been pursued mainly by experts in fields other than structural engineering and by a network of amateur investigators.

World Trade Center Seven

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

Videos that show the fall of 7 World Trade Center have become a mainstay of presentations of the controlled demolition hypothesis. This was a 47-story steel-framed skyscraper that stood across Vesey Street north of the main WTC complex. Though not hit by a plane, it collapsed at about 5:20 p.m. EDT on the evening of September 11, 2001. No steel-frame high rise had ever before collapsed because of a fire. NIST has postponed publication of its report several times, attributing the delays to reassignment of investigators to other tasks.

In addition to its being unexplained, proponents of controlled demolition often emphasize the collapse of WTC7 for two reasons. First, because it was not hit by a plane and, second, because its collapse looked even more like a bottom-to-top standard controlled demolition than the more explosive top-to-bottom collapses of the two main towers. Support for this theory comes from visually observed features of the collapse--the swift and symmetrical fall, the pulverization of what the theory supporters assume is concrete, the lateral ejection of debris from high up for large distances. They also cite an early report of molten and partly evaporated steel, which seems to indicate extremely high temperatures.

In the PBS documentary America Rebuilds, which aired in September 2002, Larry Silverstein, the owner of Building Seven and leaseholder and insurance policy holder for the remainder of the WTC Complex, recalled "I remember getting a call from the Fire Department commander, telling me they were not sure they were going to be able to contain the fire. I said, you know, “We've had such terrible loss of life, maybe the smartest thing to do is just pull it. And they [the FDNY] made that decision to pull and then 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. Many of the theories involving controlled demolition imply that the landlord Silverstein had the building(s) destroyed for the insurance money. Silverstein issued a statement that rejects this interpretation asserting that he had firefighters on his mind.

In a New York Magazine interview in March 2006, Dr S. Shyam Sunder, NIST's lead WTC disaster investigator, said "We are studying the horizontal movement east to west, internal to the structure, on the fifth to seventh floors," and then added, "but truthfully, I don’t really know. We’ve had trouble getting a handle on Building No. 7." Hugo Bachmann and Jörg Schneider, both of the Swiss Federal Institute of Technology, believe that building 7 was intentionally demolished based on video footage.

Proponents have timed the collapse at just under seven seconds. 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." This is roughly the point at which Jones begins timing the collapse, noting that his results correspond with the free, unimpeded fall of the roofline. This purported "near freefall" collapse time is a recurrent theme of the controlled demolition hypothesis.

Notable Seven World Trade Center government tenants included the CIA, Department of Defense, IRS, Secret Service and the Securities and Exchange Commission.

Main towers

The collapses of the main towers showed several similarities. While fires were still burning, the top sank into the damage area. A cloud developed around the failure as it progressed downward, and large pieces of debris fell away from the sides of the building. As the cloud reached the level of other buildings, it expanded through the streets of surrounding blocks. Both towers were completely destroyed, an event with no precedent among skyscrapers that have suffered local damage or sustained fire.

Because a detailed explanation of these collapses is available, proponents present controlled demolition, i.e., the presence of pre-planted explosives, as an alternative hypothesis that better explains the observed facts of the collapses. They emphasize the symmetry, completeness and near free-fall speed of the collapses; the reported sounds of explosions; the shooting out of debris and smoke (so-called "squibs"); and reports of molten metal.

Structural argument

The hypothesis proceeds from the assumption that without explosives to destroy the internal support structure of the WTC towers, the fall of the towers would violate the principle of conservation of momentum. Since the structure underneath provided almost no resistance to the falling upper stories, it is argued, the collapse of the towers at near free-fall speed indicates that the central core below the impact zone had lost its structural integrity. This assumption is also sometimes said to imply that if the buildings had resisted the collapse as the laws of physics predict the tops would, at worst, have tipped over, in each case falling off the remaining structure rather than through it. Since the mainstream explanation does not describe any damage to this structure (beneath the impact zone) controlled demolition is proposed as a better way to explain this lack of structural resistance.

Engineers who have investigated the collapses, however, 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, they argue, it could not ultimately have fallen into the street, leaving the rest of the building intact. Any such tilting, they argue would place such an enormous strain on the lower story (acting as a pivot) that it would collapse long before the top had sufficiently shifted its center of gravity.

