9/11 Debate

[Mav]

There are a few things that bother me about the whole thing.

1. Buildings were designed to withstand a plane crashing into them.
2. Fire has NEVER bought down a skyscraper.
3. Buildings fell down extremely quickly, both in terms of time after they were hit....and once it started.

The claim the buildings were designed to withstand a plane crashing into them is a very weak link in your circumstantial case. The inference is that the design was so foolproof that the building couldn't possibly be taken down by a plane. To that I say: the Titanic. When it was launched, the unequivocal claim was made that it was unsinkable. It was designed that way. One of the biggest threats at the time to shipping was icebergs. By implication, the Titanic was designed to withstand a collision with an iceberg. I'm building up the dramatic tension here before the big reveal ...

Interestingly enough, there's another similarity with the collapse of the WTC buildings. One theory is that there had been a fire in one of the Titanic's coal bunkers which continued to smoulder but the owners decided it should set sail anyway on its maiden voyage. The argument goes that this fire may have weakened the metal in the hull, leaving it vulnerable to an iceberg collision. And here we are a century later talking about fires in the WTC buildings weakening the integrity of the metal supports. Spooky, hey?

Another eerie parallel is how quickly the unsinkable Titanic sank, although you'd have to say that the WTC buildings hardly collapsed quickly (unfortunately for the firefighters who went into them).

Marketing hype tends to add "-proof" to products. For instance, bullet-proof glass isn't a real thing. It resists bullets but it isn't completely impenetrable. I guess "bullet-resistant glass" isn't quite as reassuring.

And just why are we saying that the design of the WTC buildings was capable of resisting plane collisions? They opened in 1974 and I think we'd all agree that engineering has come a long way since then. Even with upgrades made from time to time, we're talking about 30 year old buildings when they were destroyed. As others have noted, planes sure became a lot bigger after they were designed. And just how were they tested? Was there some scale model they used. Or did they use 1960s computers to do a worst-case scenario?

An interesting engineering problem occurred with a building of the same vintage: the John Hancock Building. Professors teaching differential equations celebrate this building as it featured an amazing flaw. It just happens that there's a thing called vortex shedding which means that considerable wind forces are applied to tall buildings that are built just so. These forces are sinusoidal, so they move the building back and forth. In this particular building, those forces led to windows popping out and it became known for plywood filling the holes. They had to introduce a tuned mass damper which was a large weight on a near-frictionless surface in one of the upper floors attached to the building by a system of springs. This created a system governed by a 4th order inhomogeneous differential equation which could be adjusted so that the building remained static while the weight, the tuned mass damper, oscillated within it. What a snafu!

The Green Building at MIT, opened in 1964 had similar problems which was a bit embarrassing given it was designed by MIT graduates. Apart from windows popping out and the like, the high winds the building faced prevented anyone from entering or leaving the building by its foyer and they had to use tunnels to escape. 

Fact is, it's pretty hard to design anything that's totally impervious to every eventuality. And real life has a way of throwing up unanticipated challenges. One great example is the sinking of the Bismark. Again, that was a ship that was virtually unsinkable. Its armour-plating was thick as. Indeed, when the British battleships engaged it, it was hardly damaged while HMS Hood blew up when one of the Bismark's shells happened to hit the magazine holding its ammunition. It sank within 3 minutes despite the British public being told it was unsinkable. Even when struck by torpedos dropped by British planes, there was hardly a scratch on the Bismark. Until one torpedo struck the rudder of the Bismark and failed to explode. If it had exploded, the Bismark could have made it to port. But the steering was jammed and the Bismark was condemned to sailing in circles. That enabled forces to muster and bring it down.

Who the hell would ever have thought that would happen? You'd have more chance of winning Tattslotto. But that's the thing. All the best plans of mice and men are oft ripped asunder. And saying that something never happened before doesn't mean it won't ever happen. There's a first time for everything.