This is a new (March 2017) feature on this web site. We are frequently being asked to explain things on social media forums. Rather than spend our energy on one-off answers, this page will be a forum where we can provide a more complete collection of answers
Q. Can’t the collapses of the Twin Towers be accounted for by the fact they were hit by huge jet liners and subjected to intense fires fuelled by jet fuel?
A. (David Chandler) No.
- The impact severed or severely damaged only a few columns. The plane was reduced to mostly shrapnel after penetrating the exterior wall, leaving little ability to sever core columns.
- The jet fuel (kerosene) burned up in the first 5-10 minutes, mostly outside the building in the fireball. The buildings survived the initial impacts. The collapses occurred much later, triggered by other events.
- People were seen standing in the entrance hole after the impacts, so it couldn’t have been all that hot.
- Steel, even if heated to softening, regains full strength when cooled.
- Heating steel beams takes hours because the large thermal mass wicks away the heat; steel temperature does not rise to air temperature after brief heating.
- Most of the building was not heated, therefore full strength.
- Pancaking floors do not explain the collapse because there were 47 massive core columns that needed to fail.
- The first downward motion of the North Tower was the T.V. mast along with the level descending roofline, well above the impact point; this indicates that all of the core columns failed simultaneously This could not have resulted from the fires.
- The roofline accelerated downward the entire time it was visible, at about 2/3 of the acceleration of gravity. The implications of this are spelled out in my paper, The Destruction of the World Trade Center North Tower and Fundamental Physics; a version of the paper with notes for less technical readers is available here; my response to Dave Thomas’ attempt to refute the clear implications of this paper can be found here.
- You can see waves of explosive ejections running down the buildings as shown in many videos including here, here, and here.
- The phenomena described above can all be explained by demolition with explosives but not by fire and impact alone. Yet NIST (the government agency under the control of the Bush administration assigned to explain the collapses) did not seriously investigate the possibility of explosives and in fact did not investigate how the buildings could collapse beyond what it called “collapse initiation.”