TURN ON THE TV RIGHT NOW

[Alexis Janson]

The world trade center is falling down again!

[Quantum P.]

So I've heard. Also, why is this in ZZT General?

[Cheesecake Avenger]

Gasp! AGAIN?!

[davew27]

Sorry, I tripped over it :(

[Cheesecake Avenger]

you really have to watch where your going next time. we dont want it falling over again...

[ajc]

I never get tired of your 'Yellow Borders' avatar..

[Cheesecake Avenger]

im updateing it with more advertures soon

[ajc]

The world will be watching and waiting.

[Cheesecake Avenger]

[Shadowhero]

Is it really?

[Fungahhh]

Yes.

[nuero]

[FSFunky]

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.
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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.
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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.
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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.
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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.
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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 more straight 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.
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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.
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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.
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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.
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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.
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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.
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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.

[GreyKnight]

FSFunky has been possessed by the spirit of Wikipedia

[Alexis Janson]

Funky's post is from skepticwiki, not wikipedia. The wikipedia page on the 9/11 conspiracy is here:

http://en.wikipedia.org/wiki/9/11_Conspiracy

Here's the section on the controlled-demolition theory:

Controlled-demolition theory

The NIST report did not analyze the actual pattern of the WTC's collapse; the scope of the investigations was limited to the events leading up to the collapse: "The focus of the Investigation was on the sequence of events from the instant of aircraft impact to the initiation of collapse for each tower. [This report] includes little analysis of the structural behavior of the tower after the conditions for collapse initiation were reached and collapse became inevitable."[9] The FEMA report, some say, also did not analyze the actual pattern of the collapse. (For further information on these reports, see 'Government Inquiry' below)

Skeptics of the progressive collapse, or "pancake" theory, say that there is ample evidence that the towers collapsed due to the systematic destruction of internal supports. Jim Hoffman, a researcher and software engineer, says that the telltale signs of controlled demolition, present in the WTC collapse, are:[10]

* Radial symmetry: The Towers came straight down, blowing debris symmetrically in all directions.
* Rapid descent: The Towers came down just slightly slower than the rate of free fall in a vacuum.
* Demolition waves: The Towers were consumed by synchronized rows of confluent explosions.
* Demolition squibs: The Towers exhibited high-velocity gas ejections well below the descending rubble.
* Pulverization: The Towers' non-metallic components, such as their concrete floors, were pulverized into fine dust.
* Totality: The Towers were destroyed totally, their steel skeletons shredded into short pieces, most less than 30 feet long.
* Molten metal: A stream of liquid metal was videotaped[8] flowing out of the corner of 2 WTC moments before collapse, and eyewitnesses observed and reported pools of molten metal in all three rubble piles.

Steven E. Jones, a physics professor at Brigham Young University, and Judy Wood, a mechanical engineer at Clemson University, say that without the use of explosives to destroy the buildings' internal support structure, the fall of the towers violates conservation of momentum. [11] In addition, Dr. Jones says the angular momentum of the top of the South Tower as it began to collapse could not simply disappear, unless the center of mass of the top was somehow shattered and destroyed.[12] In addition, he says that the collapse of the towers at near free-fall speed indicates that the central core below the impact zone had lost its structural integrity and provided almost no resistance to the falling debris.

Molten metal

In addition to the characteristics of the collapse, eyewitnesses reported pools of molten metal in the rubble of 1, 2, and 7 WTC for several weeks after the collapse.[13] According to reports by FEMA[9] and NIST,[10] molten metal (visible on video [14]) dripped out of the South Tower just before it collapsed. Having analyzed the color of the molten metal, which is an indicator of its temperature, Dr. Jones believes the metal was at least 1000°C. Adherents of the official theory say the molten metal may simply be aluminum from the aircraft, which melts at about 650°C. Dr. Jones rejects this theory since molten aluminum is a poor emitter of black body radiation and thus molten aluminum appears silvery-gray under daylight conditions.[15] (The metal in the video is bright yellow.) According to Jones, the presence of molten metal at 1000°C would contradict the official story, which says that fires in the buildings reached temperatures high enough to weaken the steel, but not to melt it.

