Someone bent my ear again on 911 conspiracy theories, and I've had jigsaw-puzzle-solving fun digging through the details.  Also, I feel we should consider evidence for even pretty crazy-sounding claims when the evidence offered meets high enough standards.  To his credit physicist Steven Jones has published papers meeting such standards:

• J. of 911 Studies:  Tiny iron-rich spheres were common in 911 dust, showing very hot fires.

• The Environmentalist:  Surprisingly energetic stuff kept rubble burning long and hot.

• Open Chemical Physics J.:  Advanced nano-thermites were common in 911 dust. 

I conclude the twin towers probably held big chucks of hitech pyrotechnic materials quite uncommon in office buildings.  And a few hundred pounds of this stuff spread around the pillars of a single floor might well bring down a tower. 

BUT, I am unpersuaded by claims that plane crashes could not have induced the towers falling as they did, the sounds heard, the warnings voiced, etc. (E.g., hear him and him.)  Aside from the above findings, the match between simple theory and observation seems about as close as we should expect, given this complex and unusual situation; it would be crazy not to expect a few anomalies between simple predictions and what we saw.

 So I see two main scenarios to consider:

1. Huge buildings known to include CIA offices happened to hold big chunks of hitech pyrotech when the planes hit.

2. Someone conspired to make planes, by themselves able to topple towers, hit the floors where very-well-protected pyrotech was hidden, and then triggered that stuff just when buildings might have fallen anyway.

Without some further concrete evidence, scenario #1 seems to me overwhelmingly more likely.

This post made me reflect again on why moderate uncertainty here feels like "uncanny valley."  If I told everyone there was a 10% chance of something they thought pretty crazy, nine times out of ten, it would confirm that I'm crazy.  One time out of ten I'd be vindicated, but even then folks might say I was crazy but lucky. 

Or hindsight bias might make them think it should have seemed pretty likely.  I'm acutely aware that the few of us who predicted the web when others called it crazy get little credit today; in hindsight the web seems inevitable.