Refutation of Dave Thomas Critique of my North Tower Analysis

I have been reluctant to enter into mudwrestling events with debunkers and propagandists for what I see as blatant disinformation. I don't see these debates as productive. They are not about deepening the inquiry into events but rather fending off ever-morphing attacks by people who engage in deceptive argumentation. I have better uses for my time. I find that ignoring them works just as well and allows me to get on with my life.

However one hit piece by Dave Thomas has been the source of repeated questions in my in-box from people who sense something is wrong with his analysis but are not confident enough of their grasp of the physics to be sure. Rather than continuing to write individual explanations in email responses I have now posted a refutation of the attack on the "Articles and Links" page here:

I hope this helps.

--David Chandler

" In order to deliver an excess force...

the falling block would need to lose some of its momentum, in other words slow down. Since the roofline is experiencing uniform downward acceleration, the top block is not losing momentum at all, so it cannot deliver an excess force. The measurement of the actual motion proves that it is not crushing the underlying structure at all. It is falling into a void as the underlying structure is being pulverized by other forces."

Actually, is this not the premise of Tony's 'Missing Jolt' paper?

Sorry you felt the need to address Thomas's "tied bag of rice" experiment. :) At first its childish simplicity fooled me, and I thought surely he must be making some point I don't quite see yet? After some time I realized, no, he really just missed the point.

Dave Thomas's attempts at finding "scientific" answers to the phenomena he needs to explain to endorse that model of the Twin Towers' collapses border on the comical. If he's attempting to mislead people with pseudoscience, then it's offensive both in its intent and in his assumption that his audience is that stupid.

I are already shot down the

I are already shot down the bag of rice video in comments on youtube. the experiment neglects time. My alias is thodal2000 on youtube

Nearly all the "debunking" theorems omit time derivatives.

The experiment in the video is not valid

The impulse equation (in non-calculus terms) tells us that the force delivered during an impulse is inversely proportional to the impact time. If you make the impact time twice as long, the force will be half as great. (That's the reason for padded dashboards in cars.) If you drop a solid object on a solid surface the impulse time is very small so the force is very large. Pouring the rice spreads the impulse over a greater time resulting in a proportionately smaller force.

The flaw in this demonstration is Thomas is using a spring scale with a response time comparable to the impact time of poured rice, so a solid hit and poured rice behave the same. The scale can't resolve the small impulse time of a solid hit. The pan is absorbing the momentum slowly as the spring extends. In this experiment the maximum impact force for the rice is believable. The maximum impact force for a solid object is not. What would be needed is a measuring instrument with a much faster response time capable of resolving the short time interval of the impact of a solid object on a solid surface.

An honest experiment would vindicate the impulse equation. (I wonder if Dave Thomas uses this experiment when he is teaching the impulse equation to his students?)

I think this in line with what indio007 was saying.

a measuring instrument...

"What would be needed is a measuring instrument with a much faster response time capable of resolving the short time interval of the impact of a solid object on a solid surface."

Fortunately, such instruments do exist in sufficient quantity: I would bet that the top of Dave Thomas' foot could detect the difference between the rock and the bag of gravel, though I need to refine the 'expletive rating meter' to better quantify the results.

Jokes aside, your work and clarity of thought is greatly appreciated David. Thanks.

Perhaps I didn't understand it then

I thought Dave Thomas's experiment was invalidated solely on the basis that collecting loose elements or particles into a conglomerate like a sack of rice or a bag of sand turns the disparate particles into a whole that has different properties and will behave differently in terms of weight and momentum. A concept that we understand intuitively, i.e.., a large stone falling on your car will do more acute damage than pieces of it would.