The first step in beginning to analyse and critique the official account of the tower collapses is to understand the way they were built. Each tower was like a giant steel cage made of 236 steel perimeter box columns (35 cm x 35 cm), joined together with steel spandrels at regular intervals. The characteristic vertical lines on the fours sides of the towers were simply these steel columns, covered with aluminium. Running up the centre of the towers were 47 even larger steel box columns (36 x 90 cm or 55 x 135 cm), which were cross braced. The steel plate used in the columns was 100 mm thick at the base, and got thinner towards the top, where it had to carry less load. At each floor, the outer columns were connected to the core columns with steel trusses, bolted to welded steel brackets on the columns (below right). The trusses were covered with corrugated metal sheet, and a layer of concrete was poured on top. Thus each tower was essentially a massive steel structure — steel perimeter, steel core and steel floors — with concrete only serving to distribute the weight on each floor. "What struck us – guys like Warren Jennings and myself, who have spent basically all our lives in the scrap business – we’d never seen steel this heavy, this huge, this massive. It was just unbelievable." - Michael Henderson, General Manager, Marine Terminals, Metal Management NE, quoted in "Stepping Through the Ashes" (p. 93) Below left: WTC core columns ready for recycling (top), and the rubble at 'ground zero' was mostly steel column segments (bottom).

2.1. Misinformation about the structure of the towers

a) Look at the graphic (left) published by the BBC on September 13, 2001, which supposedly illustrates the structure of each tower, and compare it to the above description and images. b) The 9/11 Commission Report, while acknowledging the perimeter columns, makes the following (under)statement about the tower cores: "The interior core of the buildings was a hollow steel shaft, in which elevators and stairwells were grouped." (p. 541). c) The PBS/NOVA documentary, "Why the Towers Fell" (2002), displays the perimeter and core columns waving like reeds in the wind (in the absence of the floor joists), completely ignoring the extensive cross bracing.

2.2. Claims that the towers were not designed to cope with this kind of event

Consider this comment by Frank A. DeMartini (from an interview 8 months prior to 9/11):

Are we really expected to believe the WTC designers forgot about the small matter of the fuel load? A 767 is not very different in size and weight to a 707, and the two flights that hit the towers would have been carrying far less than a full fuel payload (as they were transcontinental flights). The government-sponsored investigations later admit that the fuel played no major role other than to ignite office contents over a widespread area. The fuel itself burned up too quickly to have a major impact on the steel.

This leads into the next piece of misinformation...

2.3. Claims that the fires were 'raging infernos'

There has been a lot of talk about extremely high intensity fires in the WTC towers. But this would appear to be exaggerated. Once the initial fireball had dispersed after a matter of seconds, there was a lot of smoke, but no evidence of extremely hot fires completely engulfing 4-5 entire floors as we have been led to believe.

Below left: the towers viewed from the north. The north tower was hit from this side, the south tower was hit from the south (opposite) side. Below right: the north tower from the north again, but showing more of the east face.
Bottom right: compare the tower fires with the fire in the Windsor tower in Madrid in February 2005, which burned for almost 24 hours.

As FEMA freely admitted, the jet fuel would have burned off in minutes at most. All that was burning after this time was standard office furnishings.

2.4. Claims that collapse of the buildings was inevitable

We beg to differ. There were no signs that the buildings were in danger of collapsing following the impacts. Only about 15% of the perimeter columns were severely damaged. It is hard to believe that more then a handful of the 47 core columns could have been severely damaged by the predominantly lightweight aircraft structures. It has been reported that the steel structure of each tower was six times the strength needed to handle the predicted extreme load conditions. The jet fuel fireballs, while impressive, were short lived. The ensuing fires were no different to several other office fires that have been witnessed.

There is also no evidence that the fire fighters expected the towers to collapse. They were attempting to put out the fires at the time, and were taken completely by surprise. The initial advice given to occupants was to stay in the buildings.

To say the collapses were inevitable when they were completely unprecedented seems to be being 'wise' after the event.

The combined effect of this early misinformation (such as the BBC claim that jet fuel melted the steel) was to reassure the general public — who were shocked by the sudden and explosive collapses — that there was a rational explanation. Later investigations and reports have tended to present the information more accurately. But the early misinformation was significant in guiding our general perceptions of the event down the officially sanctioned path.

