The 90,000 ton estimate came out of a discussion I had with Jim Hoffman of 911-research. Here was my analysis which was posted at http://www.911-strike.com/demolition_explosive.htm :

Hoffman’s first draft of his paper relied on my estimates of the volume of concrete in the towers. In my “powder analysis” I estimated that the mass of concrete in the towers was 650,000 tons. This was based on reports of the total amount of concrete poured for the WTC, which probably included plazas, roads, subways and so forth, in addition to the towers themselves. This was probably a serious over-estimate (although it would have no effect on the conclusion of the “powder analysis” since the gravitational energy per kg of concrete would be essentially unchanged.)

From the FEMA report, for the floors of each WTC tower, we have ~40,000 sq ft of floor area (including the core) * 117 floors * 4″ thick of “lightweight” concrete (5″ in the core), which works out to about 58,000 cubic yards.

“Normal” concrete ways about 2 tons per cubic yard, but “light weight” concrete can be anywhere from about 600 to 3000 pounds per cubic yard. If we take a figure towards the high end of the range, we would estimate about 90,000 tons of concrete, but the correct figure could be much lower.

Additionally, all of the exterior columns (and presumably core columns and spandrel plates as well) were coated with several inches of a fireproofing plaster containing either asbestos or “inorganic fibers” which presumably might include fiberglass. From the Guardian, the exterior columns were about 13″ square (240 columns) and the core columns were about 14″x36″ (48 columns) so the surface area of all the columns would be 17280 square feet per floor, or 2 million square feet for the entire building. Covering with a 3″ layer of fireproof plaster would require 19,000 cubic yards, which could easily amount to another 10,000 or 20,000 tons of fiberglass-rich material.

Overall, the mass of concrete and fibrous material in each WTC tower is probably not more than 110,000 tons. This revised estimate was used in Hoffman’s later revisions of his paper.

As you can see, this was nothing more than a very rough estimate. So if there’s some calculation where it’s important to know an exact number, I can’t claim to have that information.

Also, I noticed that my very early article “Proof of controlled demolition at the WTC” was linked in the thread at sciforums. I agree with the posters who said that this article contained some serious errors. My retraction is posted at http://www.911-strike.com/demolition.htm .

I then turned to your home page and am happy to learn that you are “from Eugene Oregon”, where I reside, persisting in my life-long penchant for political confusion and ignorance.

Regards,

Les Jordan

Gerard contacted me a while ago and asked me to pull down all of his materials from my sites. I thought I’d complied with that request.

So I’m confused because I don’t understand what article you’re writing about.

I see the point of researching things as finding something that fits the facts, and until I find that I will keep doing research.

Dianne

It isn’t that groups of 150 or less will directly take on larger organizations, but rather that they (and combining the other lessons Gladwell discusses) become much more effective and cohesive environments to spawn and spread new memes and such from out into the larger society, and possibly under the radar. That is, especially if they can be populated with enough individuals described as Connectors, Mavens, and Salesmen, the modern equivalent of fishers of men (not in the Atwill context though).

In fact, Gladwell mentions that there is a school of thought that hunter gatherers would not have exceeded permanent groups over that amount for the exact same subconscious psychological motivating factors.

Without taking the time to elaborate on those underlying “channel capacity” factors, this points to the subsequant sociological need for the instantiating of social hierarchies within all post-hunter gatherer societies, including Communists, that maintain operative groupings of individuals larger than this amount.

Thus, the 150 concept sounds like an interesting potential core concept around which to evolve to a Georgian socio-economic system, and with which to keep in mind as an amplifying “Tipping Point” tool for advancing desired social changes. After all, even militaries have always kept their operational “companies” close to this number, because they found that this is what maintains the most cohesive group order, for the exact same reasons as all other groups.