Email with questions about the tower collapses
from someone new to these issues, with my response

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May 18, 2008

Hi Mark,

I'm new to this so-called 9/11 conspiracy theory, but I've heard your name batted around and seen a few videos of you coherently arguing your side, so I've come to gather that you're one of the lead 'debunkers'.  I spotted your e-mail address after reading your paper on William Rodriguez and his varying stories, and figured you'd probably be one of the best people to approach for the 'debunking' side of the story.  I also found that you were very respectful to Rodriguez in your paper (which seems to be quite rare in the debunking community!), despite having issues with his statements, and I really appreciate that.

I've looked at so much 9/11 related stuff over the past few months and it didn't take me long to come to the conclusion that it was an inside job.  Though I have found many claims made by 'truthers' to be false, like with William Rodriguez as you have shown.  I think in most cases something has been stated along the way that is picked up by a 'truther' and passed on and on so people believe it as fact without checking up on it.  So I know there are a lot of misinformed people in the truth movement, however, I don't think everyone in the movement is wrong on all their facts.

My problem is regarding the collapse of the towers, which for me is all that's needed to show there's been complicity from within the US, the rest can be debated endlessly.  I've contacted a few debunkers on this issue, and had no response from any as yet, so I was hoping you could either direct me to a good site/paper by a debunker or could take the time to get back to me explaining the debunker version of the collapses.  I really cannot think of any way this can be explained without the use of explosives.  I understand that some truthers quote shorter collapse times than actually took place, and some say things like 'they fell into their footprints', which they clearly didn't.  But this doesn't mean that the theory of controlled demolition is false, it just means that some people are misinformed on the facts.  But the crucial point is that they fell extremely quickly.

See, I don't think you have to be a physicist to wonder how the weight of the smaller upper section of the tower can drive through the larger lower section, all the way to the ground.  There would be massive resistance from the lower section which should slow it and stop it in its tracks before it gets anywhere near ground level.  The top might be expected to drop for a while, slow and then settle, or possibly topple.  Instead, there is no slowing, and in fact it seems to accelerate as it progresses, which, whether or not it's near freefall speed, goes against the laws of physics.  It implies that the top section is falling, rather than pushing - in any case, certainly not maintaining much pressure on the lower section.  Also, we see the top sections in both cases breaking up very early on in the collapse, and a large amount of material and dust thrown outward, which means there's even less force being exerted from above onto the building below to drive the collapse, so I don't see any reason for the building to collapse at all beyond the early stages, never mind completely.  For the same reason it should certainly slow down.  I just can't see how anyone could get round that with any sort of natural collapse explanation.

It's been described as pancake collapse, which does not fit well with what we actually observe.  Of course, there would still be that resistance, and there are no stacks of floors left in the footprint at the end of the collapse, all of the material has been ejected outwards over an extremely large area.  Even if the concrete and the interior materials had been smashed into dust with the impact of floors dropping, we would be left with a pile of intact (or near enough) steel floor assemblies where the building stood.  These steel floor grids are smashed into pieces and spread far and wide, and virtually no material is left in the footprints compared with what's outside.  For the building to be driven down with a great weight, that mass must be left inside the building perimeter at the end, perhaps spilling over, but certainly a greater height should be left inside than outside.  This mass should also be quite cohesive and clumped together, as it worked as one to push the building apart, all the way down.  However, the material is dispersed all over in relatively small bits and pieces, virtually levelled.

There's many more details which implies the use of explosives.  I wont question those at the moment because I really want to strip this back and get to the core of things, and a long list of bits and pieces of evidence gets in the way, and no doubt there can be alternative explanations for some of those.  However, when you add those, on top of the bizarre, apparently impossible, collapses, as far as I can see it can only lead to controlled demolition as an explanation.  This is central to the whole argument of inside job, and even if truthers have their facts mixed up on a million other pieces of evidence it doesn't matter, so long as there is not a more satisfactory explanation of a way in which this could occur naturally.  I really don't see how it can.

