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Politics : Bush-The Mastermind behind 9/11? -- Ignore unavailable to you. Want to Upgrade?

To: sea_urchin who wrote (10023)	2/17/2005 12:20:12 PM
From: LPS5	Read Replies (3) \| Respond to of 20039

Is Dr. Thomas Eagar, professor of Materials Engineering and Engineering Systems at the Massachusetts Institute of Technology, a "government disinformation agent"? :-) ***** NOVA: The Twin Towers collapsed essentially straight down. Was there any chance they could have tipped over? Eagar: It's really not possible in this case. In our normal experience, we deal with small things, say, a glass of water, that might tip over, and we don't realize how far something has to tip proportional to its base. The base of the World Trade Center was 208 feet on a side, and that means it would have had to have tipped at least 100 feet to one side in order to move its center of gravity from the center of the building out beyond its base. That would have been a tremendous amount of bending. In a building that is mostly air, as the World Trade Center was, there would have been buckling columns, and it would have come straight down before it ever tipped over. Have you ever seen the demolition of buildings? They blow them up, and they implode. Well, I once asked demolition experts, "How do you get it to implode and not fall outward?" They said, "Oh, it's really how you time and place the explosives." I always accepted that answer, until the World Trade Center, when I thought about it myself. And that's not the correct answer. The correct answer is, there's no other way for them to go but down. They're too big. With anything that massive -- each of the World Trade Center towers weighed half a million tons -- there's nothing that can exert a big enough force to push it sideways. Even traveling at hundreds of miles an hour, the planes that struck the World Trade Center did not have enough force to knock the towers over. NOVA: I think some people were surprised when they saw this massive 110-story building collapse into a rubble pile only a few stories tall. Eagar: Well, like most buildings, the World Trade Center was mostly air. It looked like a huge building if you walked inside, but it was just like this room we're in. The walls are a very small fraction of the total room. The World Trade Center collapse proved that with a 110-story building, if 95 percent of it's air, as was the case here, you're only going to have about five stories of rubble at the bottom after it falls. NOVA: You've said that the fire is the most misunderstood part of the World Trade Center collapse. Why? Eagar: The problem is that most people, even some engineers, talk about temperature and heat as if they're identical. In fact, scientifically, they're only related to each other. Temperature tells me the intensity of the heat -- is it 100 degrees, 200 degrees, 300 degrees? The heat tells me how big the thing is that gets hot. I mean, I could boil a cup of water to make a cup of tea, or I could boil ten gallons of water to cook a bunch of lobsters. So it takes a lot more energy to cook the lobsters -- heat is related to energy. That's the difference: We call the intensity of heat the temperature, and the amount of heat the energy. pbs.org ***** e