Take a close look at the manner in which WTC 7 collapses straight down. For the building to collapse in this fashion, all of the load bearing supports would have had to fail at exactly the same time.
The claim that the collapse was the result of a fire requires the fire be equally distributed throughout the entire floor of the building, providing equal heat for an equal amount of time, so that all the load bearings members would fail at the exact same moment.
Do you find this plausible?
9/11/2001 ABC News broadcast:
John Miller: "If there can be any good news about a day like today the collapse of 7 World Trade Center, the building they were so worried about injuring rescue workers, has freed up rescue workers to go into the area and they are now moving in in groups of 20 and 50 as their teams are designated..."
Peter Jennings: "So the principal danger to the rescue teams has been eliminated..."
“Amazing, incredible, pick your word. For the third time today, it’s reminiscent of those pictures we’ve all seen too much on television before, where a building was deliberately destroyed by well placed dynamite to knock it down.”
CBS News anchor Dan Rather commenting on the collapse of Building 7 - September 11, 2001 at approx 5:30pm EST.
When buildings such as WTC 7 are demolished the collapse is initiated by an explosion in the central area of the basement. This causes the building to collapse in on itself and minimizes damage to surrounding structures [full details].
The video enlargement on the right shows part of WTC 7's roof crumbling seconds before the collapse. The only logical reason for this occurrence is the building was rocked by a powerful explosion.
The following video (screenshot left) compares the collapse of WTC 7 to a controlled demolition. The characteristics and speed of the collapses are all but identical. Diesel fires do not collapse a building in this manner.
Here is the audio spectrogram for the above, indicating the start of the explosion.
9/11/2001 radio broadcast: "...I was just standing there, ya know... we were watching the building [WTC 7] actually 'cuz it was on fire... the bottom floors of the building were on fire and... we heard this sound that sounded like a clap of thunder... turned around - we were shocked to see that the building was... well it looked like there was a shockwave ripping through the building and the windows all busted out... it was horrifying... about a second later the bottom floor caved out and the building followed after that... we saw the building crash down all the way to the ground... we were in shock." [197kB wma download]
Note the highlighted smoke coming from the upper floors (Click images for full size)
Note the obvious rectangular area of windows blown out just as the collapse starts. While many blown windows are explained by the bellowing of air escaping outwards as ceiling crash down onto floors, this clearly synchronized event suggests explosives being used to cut not only the load bearing members but to sever the lateral supports as well, causing the endfs of the buildings to collapse in towards the center, minimizing damage to adjacent buildings. Again, this is a sign of a controlled demolition.