3. The 'investigations'

There have been two official investigations into the WTC collapses. The first was conducted by FEMA (the Federal Emergency Management Agency) with assistance from the American Society of Civil Engineers (ACSE). The second was conducted by NIST (the National Institute of Standards and Technology).

3.1. The FEMA investigation

This initial investigation was described as a 'half-baked farce' by the chief editor of Fire Engineering magazine. It operated on a shoe-string budget with panel members working voluntarily in their spare time. It had no access to the site for the first 25 days after the event, and then only limited access thereafter. It had no authority to stop critical evidence being removed from the site. The Port Authority delayed giving the panel the blueprints for the towers for three months and required a legal indemnity to be signed. This information can be confirmed from the sources below (show/hide):

3.2. The NIST investigation

NIST had a much larger budget and spent over three years doing its investigation, but it started almost a year after the event. NIST was hampered by the same lack of access to physical evidence as the FEMA investigation, but probably more so, given their much later start.

NIST's approach was to base their investigation on photographic and video evidence, simulations (including actual fire modelling), and computer models. However, NIST did have access to some samples of steel identified as originating from the tower impact zones. So what did the only available physical evidence reveal about the intensity of the fires in the fire zones?

To summarise, nine samples from WTC 2 were from the fire floors, but had not been directly exposed to fire. Only three WTC 1 perimeter colums out of the 16 represented by samples had been heated above 250 C. The two core column samples that could be analysed had not been heated above 250 C. The metallographic analysis showed that none of the samples had been heated above 600 C as an absolute upper limit (but did not necessarily indicate that anything even approaching this temperature was reached).

The samples available for NIST's investigation were such a small percentage of the relevant steel that NIST, understandably, 'did not generalize these results'. How much faith can we have in a fire investigation that had almost no acces to the physical evidence, especially when the little physical material it did have seems to be at odds with its basic findings? How reliable were NIST's models? This is what Physics Professor, Steven E Jones, had to say about them:

4. The theories

Several theories have been put forward which attempt to explain how fire and impact damage alone caused the twin towers to collapse. It is important to remember these are only theories. No-one knows how much damage was done to the the core columns, how much fire insulation was knocked off by the impacts, or what temperatures the steel actually reached on the floors affected by fire.

Most significantly, none of the "experts" proposing these theories had access to the site immediately after the collapses to draw conclusions from the rubble and the final state of the towers. Access to the site was heavily restricted and even taking photos was strictly prohibited (show/hide quote): :

4.1. Pancake (floor) collapse

One of the most prevalent theories in the months following 9/11 was the "pancake" collapse theory, put forward by Eagar and Musso (among others):

Above left: Eager & Musso's diagram of a tower floor joist. Above right: construction photograph showing the outer edge of a joist.

There are several weaknesses with this theory:

1. It is pure speculation that the collapse of the floor joists would cause or allow the perimeter columns to 'bow outward'. Each column had its own rigid box structure that would have resisted bending, and the 236 columns were also fixed into a rigid 'tubular' structure by interconnecting steel spandrels.

2. No mention is made of the 47 massive core columns. While it might be conceivable, under very extreme fire conditions, that the floor joists/trusses on one or more floors could collapse, this would have had very little impact on either the core columns or perimeter columns.

3. Eagar & Musso speak of "roughly 45,000 t of ten floors (or more) above crashing down on these angle clips". But these 45,000 t would have continued to be supported by the core and perimeter columns.

The essence of this theory is that the first point of failure was one or more floors collapsing. The central hypothesis (weak 'angle clips') stands in complete contradiction to the final NIST report, which requires these 'angle clips' to be strong enough to cause the outer box columns to be pulled in.

Left: A model of the 'pancake collapse' used in the PBS/NOVA documentary, "Why the Towers Fell" (2002). Note that the perimeter columns are completely absent from this visual model. The core columns, while shown, are also ignored (they would have been left standing, supported by internal bracing and their own independent floor structures).

Thus Eagar & Musso/NOVA contradict NIST and vice-versa. At least one party must be wrong, and perhaps they both are. We cannot simply trust 'the experts' to explain what happened, we must weigh their arguments.

