How could there possibly be no impact? Did the upper block slide 200+ feet to the side before it started to fall?
You have not read Nist, Bazant, Seffen & Co? Before the upper block, rigid + uniform density, starts to fall vertically, all 280+ columns in the so called initiation zone fail ... and disappear. Then the upper block falls. It takes 0.8-0.9 seconds to drop one storey = the initiation zone. Not seen on any videos, of course.
And then there is an impact. The upper block impacts the lower structure. But the upper block is neither rigid nor of uniform density. It consists of 280+ columns on which many floors are hanging. It is mostly air! The total cross area of all columns is abt 5 m² so each column has an average area of 0.017 m². Actually just thin plates 15-90 mm thick. So the columns above must impact the columns below. If they are misalligned 15-90 mm they will miss completely! Little less - they will slide off. No impact. No global collapse.
The lowest floor of the upper block - it is 4000 m² big - may drop on the uppermost floor on the lower structure ... but that is no impact. Nothing will happen according to Nist. You need to stack 6-11 floors on the top floor of the lower structure before ... the top floor drops down one storey. Not seen either on any video. And no global collapse due to that.
And none of the above is seen on any videos. On the videos we see how the upper block disintegrates before anything happens to the lower structure. WTC2 is very clear - there is a big explosion at the initiation zone tipping the upper block 20° sideways.
Some people suggest it was just one wall that collapsed in WTC2 causing this tipping but ... a second later the whole upper block of WTC2 disappears.
According Bazant and Seffen, in order for a gravity driven collapse to take place, the upper block must be intact (and have uniform density) and aligned vertically with the structure below all the time! It is this upper block, or its released energy, that destroys the lower structure, storey by storey during the collapse. The upper block should actually, at the end of the collapse remain intact on top of the rubble, according Bazant and Seffen. They forget to say that in their articles, so I have asked them to explain what happens to the upper block after collapse.
No reply of course.
BTW - the unform density of the upper block is 0.18 (tons/m3) or less than baled wool! Read my article, and you will understand how 'scientists' and civil servant engineers (Nist) are fooling the adult public ... with help from the media. Luckily they cannot fool children ... my audience.