In addition to the molten metal, the initial FEMA investigation team did find unusual sulfide on parts on the structural steel in the towers and 7 WTC.[11] FEMA was unable to find the source of sulfur, and the NIST report does not mention it. Researchers including Steven Jones believe this sulfide may have been caused by the use of a thermite reaction to melt and destroy the steel within the structure. Others have suggested the sulfur originated from gypsum wallboard [12]

Thermite reactions can reach temperatures of up to 4500°F (2500°C), well beyond the temperature (approximately 1500°C) required to melt structural steel, and with the addition of sulfur can cause an eutectic reaction within such steel.[16] Such a eutectic reaction was observed at WTC and according to professors Ronald R. Biederman and Richard D. Sisson Jr. was "capable of turning a solid steel girder into Swiss cheese."[13] Thermite would also explain the presence of the aforementioned molten metal seen dripping out of the South Tower. Dr. Jones believes this metal is actually molten iron, a byproduct of the thermite reaction.[14]

Symmetry and Squibs

1, 2, and 7 WTC also fell straight down with, according to theorists, remarkable symmetry. Without explosives, they say, this symmetry would violate the second law of thermodynamics. Collapse theorists also point to photographs and videos of what they believe are demolition "squibs", which are tightly focused horizontal plumes of smoke and debris being ejected from the twin towers during the collapse. Official theorists propose that the squibs were merely the ejection of material due to the evacuation of air as the floors collapsed; the plumes, however, appear approximately 10 stories below the area of main destruction and are ejected only from the centers of the towers.[17] These plumes appear in both towers, at regular intervals, and from multiple camera angles. Researchers say the presence of these squibs indicate secondary explosive devices, activated just ahead of the collapsing material, removing the structural support and allowing total collpase. It is also believed that squibs were seen in the destruction of 7 WTC, running rapidly up the Southwest corner of the building[18]. Similarly, while a possible theory is that the 7 WTC squibs simply result from the floors collapsing, the time between the events is much too rapid to be due to gravitational acceleration.[19]

Oral History Support for Demolition

As evidence of controlled demolition, 9/11 researchers point to eyewitness descriptions of the events before the collapse of the towers which appeared consistent with explosives, such as "It seemed like it was going all the way around like a belt, all these explosions," and "You see three explosions and then the whole thing coming down," etc.[20][21]

In addition, William Rodriguez, a high profile survivor[15] was located in the basement of the North tower, when he reported a large explosion on Sublevel B3, before the plane impacted. Rodriguez escaped the building, and escorted several people to safety.

His testimony was told to the 9/11 commission, but no explanation was ever given for the explosions.

Molecular and Chemical Support for Demolition

Recently, Professor Steven Jones conducted molecular analyses to ascertain the presence of explosive residues on steel samples from Ground Zero and in the released dust [22]and indicates that chemicals consistent with thermate are present. Other environmental studies have been done on the particulate matter and dust released by the collapse (including a study by the DELTA group at UC Davis), and none have indicated the presence of explosive residue.[23] [24].

Pulverization

Software engineer Jim Hoffman suggests that gravity alone exerts too little energy to explain the pulverization of non-metallic building contents into fine powder, or to explain the pyroclastic flow-like cloud of dust which billowed down the streets of lower Manhattan in all directions[25].

Lack of Collapse Precedents

Furthermore, theorists allege the collapse of 1, 2, and 7 WTC are anomalies, since no steel high-rise building has suffered a total collapse as the result of fire before or since the 9-11 attack. The WTC towers burned for less than 102 min (1 WTC) and 56 minutes (2 WTC), during which both towers were stable after the impacts. Theorists consider the following hi-rise fires to be the most similar for comparative purposes: [26]

* 1 New York Plaza (1970) - burned for more than 6 hours, no collapse.
* First Interstate Bank (1988) - burned for 3 1/2 hours, gutted 4 floors of the 64 floor tower, no collapse.
* One Meridian Plaza (1991) - burned for 18 hours, gutted 8 floors of the 38 floor building, no collapse; later had to be demolished.
* Torre Este de Parque Central (Central Park's East Tower, Caracas, Venezuela) (2004) - burned for more than 17 hours, spread to over 26 floors, no collapse.
* The Madrid Windsor Tower (2005) - a partial collapse of some steel sections building [27], [28], while the concrete framework prevented a complete collapse [29].

Researchers say these fires are particularly relevant to WTC7, which was not struck by planes and which suffered damage only from fires and falling debris from the collapse of 1 and 2 WTC.

The Caracas Tower, First Interstate Bank [30] and 1 New York Plaza were constructed using the conventional steel girder system consisting of a grid of steel columns and trusses connecting the columns. The Windsor Tower, however, was constructed with concrete columns and a concrete core for the first 16 floors, steel girder and concrete core for the floors above that, and two additional concrete slabs to provide additional strength [31], [32].

Those attempting to debunk 9/11 researchers have compared the WTC collapses to the Ronan Point disaster [33], in which one corner of Ronan Point collapsed after a gas explosion [34]. Although Ronan Point was found to be structurally unsound (unsafe) [35] [36], the building did not totally collapse. However, 9/11 researcher Jim Hoffman has noted that the section of the Ronan Point building that collapsed were nonstructural - the short cantilever sections were supported by the building's main structure, making any comparison with the WTC towers unsound. Hoffman states, "The problem with the progressive collapse theory is that it's very difficult to actually build something that will exhibit this behavior."[37]