Ok, to all the Physics junkies out there.....?

Question

In your professional opinion, do you believe that fire is what caused the collapse of the World Trade Center buildings? Especially WTC #7?
Just a question, please don't crucify me.

Answer 1

this is a common problem for people with basic knowledge of physics and engineering. There are many problems which give misleading results when they are simplified too much. It may very well be true that jet fuel could not melt steel, but there are way more variables at play here other than melting temperature and amount of fuel. Don't forget about the force of the impact of the planes themselves, which was basically a complete transfer of kinetic engery into thermal energy.

Answer 2

the fire was ENOUGH to cause the collapse.

some wild theories say that a bomb was planted to destroy the towers... In my opinion, something like that wasn't necessary: the fire would have made it collapse anyway.

now, what really happened will forever be a mystery: have the towers simply collapsed because of the fire melting one it its levels down, and the rest of the tower falling with it, or has some knukkle head planted a bomb to make the towers collapse 5 minutes before they would have anyway? Big mystery!!!

And it really is, since all proof of that bomb would have been lost in the explosion and rumble.


PS: well, my answer isn't sompletly accurate: the fire AND the pressure from the upper levels made the tower collapse. I mean, if the fire had taken place of the topmost level, the tower wouldn't have collapsed. Not even the top floor: even if the heat was there, there wouldn't have been enough pressure in the mainframe to make it melt. It's a combination of both elements.
That also explains why a fire wouldn't necessarily destroy a smaller tower: the pressure wouldn't be enough.

Answer 3

Yes. The buildings themselves were designed to withstand major shocks, as evidenced by the fact that they did not fall immediately. It was the jet fuel that did it. That's why the hijackers chose flights headed for the west coast...the ones that would have the most fuel.

EDIT: Conspiracy theories on this level are absolutely ridiculous. And, more to the point, they do not satisfy the Law of Large Numbers. Just imagine how many people would have to know something about this if it were something other than what we all saw. We really landed on the moon, the earth is really a globe, and planes really did slam into the twin towers.

EDIT 2: If it really matters, I'm a PhD student in Applied Mathematics. However, I don't think it matters at all. I doubt most people here are working on any sort of advanced degree, but judging by their answers they're a lot smarter than I am.

Answer 4

The conspiracy theorists use simplified models. Who knows what else combustible was in those offices, or on the plane? I've heard some concerns about the relative burning temperature of jet fuel vs. the melting point of steel, but is this for steel under a load--and what about thermal weakening and the effects of inhomogeneous expansion on joints, etc. The planes clearly took out supports between the uppermost and lower floors--were the buildings designed to accomodate fire stress AND the impulse of several floors collapsing from above?

Answer 5

Yikes, I was accidentally watching on television and saw both strikes live, and the hits crumbled those buildings with such terrifyingly, masterful perfection, that if it had been to an empty building, it could have been described as scientific perfection! Those buildings were horribly, terrifically, irresistibly, prime target perfection, vertical collapsed before contact was made. It looked like the work of the world's most extraordinary engineering team that exists. The enemy must have calculated exactly where to hit both buildings for a specific mode of destruction.

Answer 6

"In your professional opinion [...]", This of course assumes that those who answer this question are in professions which give their opinions have merit. Being a "Physics [junkie]" does not necessarily mean you know what you are talking about.
Not one person who has responded so far has listed any circumstances in which they might be qualified to judge such a situation.

I was neither there at ground zero on the day it happened, nor do I hold any advanced scientific degree, and my guess is that the majority of other responders do not as well....making this question / opinion poll highly unscientific.

EDIT:
It would now seem that someONE, randy_savage_, has listed their qualifications.

Answer 7

Controlled demolition with thermite as an accelerant.

Many tall buildings have burned for hours, if not days, without collapsing. Two 100+ story buildings were taken down in mere minutes.

Answer 8

If the fires were hot enough to damage enough of the steel supports, then it is not hard at all to believe that fire was the culprit. And once the supports midway up the tower fail, the weight of all the falling floors above would cause the remaining support below to fail.

Answer 9

The towers were made to fall straight down in a disastrous situation. The towers were made to withstand fire. So after the planes hit the buildings they were already going to collapse. So i blam the planes and Osama's ***** ***

Answer 10

Unfortunately, that's probably what did it. The infrastructure was made of aluminum rather than steel, which had plenty of strength, but could not bear up under the combustion temperatures of jet fuel.

Burning jet fuel can reach maximum temperatures of about 980C, aluminum melts at about 660C.