Does this really look like a "collapse" to you?  The buildings simply disintegrated into fine dust from the top down.  We are talking the mid-air pulverization of thousands of tons of concrete (each floor slab several feet thick, approximately 110 stories/floors).  Do you see those massive dust clouds?  That's concrete dust!  All that shit that blew all over Manhattan and all the way to New Jersey, covering streets and cars several inches thick?  That's concrete dust!  Apparently, the amount of macroscopic concrete at the site that you could pick up and hold in your hand was negligible.  What would cause thousands of tons of concrete to just jump up into the air and pulverize itself into fine dust?

Also, notice that many of the photos of the buildings disintegrating exhibit a "banana being peeled" type of effect, like peeling a banana from the top down.  There are other photos that show the effect much better than these, but you can definitely see it here.  What would cause this?

Notice the "cauliflower" shape of the dust clouds in the last photo.  What would cause this?  Is there any other phenomenon that you are familiar with that would produce this effect?

Question:  If a tree converted itself into sawdust from the top down, would you say that the tree "collapsed?"  If not, then why are buildings which disintegrate into dust from the top down described as a "collapse?"  What part of "this is not a collapse" don't you understand?