This is why I'm asking you, as seemingly one of the more intelligent and reasonable debunkers, if you could try to explain this from your point of view.  I know that this is not your job, and perhaps you get fed-up of having to counter all the points put forward by truthers, but I would very much appreciate your thoughts on this, or a direction of where to go to get an alternative answer.  I'm not a militant truther, I don't believe all the facts I hear without question, and I don't associate myself with any one 'conspiracy theory'.  I truly am looking for the truth, and my ideas of what happened that day are not rigid but change with all the new information I find.  I respect much of the work that people like yourself do to correct the misinformation that's out there (as much as I respect the truthers in their mission) and it's helped me to gain a more accurate understanding of events.  I think as far as there are militant truthers who are rigid in their beliefs, there are also militant debunkers who are equally stubborn.  I hope that you're not in that category, and will look seriously at this issue.

I would really appreciate it if you could take the time to think about the points I've made, watch the collapses, and think about how these could occur in a natural scenario.  If you could explain these collapses in any other way I would be grateful to hear your explanation.  But if you find difficulty in doing that, I hope that you will honestly consider the explosives theory, and how that fits in with what's seen during the collapses.  Of course, it's easy to say, 'well there's no way that anyone could rig up those buildings without it being known', or, 'it would take too many people to be in on it', and I have to agree that it's hard to understand how they could do it, but I believe they did.  I guess all that would be required would be to blow them to pieces, so the rigging could be more rushed and haphazard than your typical demolition.  I really don't know, but those questions don't need to be answered initially, nor any other regarding planes, or the hijacking, or the Pentagon.  Just the question, 'were they blown up?'

As I've said, I know that truthers can argue many points which have no basis or are just simply wrong, which makes it frustrating and easy to dismiss the whole truth movement as nothing more than a bunch of raving conspiracy theorists, but on the issue of explosives in the towers, I do think they're correct.  This is very important, because if they are correct there are great problems in your country, and it must be found out who was involved, and they must be removed from their positions as quickly as possible.

I appreciate you taking the time to read this, and I do hope you'll respond, regardless of what that response is.  Thanks again for your work, and all the best,

Jill

***

My Response:

Hi, Jill.

Thanks for your kind words and your thoughtful email.

I assume you've seen my website. I think you've done a wise thing to focus on the basics, rather than get bogged down with details. With that in mind, I'll give you some reading (and viewing) recommendations that start with basic explanations for the layman and progress to detailed and more technical explanations, if you should want to get deeper into this down the road.

Your belief that the towers should not have collapsed to the ground is a common one and is based on a misunderstanding of how the buildings were constructed and of physics. The question is not whether a smaller mass can destroy a larger one but whether the floor immediately beneath the collapse initiation zone in the towers could support the weight of the descending mass above.

First, here is a simplified explanation of how things got to that point. What started the tower collapses was fire that heated the long-span floor trusses on multiple floors of the south side of the north tower and the east side of the south tower. These were not the sides where the planes hit, but were where the fires were most severe.

Those trusses and the floors they supported sagged, pulling inward on the exterior columns, which were not designed for that kind of load. The exterior columns in the fire areas were quite thin and were merely bolted together: fine for an axial gravity load but terrible for a horizontal load. These columns bowed in progressively. This bowing process can be clearly seen in photographs and videos. When those columns could no longer support the weight above, they buckled, causing the top to lean in that direction. Unable to redistribute the load from the failed wall, adjacent walls quickly buckled, progressing around the building in one to two seconds. Keep in mind that gravity doesn't wait around like in the cartoons, and that all buildings are fighting like hell at all times to not be pulled into the center of the earth.

Many of the exterior columns where the planes hit had been severed, along with impact and heat damage to numerous core columns, which reduced the building's ability to redistribute loads. On the top of each tower was a hat truss, a network of steel beams that locked the four exterior walls together and added rigidity to the top of the building. Combined with the intact floors above the collapse initiation zones, this allowed the tops of the towers to lean, twist, and descend as a unit.

