The Science of 9/11

Most people presenting evidence about 9/11 start by showing the collapse of building 7 (WTC 7). They start with this building because it is obvious that its collapse looks exactly like a controlled demolition. We will come to WTC 7 later, but first we will examine the NIST report on the collapse of the north tower, WTC 1. If it can be shown that the NIST report cannot be relied upon, it will make it easier to look seriously at the evidence for alternative explanations for the collapses.

[Before proceeding, note that there is a preamble to the Introduction which you may have missed, as it is not very obvious in the menu. Click on the Case button itself to find it.]

Propositions rest on a foundation. If the foundation is unsound the whole structure based upon it will be suspect. What do we find when we study the NIST report?

Most people are unaware that the NIST report does not cover the actual collapse of the towers, even though that is the task NIST was charged to perform. The report goes into great detail about the plane impacts and fires but stops short at the point where it claims the towers were “poised for collapse”. For the collapse itself NIST relies on a paper by Bazant and Zhou. This was adopted as the foundation of the NIST report. The paper was submitted for publication only two days after 9/11, which is astonishingly fast for a scientific paper and hence extremely suspicious. In a similar vein we note that the very large Patriot act was presented to the US congress very soon after 9/11 and the invasion of Afghanistan also commenced with such alacrity that one suspects the plans had already been drawn up.

The paper by Bazant and Xhou, Why did the World Trade Center Collapse? – Simple Analysis, purports to be a scientific explanation of the collapse of the towers. It has been updated since its original publication but the essence of their explanation remains the same, as follows:

1. The airplane impact damages some columns and knocks off some insulation.
2. The jet fuel helps to ignite office materials and the resulting fires heat the steel columns to about 800 deg C in the region where the insulation was damaged.
3. The loss of strength due to the high temperature allows the columns in that region to buckle.
4. The top of the building falls as a rigid body, acquiring a large amount of kinetic energy.
5. The impact of the falling block is more than sufficient to destroy the supports of the top of the lower, unheated, undamaged section of the building.
6. The mass of the falling block is augmented by the addition of the impacted material and the whole mass falls on the next floor, destroying it also, “and the series of impacts and failures proceeds all the way down”.

Only in stage 3 of this list has NIST introduced anything of its own. NIST claims that sagging of the floor trusses pulled the outer columns inward and thus started the buckling of the columns. They attempted to validate this theory by subjecting floor trusses to furnace tests. Unfortunately for NIST these tests showed that the trusses would not have sagged sufficiently to have had this effect. This theory can also be disproved by examination of the videos, which show that the antenna on the roof dropped before the edges of the roof. As the antenna was directly supported by the core columns, this proved that the core columns failed before the wall columns. It also proves that the hat truss, which connected the core to the wall columns, was severed at the outset.

Figure 1 in the paper by Bazant and Zhou, linked above, illustrates their concept of the collapse process very well. We see the top block falling through the weakened section, then continuing to fall, destroying the lower portion of the building. In particular, notice stage 5 of the collapse where the diagram shows that the top block retains its size and shape undamaged as it plows through the lower portion. It seems plausible enough and the complexity of the paper, despite its name, suggests that each step has been proved feasible.

Before we go on to study the videos, let us consider some practical and theoretical aspects of the hypothesis set out above and devise some questions to ask.

1. Is there any evidence that the columns reached 800 deg C?
2. If the collapse was started by columns getting too hot, would we not see some initial slow, sagging movement?
3. It is crucial to the NIST/Bazant hypothesis that the falling block retains its structure so that its kinetic energy can be delivered to the lower section. Is that what the videos show?
4. Can we detect any hesitation in the motion of the falling block as it impacts the lower section?

NIST examined samples of steel, including samples which were taken from the fire damaged area. They found only about 2% had experienced temperatures above 250 deg C. At this temperature collapse initiation would have been impossible as the steel would have had nearly all its original strength, and the buildings were designed with ample safety margins.

Careful study of the motion of the roof of WTC 1 shows that it commenced its downward acceleration with no apparent initial slow movement, as has been shown by several authors, for example David Chandler. The acceleration was uniform at least until hidden by dust.

Let us now look at the way the building behaved.

First we will look at some stills. Here is the building just prior to collapse. Notice that there is much smoke streaming through windows but no evidence of intense fire. If the columns were at 800 deg C, as claimed, they would be bright red-hot, but they are not.

As the perimeter columns and the core columns would hold up the roof by themselves, not only the core but also the outside of the building would have to be red hot for collapse to be initiated.

Copious smoke indicates oxygen-starved fires, which would be burning at the low end of the temperature range for fuel fires. Updrafts improve the oxygen supply and raise the temperature of a fire, but the gentle sideways drift of the smoke shows that no updraft has developed, which in turn indicates that the floors are still intact. When designing buildings, architects avoid openings in floors specifically to prevent updrafts if fire occurs. The design here appears to have been successful.

One second later the roof has dropped a short distance and we can clearly see a horizontal line of dust projecting from the building on both visible faces. The sudden acceleration and the symmetry are indications that the columns have been simultaneously severed, and the line of dust suggests that explosives are the cause.

In the next frame we begin to see that the top block is shrinking. Somewhere within its height it is giving way. Recalling that the top was supposed to be falling as a block, acting as a hammer on the lower section, this is a surprise.

In the following frame, at 2.6 seconds, the last frame in which we can properly discern the lower portion, we see that it has not yet moved and the top block is about half its original height.

It is clear that the top block, far from being a rigid hammer, is disintegrating and cannot possibly provide the impact which Bazant and Zhou have calculated. There is now a mass of fragmented material falling, which can deliver many very small blows but we can predict that it will be unable to deliver a blow representing its total mass.

This prediction is proved to be true. If the top block were to deliver significant energy through impact to the lower portion of the building, the energy consumed would result in a reduction in its acceleration. No such reduction can be detected, as shown in the paper by MacQeen and Szamboti, The Missing Jolt.

We can now summarize the answers to our questions. We have seen that the steel does not appear to be anywhere near hot enough to collapse; there is no sagging at the start of collapse, as would be expected if the steel softened; the top block does not fall as a hammer but disintegrates; and finally there is no sign of the jolt which must occur if energy is delivered to the lower portion of the building.

The only reasonable conclusion is that the collapse was initiated in the top block by explosives and that the destruction of the lower portion of the building was started a little later, also by explosives, so that it would fall away and allow the debris from the top portion to continue its downward acceleration.

The collapse was unusual in that it was conducted from the top down, and thus conveyed the impression that it was caused by plane damage and fire. This is discussed in the Twin Towers page.

It is clear the the foundation of the NIST report, the Bazant and Zhou theory, is false. Even with the attempted embellishment of sagging floors it is still false. We can now see why the NIST authors did not carry their simulation right through the collapse. If they had done so they would have demonstrated that collapse was impossible.

Others have demonstrated that collapse would not have occurred even if the steel in the plane-damaged region did suddenly fail. The first to do so was Gordon Ross in his paper Momentum Transfer Analysis of the Upper Storeys of WTC 1.

Having seen that it must be unsafe to place trust in the NIST report, the time is right to examine evidence for the alternative explanation that explosives were used in controlled demolitions. There are two more sub-pages to this page, found by hovering over “The Case” in the menu above. These deal with WTC 7 and the Twin Towers.

There are also a large number of papers which investigate features of the collapses. The page titled Papers lists many of these. Two of these papers deal with the other source of evidence which is in public hands: the dust samples which a number of people collected.

If anyone reading this has retained a sample of this dust please let the author know. It is very valuable as it could provide other researchers with the opportunity to independently confirm the findings.