The total collapses of WTC 1 and 2 have not been modeled in a way that could either confirm or refute the controlled-demolition hypothesis, in part because of an early calculation that showed that the force of the falling upper section was at least an order of magnitude beyond what the lower section could support. The NIST report therefore provided an analysis of the structural response of the building only up to the point where it says collapse was inevitable due to this enormous weight of the buildings above the damaged floors. That is, NIST did not simulate the structural response of the parts of the buildings which are of primary interest to supporters of the demolition theory. Indeed, some critics of the controlled demolition hypothesis suggest that more detailed modeling of that response might put the hypothesis to rest.

Visual evidence

Proponents often encourage their audiences to compare the video footage of the collapses of the WTC towers with footage of known controlled demolitions. They then identify what they believe are signs of controlled demolition. Among the most commonly cited are tightly focused horizontal plumes of smoke and debris being ejected from the twin towers during the collapse. The plumes appear approximately 10 stories below the area of advancing destruction and are ejected only from the centers of the towers. These plumes appear in both towers, at regular intervals, and from multiple camera angles. They are identified by proponents of controlled demolition as evidence for "squibs", i.e., exploding shaped charges intentionally destroying the structure of the buildings.

Girders of weight up to 4 tons each were found 600 feet from the WTC2. This feature is pointed out by those who endorse controlled demolition hypothesis. FEMA stated that it was the column section from WTC2 that was embedded into Bankers Trust Building 600ft away.

The mainstream theory attributes the plumes to material ejected due to the evacuation of air as the floors collapsed. In rejecting the controlled demolition hypothesis, investigators note that the failure began specifically in the damage area and progressed downward. Indeed, implosive demolitions initially sever supports at the bottom of the building to start the whole structure moving downward. Explosive charges higher in the building serve only to fragment the debris.

Recently discovered centimeter sized bone fragments found up on top of the Deutsche Bank Building, and generally an incredible degree of fragmentation of victims, contribute to an argument for controlled demolition for proponents.

Witness statements

There were a number of eyewitness accounts of explosions just prior to the start of the collapse of the towers. These are cited as evidence for controlled demolition. Witness statements are numerous, redundant and detailed. "It seemed like it was going all the way around like a belt, all these explosions," one witness said. "You see three explosions and then the whole thing coming down," said another. Many firefighters, in statements obtained by the NY Times, also testified to what they perceived as explosions.

Some claim that a BBC news story on September 11th, which appeared to be covering the collapse of WTC Building 7, is evidence of foreknowledge of the collapse of that building, given that building is visibly still standing as the reporter is explaining the collapse, approximately 23 minutes before it actually did come down. This report occurred nearly 25 minutes after firefighters had decided to evacuate Building 7 and to "to clear the area and create a collapse zone around [it]."

A few witnesses describe what they believed to be 'basement bombs'. William Rodriguez, a WTC janitor in the North Tower at that time, reported that while he was in the basement of the north tower with about 20 others a large explosion took place on Sublevel B3 actually before the plane hit. However, in his testimony before the 9/11 Commission, Rodriguez also claimed to have seen a hijacker scoping out the building some months before the attack, testimony which was not published in the report. Mike Pecoraro, a mechanical engineer who had seen the bomb attack in 1993 and was working in the sixth sub-basement of the north tower on 9/11, also gave detailed observations of what he believed to be damage from bombs. WTC construction worker Phillip Morelli described a basement explosion sound at the time of the plane impact that knocked him to the ground, although he later explained that it was most likely the freight elevators being cut loose above and hitting the ground. Some researchers suggest other possible reasons for explosions in the basements, such as explosions of electrical equipment.

Some firefighters who had reported explosions later came to a different view of what they had perceived. For example, one said, "We realized later after talking and finding out" that the ten or so "explosions" he and others had heard coming from the south tower were actually "the floors collapsing to where the plane had hit."

Critique of fire theory

Proponents of controlled demolition argue that the fires could not have been hot enough, nor burnt long enough, to significantly weaken the steel in the buildings to a point of collapse. Sometimes they refer also to examples such as NIST's 2004 fire test in which sample structures exposed to fire were shown to be "able to withstand standard fire conditions for between one and two hours" without failure.

Some have compared the heat of the fires in the twin towers and the fires' effect on steel to findings in actual fire tests carried out by steel manufacturer Corus (formerly British Steel) on unprotected steel beams in open-sided car parks. The highest recorded steel temperatures in those parks when beams were exposed to hydrocarbon-fuelled fires was 360°C, well below NIST's estimated 800°C temperature of the steel supports in the twin towers at the time of the fires.

