They shall be known as Bush's Laws of Motion

[OnTheOtherHand]

26. this is where the word "cartoon" is hard to resist

To put AZCat's point about local failure more vividly, you might as well argue that a brick can't smash through a car windshield because, after all, the car has so much more mass than the brick.

Let me attempt to anticipate a likely defense mechanism: yes, yes, of course that is not a good model of the tower collapses. It isn't intended to model the tower collapses; it's intended to illustrate the gaping hole in your reasoning. That "more massive object" isn't just an object; the "lower block" isn't just a block. Your model neglects a really basic fact about a building: it's, y'know, built. It isn't a point mass; it has components and structure.

Of course, the "upper block" isn't just a block, either. Damage is occurring to both the upper floors and the lower floors; ever more mass is falling, some of it within the footprint of the tower, some of it outside. The upper floors don't have to remain intact all the way to the ground (or the pile), nor do they have to smash everything in their path.

If you can't even wrap your head around this possibility -- if you can only imagine that the upper floors drop onto the top of the lower floors and rest there, because there are more lower floors than there are upper floors -- then I guess you'll be pretty puzzled by the professional literature.