The 9/11 Forum

one thing i rarely see mentioned, is the lack of broken out windows in a building supposedly, "fully involved in fire".

For a person looking at videos of the fall of WTC 7, what do you think are the primary, most compelling reasons a person may strongly suspect foul play?

It is the direct perception of the way in which WTC 7 collapsed. Way too symmetrical and clean.


Is it because of the fall time? No. (Though the fall time thread is really good, the average person looking at the WTC 7 fall probably won't even understand the fall time argument, having taken only one year of physics at most.)

Is it because an adherence to some crush-up equation? No.

Is it because the size of the rubble pile? No.

Is it because of the organized, folded in nature of the rubble pile? Yes!



We must understand in the most essential terms where the MIHOP argument is coming from and why such a large number of people find it to have merit.

This is why I tried to distinguish between the most primary MIHOP arguments and more secondary arguments in the last post. It is pure speculation, I know, but I think you'll understand what I mean.

The primary arguments are not quantitative at all. They are qualitative:

They are the direct perception on the part of the viewer that the 47 story building cleanly fell with a shocking symmetry into an equally shockingly infolded compact and clean rubble pile.

This is, I believe, the center of the MIHOP WTC 7 argument.


In this light let's consider diesel.

Diesel is merely a loose explanation of the ultimate cause of the WTC 7 collapse.

It doesn't even remotely address what I suggest are the primary WTC 7 MIHOP arguments.

Within all the WTC 7 debate, we have to remember what the most central MIHOP argument is.

More importantly than the fact that WTC 7 fell is how it fell.

It is a qualitiative argument based on how the collapse looked and how incredibly compact and organized the rubble pile looked.


Neither dIesel fuel or thermal expansion can remotely explain the miraculous symmetry and cleanliness or the fall or the compact organization of the resulting rubble pile.

Diesel fuel tries to explain the cause for the collapse, but, if you think about it, fails to even address the most central issues around why people suspect foul play.

It is interesting that people who look for a natural explanation for WTC 7 are still on the subject of the fact that it fell in the first place. Notice that the present non-MIHOP arguments have not even been able to explain why the building fell. They don't even touch on the bizarre way in which it fell. The way that it fell is what really captures peoples attention.

The fact that it fell is only a secondary MIHOP argument. How and into what are the primary arguments.

Thus we see experimental and theoretical confirmation that the global collapse of a 20-story building would take at least 10 seconds to partially collapse from deliberate man-made explosive or natural seismic trauma to lower portions of its structure.

A Building 7 Collapse Conundrum:

Continuing with the question of how fast Building 7 could possibly have collapsed I wish to present here a few more thoughts on this topic. While this obviously overlaps some existing threads I hope it offers something new and specific about the theory and observational data for WTC 7 collapse times.

Let’s assume that the columns supporting a lower floor of Building 7, say floor 8, suddenly failed (by some unspecified mechanism) allowing the 39 floors above to start moving down as a solid block without any significant resistance. Eventually the 9th floor would impact the 8th floor. Let’s assume that the columns supporting the 8th floor were very strong so that the 9th floor was completely stopped by the lower part of the building.

Consider now the motion of the 9th floor. Although the floor-to-floor height in Building 7 was close to 4 meters, a freely descending floor would nonetheless have to meet significant resistance well before it had fallen the full floor height. If you think of a typical office in a modern high-rise building there is a lot of furniture, partitions, computer hardware, printers, bookshelves, filing cabinets, water coolers, etc, on more or less every floor. This office “live load” is typically about 1 meter tall and we can reasonably assume it is crushable only down to an average height of about 25 cm. Thus we see that a collapsing floor will always be decelerated over a distance of about 0.75 meters. And while a free fall drop of 4 meters takes 0.903 seconds and reaches a velocity of 8.86 m/s, our collapsing 9th floor will of necessity take longer and be moving a little more slowly than in the case of an ideal floor dropping under free fall.

In order to make a rough estimate of the motion of a collapsing floor under these circumstances let’s assume that office live loads present a constant retarding force, starting after 3 meters of free fall, that brings the floor to rest after 3.75 meters. Thus for our collapsing 9th floor we have initial free fall motion for a time of Sqrt[6/g] = 0.782 seconds, by which time the descent velocity had reached 7.67 m/s. We now need to calculate how long it would take the 9th floor to come to rest after crushing everything on the 8th floor down to a compresses mass 0.25 meters tall. Because we have assumed a constant retarding force we must have a constant deceleration, a. It follows that the stopping time is (7.67/a) seconds. We can then use the relation v^2 = 2a.s, where s is the stopping distance of 0.75 meters, to find a. Substituting appropriate values into these equations we have a = v^s/2s = (7.67)^2/1.5 = 39.2 m/s^2, or a deceleration of the 9th floor of close to 4g’s, and the stopping time of 0.196 seconds.

We need to compare this time to the time to go from 3 to 3.75 meters under free fall, which is 0.092 seconds. Hence we see that the crushing of the office live loads adds 0.104 seconds to the 9th floor collapse time. Working backwards, we find that the average acceleration over the 9th floor collapse would have been (2 x 3.75) / (0.782 + 0.196)^2 or approximately 7.84 m/s^2, which is significantly less than g.

Something I have glossed over in this analysis is the question of what happens to the floors above the 9th floor during its collapse onto the 8th floor. There are two limiting cases to consider:

(i) The upper floors sequentially loose their support columns at the instant the retarding force kicks in, (as in a controlled demolition!). For this case we can simply repeat the calculation presented above but with an initial velocity calculated from the final velocity of the upper block before retardation sets in. Based on the need to crush live loads on every floor this can only further delay the collapse, leading to a collapse acceleration well below g.

(ii) The upper floors resist further collapse as in WTC 1 & 2. Here we need to consider the energy to collapse one floor and this would certainly be at least 0.5 GJ. In this case the overall collapse acceleration is going to be in the 5 – 7 m/s^2 range or significantly less than g.

Thus the conundrum I set readers of this thread is to explain the physics behind measured WTC 7 collapse accelerations “close to g”, namely in the range 8.8 to 9.8 m/s^2.

I'm satisfied that the claim of freefall is majority false, at least as a gross assessment, if you can appreciate the fuzzy logic of that. I've got the tweezers and microscope out, more so than anyone prior of which I'm aware, and the trail disappears into legitimate ambiguity.

I'm already aware that the rate is not exactly free-fall, and it's not exactly 2.25s either. Varies all the time, of course.

Does any 'official' narrative have any explanation for this behaviour ?