It's important to note that this was not the early leading hypothesis of what caused the collapses. FEMA/ASCE investigators initially thought that the collapses started because the connections between the floor trusses and the columns gave way, leading to "pancaking" as one floor tore loose and crashed into the one below. Theirs was a preliminary investigation, and a far more thorough investigation by NIST showed conclusively that the initial hypothesis was wrong. This is how science is done, and it disproves the conspiracist claim that the engineers were acting in accordance with some government playbook. Subsequent independent investigations by world-renowned engineering and failure analysis firms confirm that the collapses began with the inward buckling of the exterior walls.

So now we've got the whole top of the building moving downwards, while leaning and twisting. What's going to arrest its downward progress? Below is not a monolithic structure, but thousands of interconnected pieces that are designed to work together as an intact unit, starting with the floor below the collapse zone. Here's where your thinking is off, Jill. The top of the building doesn't have to crash through the whole lower structure. It only has to break through one floor at a time by defeating that floor's weakest points: the floor-column connections. And each time it breaks through a floor, it picks up additional mass and momentum, which makes the progress through the next floor easier.

Once the first floor below the collapse zone was destroyed, there was nothing that could prevent the falling mass from reaching the ground. But was there enough energy in the mass above to destroy that first floor? Yes, easily.

First reading recommendation: the second NIST FAQ about the collapse of the towers, December, 2007. Refer to questions 1 and 2:

1.  Was there enough gravitational energy present in the World Trade Center Towers to cause the collapse of the intact floors below the impact floors?  Why was the collapse of WTC 1 and 2 not arrested by the intact structure below the floors where columns first began to buckle?

2.  Were the basic principles of conservation of momentum and energy satisfied in NIST's analysis of the structural response of the towers to the aircraft impact and the fires?

NIST's simplified analysis above is quite conservative. That is, it makes assumptions that are grossly in favor of collapse prevention, the largest of which is that the weight impacting the floor below is uniformly distributed, so that all the floor-column connections are taking the strain evenly and equally.
 
You may also want to review the answer to question 10, since it's an issue often raised as a strawman argument by truthers:

10.  Why didn't NIST fully model the collapse initiation and propagation of WTC Towers?

At some point you'll probably also want to review NIST's first FAQ, from August, 2006, since it's also based largely on truther questions. The answers in these FAQs are written for the layman.

Keep in mind that Leslie Robertson, the structural engineer who designed the towers and whose reputation is attached to them, agrees with these findings and thinks the idea that explosives were used is preposterous.

But is there any evidence that explosives were involved in the collapses? No, and there is definitive proof that they were not involved, in the lack of detonations and the effects they would cause on the surroundings and on the steel. To see exactly what I mean, and how the "best" of the leading truthers engage in deception to try to hide this fact, please see my video "World Trade Center Not a Demolition."

For a much more detailed look at these issues, I recommend "On Debunking 9/11 Debunking." NASA scientist Ryan Mackey's comprehensive critique of David Ray Griffin's claims about the collapse of the World Trade Center buildings, which again is written for the layman. -pdf or doc file.

More detailed yet, but still written for the layman, is chapter 1 of the NIST report on the collapse of the Twin Towers (pdf), which is a summary of the other 9,750 pages in the report.

The collapse of the Twin Towers is studied and taught in engineering schools worldwide. You'll find a year's worth of technical reading, peer-reviewed engineering papers, conference papers, and writings about the collapses by experts and knowledgeable amateurs in the structural engineering and fire protection engineering pages of my site.

Eyewitness accounts of the deteriorating structural state of the towers and their expected collapse are here.

You may be interested to know that several experts have conducted studies that, although less thorough in general than NIST's, examined some issues that NIST didn't, and determined that the towers likely would have collapsed from the fires alone, without any aircraft impact damage or damage to fireproofing. You can read about those here.

Well, Jill, that should keep you busy for a while. :) But don't hesitate to ask if you're having trouble understanding something.

Best regards,
Mark