Hm, I just thought you smelled like a US shill as I don't know you nationality or anything else about you. If you present your self with full style we can discuss.

I still cant discuss if you are only intending on make statements with out considering what I say as well.

I am an architect, I know a lot about actual building structures. I presume you know ship safety and structures better than I do, as that is what you do/did. I do buildings, some very big ones. I work with and direct engineers on large structures all the time.

Are you able to able to have a fair discussion with me?

Of course. Just present your self! Do you know any building that can collapse from top ... by gravity? What architect would build it?

No one designs a building to collapse. Are you retarded?

No, but the **Challenge** is to build a structure A that collapses by itself, when its top C drops on on the bottom part. C = A/10.

US authorities say it is possible and that terrorists used the system to attack USA 911 2001.

I suggest it is not possible and that the terrorists used explosives to destroy the WTC at NY.

Do you understand the difference?

Yes, I know the difference. They didn't use explosives, unless you consider a fully fueled Boeing 747 an explosive.

Again no one designs a building to collapse. It's not a design feature.

Getting a building to collapse where Section C falls onto Section A and causes Section A to collapse is nothing but simple physics and math.

Consider Section A and Section C two separate objects. The top floor of Section A is now the roof of the building. The roof of any building can only hold up so much. And even less when the object is impacting the roof with momentum. Each tower of the WTC had a mass of approximately 500,000 tons (just building material). The planes struck the towers at the 77th and 93rd floors. That's 33 floors of mass and 17 floors of mass above the new "roof". Using simple math, 500,000 tons divided by 110 floors (obviously some floors will weigh more than others plus there were multiple basements) is 4500 tons per floor. Rounding down that 4000 tons per floor for simplicity. Again simple math, 17 multiplied into 4000 tons is 68000 tons for the one tower and 33 multipled into 4000 tons is 132,000 tons. Now tell me which "roof" of any building that is going absorb the impact of an object that has a mass of roughly 68,000 tons and with the other tower 132,000 tons.

Even if you eliminated the mass of 6-8 floors from each where the airplane struck, thats' still ~44,000 tons and ~100,000 tons that fall and impact from a height of 6 and 8 floors above.

Estimated energy at the moment of impact would be ~8 Billion joules (40k tons @ 6 floors) and ~26 Billon joules (100k tons @ 8 floors). (Couldn't find the floor height of WTCs but I assumed ~12ft per floor)