Several studies made by NIST also showed that temperatures were relatively low. A paint study shows that neither perimeter nor core columns were exposed to temperatures exceeding 615°C for longer than 15 minutes and mostly temperatures were below 250°C. Furthermore the simulation data in the NIST report indicates that the temperature of the steel was falling at the time of collapse.

In April 2007, a gasoline fire weakened a steel reinforced bridge span to the point of collapse in the San Francisco Bay area.

Thermite hypothesis

Proponents of controlled demolition argue there was evidence of temperatures well beyond those that, by general consensus, can be attributed to the fires. It is pointed out that "molten material" streamed out of the south tower shortly before it collapsed. There were reports of "molten steel" in the pockets of the rubble. Firefighters described having seen in the rubble "molten steel running down the channels, like you were in the foundry". Moreover, World Trade Center USGS Thermal study, conducted on September 16,2001 using Airborne Visible/Infrared Imaging Spectrometer, showed hotspots in the rubble reaching temperatures greater than 1000 K (727°C, 1341°F)

Steven Jones has stated that the molten material may have been molten 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) required to melt structural steel. He takes this to be an indication that thermite might have provided the energy required to demolish the buildings. In late 2006 Jones conducted molecular analyses to ascertain the presence of explosive residues on steel samples from Ground Zero and in the released dust and says he found chemicals consistent with the presence of thermate (a mixture of thermite and other oxidizing agents used in incendiary munitions).

NIST has publicly commented 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. While it maintains that there is no evidence for controlled demolition, NIST is examining the thermite hypothesis in its ongoing investigation of 7 WTC. In the case of the towers, NIST proposed 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. The initial FEMA investigation team also found sulfur within the structural steel from 7 WTC along with indications of extremely high temperatures. Neither the FEMA study nor the NIST report identify a source for the sulfur, but NIST has since noted that sulfur is present in gypsum drywall and other construction materials used in the towers.

Dust clouds

Some have argued that the production and expansion of the enormous dust clouds that covered Manhattan after the collapses are an indication of an additional source of energy, such as explosives. They say 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 at least 10 times. NIST attributes these clouds to the ejection of air from compressed parts of the building.

Debris removal

Webster Tarpley, in particular, 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. 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. James Quintiere, Professor of Fire Protection Engineering at the University of Maryland, when criticizing NIST report, called the spoliation of the steel "a gross error". Quintere criticized the NIST report as lacking physical evidence to support its conclusions.

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." 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."

NIST recovered steel samples from both the towers but "no steel was recovered from WTC7" (NIST NCSTAR 1-3), and determined for the twin towers that "only three columns had evidence that the steel reached temperatures above 250°C... [T]here was no evidence that any of the samples had reached temperatures above 600°C." NIST however, did not generalize these results "since the examined columns represented only 3 percent of the perimeter columns and 1 percent of the core columns from the fire floors." In addition, members of the National Construction Safety Team Advisory Committee, which oversaw the NIST investigation, called into question the adequacy of the samples at their October 19-20, 2004 meeting after the metallurgical results were initially released:

Q: I have a problem with the statement that the steel collected for the investigation is adequate. If I were doing an accident reconstruction, I would’ve been looking for core columns that were hit by the aircraft. It may be okay from a research perspective. It should not be stated that it is adequate from an investigation point of view.
A: It would have been nice to have, but may have been very hard to find...

Q: ...NIST never had the opportunity to do this type of search.
A: The Structural Engineers Association of New York (SEAoNY) started collecting steel in October of 2001. NIST was a member of that team... Some steel had disappeared and was recycled. NIST took over 8 months before the investigation began. We did not have reconstruction in mind. That would have been extremely expensive for us to do... If we had the authority, we would have been more aggressive.

Q: The hypothesis is that core columns got above 600 ºC. It would be nice to have pieces of steel to support that hypothesis....

C: As John Barsom said, the [adequacy of steel] statement is not accurate. The validity of the model question from yesterday speaks to this issue. I do not believe that we have enough forensic evidence. It may be okay to establish steel quality. There was no effort by the Building Performance Study team to systematically look at the steel.

C: The use of the term “adequate” needs to be revisited. There is no core column test to support the hypothesis.