4.2. Column failure

NIST's alternative to the "floor collapse" theory is summed up below:

NIST does not model or explain in detail how the collapse would have progressed from this initial failure point to cause the complete disintegration of each building in a matter of seconds, but the basic idea is as follows:

5. The impossible collapses

There is a certain intuitive appeal to the 'pile driver' hypothesis. Apart from the simplistic floor 'pancake' explanation (which simply ignored the columns), all of the (non-demolition) collapse theories are dependent on the 'pile driver' mechanism. Yet there are several problems with it.

5.1. Too much 'work', too little energy

The towers were approximately 415 m tall. Using the formula, y=½gt², where y=415m and g=9.8 ms^-2, we can calulate the time, t, it would take for a dense object to fall from the top of the tower to the street level. The result is t=9.2 seconds.

NIST reports the time of the collapses to be 9 seconds for WTC 2 (the south tower) and 11 seconds for WTC 1. i.e. the south tower basically collapsed at free-fall speed, and the north tower just slightly slower.

Why is this a problem? Well, in the absence of any other source of energy (such as explosives), the only available energy is the gravitational potential energy (GPE) of the elevated structure. This energy has to work very hard. It pulverises and ejects virtually all the concrete, creating a massive pyroclastic flow. It also fractures all the steel box columns into short lengths and ejects them laterally at high speed. It seems doubtful that ALL of the entire available energy would have been adequate to achieve these effects. Yet after doing all of this 'work', there is still enough GPE left over (100 %) to accelerate the mass towards the ground at free-fall speed (in the case of WTC 2). In other words, the GPE appears to be being used twice over (at least). Even aside from all the destructive 'work' listed above, the inertia of the lower floors alone would be enough to prevent the falling mass from maintaining free fall speed. As each new floor is hit, the existing kinetic energy has to be 'shared' across the new, larger mass, leading to a drop in velocity. Left: The south tower collapses. Click to see the north tower.

Above: the remains of the north tower, looking across the plaza from the east with the World Financial Center buildings in the background and WTC 5 & 6 on the right. Perimeter columns are still standing on the north-east corner. Taken by John Botte fairly soon after the collapses. Note the WTC plaza "sphere" in the middle of the picture as a reference point. Click on the image to enlarge.

5.2. Where is the 'pile driver' when the dust settles?

In reality, there simply is no 'pile driver'. Most of the top section disintegrates before the collapse 'progresses' to the lower section. It is completely unrealistic to believe that around 13% of the structure (in the case of WTC 1) would be able to crush the lower 87% while itself remaining intact. The steel at the base was 16 times as thick as it was at the top of each tower. It is one thing to believe that a solid 50,000 tonne 'hammer' could crush the underlying structure, but it is something else to believe that a loose jumble of debris could have done so. It's like the difference between someone dropping a 20 kg bag of rice onto your head, or pouring it out. Furthermore, the concrete was pulverised and ejected, and about 80% of the steel was also ejected outside each tower base, so very little mass/debris actually fell directly onto the lower structure. And only a small proportion of this mass/debris would actually have struck the columns, since they only accounted for a minor percentage of the surface area.

At the base of each tower, the columns were strong enough to bear the static load of the entire 500,000 tonne structure. What kind of 'pile driver' do we see resting on them at the end of the collapse? Basically none. The building site is just a wide debris field of steel column segments and other shredded building materials/contents. There is no 'pile driver' resting on the bases of the columns. It literally looks like a bomb site.

Above: the remains of the north and south towers (footprints marked). The WTC plaza sphere has also been circled. Compare with the black and white image above. Click on the image to enlarge or click here to see more context (JPEG 3066 x 1950 pixels, 1.8 Mb), including WTC7.

Below: view of the rubble from the Bankers Trust building, with the south tower remains in the foreground and the north tower in the background. This photo may have been taken several days after the collapses, but note that all the lifting machinery is still confined to edge of the 'pile', so no large pieces of debris can have been removed from the tower areas at this stage.

6. The controlled-demolition hypothesis

If the explanation we have been given is inadequate (i.e. that fire and impact damage alone caused the collapses), what alternatives are there? We believe the explanation that best fits the observed phenomena and all the available evidence is that the buildings were deliberately demolished using a combination of thermite/thermate or cutting charges and high explosives.

