I think that you are a bit too close to the problem over the issue of explaining technical details to non technical people.

That's probably true. I used to like doing it, not so much any more, yet I unconsciously jump on it out of habit, then end up wishing I hadn't because it's all for naught. Can't hold anyone else responsible for that.

That is tackled daily by the smart use of visual aids and analagies to reach a target audience where support is required for a tech project.

Yes, by people who are getting paid to do a job. There is a difference. Occasionally I have to get co-workers to understand what I'm saying (without pissing them off) and I haven't failed on that count - in decades.

You say that you have *tried* to make it simple. But you have still failed to explain why you think that more concrete was crushed than existed.

The percentage of crushed material in Kuttler's model as a fraction of total mass exceeds the fraction of concrete mass in the real towers. That is a fact, and that's what I latched onto. I failed to notice that Kuttler's model was nearly all concrete. In this respect (as well as some others), his model differs markedly from others who've attempted the same thing. I did fail to notice that. However, that doesn't redeem his effort; in some ways, it's worse. The very nature of the model which I overlooked makes it a gross violation of the laws of physics, as Mick describes above. And, because of his overestimate of the amount of concrete,

*he still is guilty of crushing more concrete than there was in a tower,* though it's not by the extreme margin I indicated.

Let me try an analogy. It's going to be ridiculous to get the point across, don't get too caught up in that aspect. Suppose two trains are headed towards each other at high speed on the same track and collide. Naturally, they shred each other into rubble which is strewn all over the place. Someone like Kuttler comes along and, noticing that many of the wheels (which are solid steel) are bent and deformed, decides to model the collision. Since he's only interested in what happens to the wheels, he models the physical system of the two trains using only the wheels. To his surprise, the results do not match reality.

Do you see what's wrong with this model? There were more than wheels in the original system. The wheels constitute a mere fraction of the mass of the system and it makes a big difference in the expectation and result. A bunch of wheels in collision will not act like the same bunch of wheels integrated into trains which collide. Another way is to say there were 100 cars in each train and he chose to model it with only 10 cars. It's not going to be the same.

Another analogy is having two balls of clay attached to the front of each train and have the trains collide at 1mph. The clay balls are smashed flatter than pancakes. Kuttler comes along and doesn't believe two clays balls impacting at 1mph could ever be smashed flat. So he models only the clay balls moving together at 1mph and, sure enough, they don't compress each other down to thin sheets. Do you think leaving the train out of the formulation had anything to do with it?

Like I say, extreme and ridiculous examples to get the point across. It is sometimes possible to model components of a system in isolation, this is not one of those occasions. When you construct a model composed of components making up only 10% of the total mass, and of that fraction 4/5 of it is concrete, and you seek to crush most or all of it, it's not at all representative of the whole system. The omitted 90% of mass makes all the difference in having that even be possible.

Then, in modeling only the wheels of the train, he deliberately violates an immutable law of physics, namely momentum conservation. The results, therefore, are entirely divorce from reality.

Both myself and @

qed read the Kuttler paper and concluded that in one scenario he made an assumption that the entire building was made of concrete and then by crushing and ejecting 1% of that concrete at each floors impact then an estimate could be made of the time required for the total collapse to occur.

You then began to make a claim that the scenario above meant that he was crushing more concrete than existed. That was clearly wrong and I saw that instantly. As you later said in a post -- " It's not a matter of ejecting more mass than there is in total, that cannot happen because it's always a fraction less than one at each step." That was the obvious fact that I saw from the start - and now don't need to justify my earlier post to @

qed by an Excel spreadsheet. It was self justifying and I just stepped back for a second to consider.

First of all, because he overestimates the amount of concrete, he

*does* crush more concrete than

*existed in the building* when he crushes it all. That's still true. By most estimates, nearly twice as much. But he does not crush more than he himself had in the model. I missed the fact that his model consisted of "wheels only"; my bad, but the wheels-only part is just as mistaken or worse. He's not even modeling the towers. Why would you expect a valid result for the towers, even if momentum conservation was observed?

That takes me back to the main issue. If ( in that ridiculous scenario ) 100% of a building is comprised __entirely__ of concrete floors floating 13 feet apart and then that concrete is all assumed to have been crushed during a collapse in order to calculate the time it would take - then how can that possibly lead to you to conclude that more than the original total was crushed.

He calculated the mass of the concrete, which by his reckoning turns out to be 17.3% of the real tower mass, but is 80% of his total model mass. He then crushed 40% of the total mass. I noted that 40% > 17.3% and concluded he crushed more than existed in the tower. My reasoning was wrong because 40% < 80%, and I failed to notice that 80% of his model mass is concrete. At that value, given his overestimate, he did indeed crush nearly the entire mass of concrete in the towers, but he believes it's only about half.

I hate to say it because it seems like I'm trying to downplay the fact that I didn't notice 80% of his model mass was concrete (that's what happens when only reading one section), but such a notion is so far from being an acceptable model of the tower collapse that it never occurred to me that anyone would think to do something like that. Would you expect anyone to model a train collision with only the wheels? And then start talking about "lower bounds for this and that of the TRAIN wreck"?

If you still can't explain that to me because I am incapable of understanding quantum physics so be it. But both myself and @

qed seemed to still not understand your 'explanation'.

I believe qed understands it, and I know Mick does.

Of course I am just focussed on this single scenario here. Clearly, Kuttler introduced many varied alternative situations to examine and there is danger that assumptions made for one are mistakenly carried over to another where they will not be appropriate. On this single - all concrete - no steel - 1% ejection per floor, scenario, I still fail to see how your claim that he crushed more than exists is valid. And if you can't explain that then its fine. I will just move on.

I hope I've satisfactorily explained both my error and his.