I want to draw your attention to the concept of an "Educated Idiot".
It sounds contradictory, but Educated Idiots do exist. Like the racist psychology professor Philippe Rushton or (up until recently) the Climate Change-Denier, physicist and professor, Richard Muller. People with the right kind of education to know better can still get things completely wrong (particularly economists) because they subscribe to a dogmatic point of view and can't (or won't) think beyond it.
I call it a lack of critical thinking, but whatever it is people can, and will, put psychological black holes over certain issues that even their good education can't help them escape from. It can apply to just about anything as well, from the important to the mundane, however the biggest of these psychological black holes hangs over the tragic events of September-11 itself. Even people who understand physics and champion the scientific method can get 9-11 wrong.
Here's a simple physics test for all of you Champions of Science out there. Ready?...
Question: If the top 12 storeys of a 110-storey skyscraper collapsed down on to the 98-storey structure below it (due to a plane hitting the building at the 99th floor), given that every action has an equal and opposite reaction, how many storeys of the 98-storey structure would be left standing?
Option A: None of it. It would collapse at near free-fall acceleration to the ground without any resistance.
Option B: Approx 86 storeys would remain, because the 98 storey building underneath would use an equal amount of energy in its resistance to the falling 12 storeys above it. (98 storeys minus 12 storeys = 86 storeys still standing).
If you answered A, then chances are you don't know physics, and that's okay. Most people who don't know physics answer A. If you know a little physics and still answered A, then you may be the unwitting owner of a psychological black hole. But if you actually do have a proper education in physics and still answered A, then I'm sorry to tell you this, but you are, by the very definition of the term, an Educated Idiot.
The correct answer was B.
(Don't worry if you got it wrong though. This question gets even more difficult to answer when you remove the scenario of a plane hitting the building and yet it still collapses to the ground in a perfectly symmetrical free fall. See WTC7)
The question though, as to exactly "how" and "why" the WTC buildings fell that day, is not a physics question, but a moral question.