NIST rejected this hypothesis for the following reasons:

NIST basically raises two objections which we will respond to below.

6.1. The collapses initiated at the impact sites

We concede that the collapse of each tower could not be described as a "classic" controlled demolition (i.e. an implosion initiated at the base). The collapse of WTC building seven was a 'classic demolition', swept under the carpet and largely unreported, a footnote to 9/11. But the collapse of the towers was the 'showpiece' of what we believe was a false flag operation, designed to be deceptive. If explosives were used to bring down the towers, as we claim, the people who planned the operation obviously tried to conceal this fact by initiating the collapses close to the impact sites. What appears to happen is that the top section of each tower (above the impact zone) is imploded just like a classic demolition. Then, just before this process completes, a rapid series of massive explosions destroys each floor from the impact site down, in succession. Left: the south tower begins to collapse. Click for another angle.

Watch the collapse of the south tower in this mpeg video (2 Mb), and note that over half the top section can be seen to implode from the base, before dust obscures what is happening. If you cannot see this in the video, look at the still frames. Using the spire as a reference point, you can see that the top section of the building (above the spire) reduces in height by about 60% before the lower section begins to disintegrate. Note also that the large top section tilts alarmingly. If this section had not been imploded from the base it would have tipped right off.

6.2. Corrobarating evidence

Is there really no 'corrobarating evidence', as NIST claims? William Rodriguez reports a massive explosion in the basement of WTC 1 just prior to the first plane impact, and multiple media accounts from the day reported 'secondary explosions' (show/hide):

In his paper, 'Why Indeed Did the WTC Buildings Completely Collapse?' (PDF, 4.8 Mb), Dr. Steven E Jones (a physicist) presents "thirteen reasons to challenge the government-sponsored reports and investigate the controlled-demolition hypothesis" (p. 4ff). Two of the most striking points he mentions are the presence of large quantities of molten iron in the bases of all three buildings, weeks after the collapses, and the red hot molten metal that can be seen pouring from the south tower just prior to collapse (from the region at which collapse initiates).

Play the video below to see and hear Prof. Jones discussing these two points, with supporting video and images. Right click here to download the wmv file instead (6 Mb).

Videos of molten metal pouring from south tower just prior to collapse: YouTube, Google video (same).

The image above (right) is taken from page 23 of Eric Hufschmid's "Painful Questions". We believe it shows that at least one of the WTC core columns has been sliced at 45 degrees, using thermite or thermate. Some people object that the clean up crews may have cut the steel using an oxy-acetylane torch or similar device, but why cut at 45 degrees? It makes the cut around 40% longer (and hence takes more time), and leaves the steel in a more hazardous and awkward shape. If you look closely you can see that the two left corners were not cut. We believe that a slot device containing thermite may have been attached to the column, and that the thermite was ignited prior to collapse to cut and weaken the column by about 90%. The collapse was then initiated using explosives, which shattered the remaining 10% of the steel, leaving the columns in convenient lengths ready for removal. A 45 degree cut is the optimal angle for ensuring collapse (a horizontal cut would allow the top section to rest or jam on the bottom section). This type of preparation is referred to by Tim Wilkinson (as a reason to reject the demolition hypothesis):

7. Firefighter oral histories

On 12 August 2005, almost four years after 9/11, more than 12,000 pages of oral histories from firefighters, paramedics, and emergency workers were finally released after an extended FOIA legal battle. They have been published by the New York Times.

Graeme MacQueen has analysed the complete corpus of oral histories for the Journal of 9/11 Studies and found that 118 of the 503 witnesses (23 %) explicitly mention explosions in their accounts of the collapse. While only ten witnesses explicitly refer to the collapses in a way that supports non-explosive collapse - see article.

We present interesting extracts below in which firefighters talk about explosions, flashes of light, noises like fireworks going off, etc. Please note two things:

1. Many of the firefighters have reinterpreted their experiences based on what they were later told about the collapses. The interesting thing is not their reinterpretations, but their first impressions.

2. Even this material has been censored. There are whole paragraphs blacked out in some documents. What was said that was even more damning to the official 9/11 account?