In response to concerns about the destruction of evidence, W. Gene Corley, head of the Building Performance Assessment Team on the site, stated that "The team has had full access to the scrap yards and to the site and has been able to obtain numerous samples." Corley also stated his opinion that, "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."

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?" in a book called 9/11 and the American Empire: Intellectuals Speak Out, edited by Peter Dale Scott and David Ray Griffin. Griffin, a retired professor of theology, published his own version of the hypothesis in The Hidden History of, 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 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 chapter to the Griffin and Scott volume. 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.

All these authors refer to the controlled demolition of the World Trade Center as a hypothesis in need of further investigation before it can be accepted as true. Their accounts of the hypothesis overlap in many ways, but they each offer a distinct perspective. Jones concentrates on the physical plausibility of the mainstream explanation and possible similarities to controlled demolition. While Griffin also summarizes suggestive physical features of the collapses, he adds a reading of the verbal statements that were released by the New York Fire Department in August 2005 and published by the New York Times. These constitute a substantial body of eyewitness testimony of the collapses and the events that led to them. Tarpley takes a more historical view, emphasizing expert opinions proposing controlled demolition shortly after the attacks; the behavior of government agencies (especially the New York Mayor's Office) in the handling of the WTC site; and public criticism of the mainstream investigation into the collapses. This criticism of both the motives and the methods of mainstream investigations is central to the defense of the controlled demolition hypothesis and here Ryan's contribution has become influential.

Reactions from engineers

The controlled demolition hypothesis has been unambiguously rejected by mainstream investigators and by structural engineers. Zdeněk P. Bažant, who was among the first to offer an explanation of the collapses, mentioned the controlled demolition hypothesis in passing in a 2006 paper, co-authored with Mathieu Verdure. Affirming the mainstream consensus as presented in the NIST report, Bažant and Verdure note "a few outsiders claiming a conspiracy with planted explosives" as an exception. They trace "strange ideas" about, among other things, controlled demolition, to a "mistaken impression" that safety margins in design would make the collapses impossible. While, strictly speaking, superfluous, one of the effects of a more detailed modeling of the progressive collapse, they say, could be to "dispel the myth of planted explosives". To date, however, no such detailed model has been put forward.

Other engineers, such as Thomas Eagar, have also dismissed the controlled demolition hypothesis with reference to the consensus that has formed in the engineering community about the collapses. 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."

Leslie Robertson, who helped design the Twin Towers, debated Steven Jones on a radio program in December 2006.

Brigham Young University professor D. Allan Firmage stated that: "I have studied the summary of the report by FEMA, The American Society of Civil Engineers and several other professional engineering organizations. These experts have given in detail the effects on the Towers by the impact of the commercial aircraft. I have also read Professor Jones' (referred to) 42 page unpublished report. In my understanding of structural design and the properties of structural steel I find Professor Jones' thesis that planted explosives (rather than fire from the planes) caused the collapse of the Towers, very unreliable."

Building demolition experts have also weighed in on the hypothesis, noting that demolishing buildings by implosion typically requires weeks of active and easily detectable preparation.

Popularizations

The research of proponents like Hoffman, Griffin, Jones and Tarpley has entered popular culture by a variety of means, many involving new media. A Scripps/Howard poll found that people who are most likely to endorse this hypothesis get most of their information from the Internet.

Several documentaries have also defended the controlled demolition hypothesis, including 9/11 Mysteries, Improbable Collapse, and Dylan Avery's Loose Change. A number of lectures by Hoffman, Jones and Griffin have also been made available online.

The demolition hypothesis first entered mainstream media by way of negative press coverage of "9/11 conspiracy theories" or "9/11 myths". An article in Popular Mechanics, which was later expanded into a book, also presented the hypothesis to a mainstream audience, as did the popular magazine Skeptic. Such coverage generally takes a very critical view of the hypothesis.

New York Magazine published one of the first major articles that offered a partially sympathetic take on the hypothesis. Finally, the hypothesis has also been cited by a number of celebrities, including David Lynch and Charlie Sheen, inviting much interest from the public. David Lynch on VPRO's Wereldgasten, on December 3rd 2006:

At the World Trade Center, three buildings came down, like demolitions, and two of them were hit by a plane, but the third one they said "do you want us to pull it?" and they pulled it and it looked just like the other two. Those things bother me. [...] It's just an event that has many questions and no answers.