In the thread before the last one, I had asked Pants-of-dog what laws of physics support the official collapse hypothesis, the Bazant/NIST "crush-down, crush-up" theory. After much delay, and not until the next thread, Pants finally mumbled something about
Conservation of mass and conservation of momentum are the two main ones.
When asked to explain how these laws are used in the NIST/Bazant hypothesis, he could only provide a vague explanation:
Conservation of mass tells us that the upper block does not magically disappear into thin air. So, once it started falling, all the mass had to go somewhere. Using the law of gravity, we know it went down. Using the law of conservation of momentum, we know that as it went down, it imparted energy to the lower floors.
The NIST/Bazant hypothesis describes an alleged upper block of storeys (not verified by the video evidence) that "crushes down" through the larger, intact building (with the layer of rubble in betwen helping it) then gets "crushed up" at the end by the very pile of rubble that had been helping it crush the rest of the building, all in the space of 13 seconds. This drawing by Anders Bjorkman helps us to visualize this:
If you doubt the accuracy of this drawing, you can view Bazant's own picture in Fig. 2 on page 22/29 of his last revision, found here.
The Twin Towers were constructed with 240 perimeter structural steel box columns and 47 larger core box columns, ranging from 36"x16" to 52"x22", forming a dense core structure which, alone, comprised 25% of the total area in the buildings' horizontal span.
The NIST supporters have not successfully addressed four gaping flaws in their theory:
1) a step-by-step explanation of events after the collapse initiation
2) evidence of the existence of the upper blocks through the collapse progression
3) an example of top-driven gravitational collapse (although they've tried!) and/or the law of physics that would explain it, and
4) math that accounts for what actually occurred, rather than what is hypothesized, and that is supported by accepted physical principles.
Pants-of-dog has now begun the discussion about the laws of physics that supposedly explain the crush-down, crush-up hypothesis: the laws of conservation of mass and conservation of momentum. We await a more specific explanation of this.
Pants-of-dog has asked us/me to explain how the NIST/Bazant crush-down, crush-up theory violates Newton's First and Third laws.