I’m going to ignore all the personal stuff.
So you watch this video and you have no questions? You just swallow the whole thing, you don’t think maybe you ought to check some of the claims out? And you call that being scientific? Why do you trust Chandler so easily? Do you know him or something?
Is controlled demolition the only possible explanation for what was observed of building WTC7? No it isn’t. The NIST account of the collapse is accepted by the vast majority of industry professionals. You, as a non-professional, can of course choose to believe Chandler rather than them. I don’t see how you have the technical knowledge to make that choice - no more do I.
The more you study Chandler’s claims, the less they stack up. Across the board he has presented evidence selectively, taken quotes out of context, or just simply failed to offer any reasonable explanation. The more I read about this, the more I am convinced that the Truthers – ironic name – cannot be trusted.
When Chandler says the building was falling at freefall speeds, he is lying. He tells you he’s lying within the video itself if you listen carefully enough. More of that in a moment. If this video is still available, then he is also deceiving us by showing and referring to the pre-circulated
draft NIST report, not the final published version.
Controlled demolition is not the only explanation, which means there is no irreducible ‘fact’ at the core of his argument. I’m going to give some quotes from JREF, a forum like this one set up in 1996 to examine unlikely claims from a scientific point of view. It’s not a political forum. Members include a wide range of specialists across many fields. Their level of expertise is obvious when you read their posts. Robust views are exchanged, as you might expect. The thread I quote from is massive and goes on for many years – please read the rest of it, it’s very interesting. (It starts here:
http://forums.randi.org/showthread.php?t=128194).
Just to add a bit of spice to it David Chandler himself joined the forum under his own name in order to put his case (not very satisfactorily but there you go). Several blatant ‘Truther’ trolls also intervene at times.
And if you think they’re all liars too, why don’t you join their forum and explain to them why? See how you get on?
Freefall – Chandler’s view
The official account is contained in the NIST report (National Institute of Standards and Technology 2008). Chandler says that NIST makes ‘dishonest claims’ about the rate of acceleration of the fall. In fact NIST was neither wrong nor dishonest, but it doesn’t give enough detail about the variation in the rate. The draft report only gave an averaged rate of acceleration for the whole period of the fall. However, for the first 2.5 seconds it is much faster (close to but not at freefall). Chandler sent them this information at the draft stage. NIST agreed with this and incorporated it into the published version of the document. This added a no more than couple of pages to a 1000 page report, the rest of which Chandler does not dispute. In its final form, there is no significant disagreement between Chandler’s figures and NIST’s on this issue.
However, Chandler is rather less than scrupulous with his own analysis. In the video you post he describes how he calculates the acceleration of the fall, which he says is close to the rate of freefall. This is correct as far as it goes. Because of the poor video quality there is a margin for error of 1 second, as both he and NIST observe. But now Chandler plays some language games: ‘The most accurate way to characterize the result is to say, the acceleration of the building is indistinguishable from freefall.”
No, it is
not the most accurate description. He’s just changed the meaning very significantly to allow people like you to say ‘
there was absolutely ZERO resistance to the collapse.’
Later in the video he drops the qualifier altogether: “For a significant two and half seconds the building was in
literal freefall.” NO IT WASN’T. Both his result and NIST’s give figures somewhat less than freefall rates. His own analysis, because of the margin for error, tells him it’s actually impossible for him to know this one way or the other. In other words, the collapse did meet some resistance from the start, which increased significantly after 2.5 seconds.
He also fails to take account of the prior internal collapse, as discussed below.
Chandler compared with NIST
Essentially, there is surprisingly little difference between the NIST account of the building collapse and Chandler’s. Where they disagree is in the interpretation. As one of the JREF professionals comments:
‘What you have found is an
effect. NIST agrees with that effect. What you are now claiming instead is a
cause, but you have not demonstrated that your cause is the one and only explanation. Until you do so, our argument remains with you.’
Note also the last quote I give below, where they point out the differences (and fundamental limitations) of trying to apply abstract, classroom physics to real-world, messy engineering problems. There is a reason why physics teachers teach physics and not structural engineering.
As I say the thread is massive but I’ve picked out a few interesting quotes:
1.
What you see on the video is the outside of the building, but that’s only part of the story. The building was already collapsing inside, as confirmed by the seismic record and the prior collapse of the penthouse. The internal collapse began about 10 seconds before the external wall comes down:
“THIS is the core of my (& NIST's) argument, that there was very little of the structural support of the external walls still intact when their collapse began.
The fact that the vast majority of the internal structure of the building had long since (~ 10 seconds) failed is indisputable from the collapse of the penthouses. Sequencing video evidence of reporters on the street hearing the collapse begin with lateral motions of the roofline of the building, you can reliably push the start of the collapse of the internal structure back 18 seconds before the external walls began to fall.”
2.
The term ‘freefall’ is inaccurate. No part of the building fell at pure freefall –however, one part fell at near freefall for 2.4 secs:
“Chandler says that the exterior North Wall falls "at G". He hasn't said a whole bunch that I've seen about the internal collapse process.
Chandler is wrong.
NIST says ONLY that the external walls fall at accelerations that are less than G, but rise for short periods to values that are "approximately equal to G". NIST says that the building as a whole does NOT collapse "from top down", but rather "from inside (column 79 - 81) spreading towards the external walls".
NIST is right. Mostly. They have made a couple of small errors.
NOBODY but you says "
the intact top part of WTC7 free falls". This silliness is, no doubt, a bad habit left over from your WTC towers nonsense….….My best estimates of the numbers are:
1. the average acceleration between 1.75 seconds & 4.00 seconds is .94G.
2. the peak acceleration between those two times is .99 G.
3. the time after the start of the collapse of the exterior wall that it took to accelerate from zero G's to .98 G is about 2.6 seconds.”
3.
The building does not fall as a single unit, as it might appear to the unqualified observer looking at the video. The collapse starts in one place and progresses:
“The whole top structure does NOT fall as a unit. It fails first near the core columns (79 - 81), and the failure wave moves horizontally outward towards the walls. It takes almost 7 seconds for this wave to reach the outer walls. CLEARLY proving that upper floors of the structure did NOT fall as an intact unit…….The internal structure does NOT fall in free fall. The pieces & parts collide with elements below, and are thereby slowed far below "free fall" acceleration.”
4.
David Chandler is a high school physicist, not a practicing structural engineer. This is how one professional views him:
“You are frankly incompetent in the field of structural engineering, structural mechanics and failure mechanics of large buildings. The ULTIMATE analysis ain't physics. It's engineering. It's messy. Things in the real world don't fall in a vacuum, they don't have zero friction, they don't behave like rigid bodies or perfect gasses.
You have been dealing in physics-type absolutes. You slide casually & carelessly from "fell at almost G", to "fell, for all intents, at G", to "fell at G". You then opine that "for something to fall at G, there has to be zero resistance". The correct phraseology is "for it to have fallen at approximately G, there has to be approximately zero resistance."
And, as I have drummed into about 20 baby engineers that I've helped mold in my career, "unless you know the cold, hard numbers as well as the nerdy error bands, you don't know Jack." Without an error analysis, you do NOT know how "approximately close to G" you can claim. Without a solid background in structural dynamics, you do not know "how approximately close to zero" can be the resisting force generated by a structure in the process of buckling.
You thought that your results proved something that was impossible in a gravity driven collapse of a building. And, in the pristine physics terms that you've phrased it ("it fell at gravitational acceleration'), it might be impossible. But once you throw in the real world's messiness, then your "impossible event" turns into "not surprising at all".
“I would be willing to bet my and my wife's entire pensions up against yours that no short of 100,000 engineers WORLDWIDE have looked at this. If there was a problem, don't you think that the majority of them would be screaming for anyone and everyone to pay attention?? Engineers (IMHO) like to analize things. Right??”
“….9 years and counting and not a single paper in an accepted academic peer reviewed journal in a relevant field. Not one.”
To summarise:
There is surprisingly little difference between the two accounts of the collapse. However, Chandler attributes the cause to explosives despite the fact that far less remarkable causes are perfectly possible. Unlike the vast majority of all the experts, witnesses and participants, who together number hundreds if not thousands, Chandler is overtly political in motivation whereas they are not.
It is manifestly untrue for him, or you, to say that controlled demolition is the
only possible explanation for WTC 7. And once there is doubt about the core of his argument, the rest of his extraordinary explanations about how the explosives got there fall to pieces.
Therefore by Occam’s Razor –the official collateral damage explanation is the one we should follow unless significant new evidence emerges.