Sadly, last night, the impressive spire of the cathedral of Notre Dame de Paris fell onto the roof of the cathedral. Constructed of wood and covered with lead it burned for some seven hours before the weakest point gave way and the spire came down. I expect many others have drawn mental comparisons between the collapse of this spire and the structure called the “spire” which was demolished along with WTC1 in New York on 11 September 2001.
The collapse of the 19th century spire can be seen on several videos showing what would be expected to happen in accordance with Newtonian physics, the laws of motion and gravity. Newton’s first law (Law of inertia) is obeyed in that an object when acted upon by a force will continue in a linear direction unless acted upon by another force. In this case the force acting upon the spire was gravity (a natural force) which came into play when the point of least resistance gave way allowing the spire to fall. Importantly the spire continued to fall in the same direction until it was acted upon by another force – the cathedral roof – which stopped its further linear momentum.
This second picture shows that the spire continued in the same outward direction in which it started (featured image).
While this article compares spires it is fair also to say that the whole of the North Tower fell without apparently following the laws of Newtonian physics though a case could be made for the stronger nuclear forces which can compromise atomic structures.
The “spire” which was a core column of WTC1 (North Tower) has been the subject of much speculation. It falls several seconds after other parts of the building have already fallen. It then appears to vanish into its own footprint, that is, straight down through the path of greatest resistance. Whereas the spire on Notre Dame cathedral leaves behind the structure that had been previously supporting it – the equal and opposite forces of Newton’s third law. Watch how it falls in the video below and imagine the stronger support structures beneath it. Where did they go?
As with the spire of the cathedral, which was a much weaker structure, one corner of WTC1, where the initial fire took place was weaker than other parts and the top section started falling, like Notre Dame spire, outwards. Unlike the spire in Paris it did not continue on that path. This photograph shows the original momentum and if a straight line was to be drawn from the corner edge the degree of tilt can be seen.
That still was taken from the video linked here. To obey Newton’s laws it would have continued in the same path for the simple reason that it is the path of least resistance. There are currently more than 3000 qualified engineers and architects who are seeking to find out what really happened almost 18 years ago. Below some of the pioneers of this movement explain why Newton’s laws of motion were not followed when the twin towers and Building 7 collapsed in almost freefall.
I hope people can see from the way the spire of Notre Dame fell that the twin towers -which were also much stronger below compared to the compromised section at the top – should have followed a similar path.
John – As an engineer with 25 years professional experience I can tell you that there is no inconsistency between the laws of motion and the collapse of WTC1. Keep in mind that all three laws act in concert, and that real life events are far more complex than the rudimentary principles taught in school and university; which are deliberately simplified to aid understanding. You may also be missing the influence of inertia and rotational dynamics in your analysis.
Mark, thank you for your comment. As an engineer too (toolmaker) I agree that the laws act in concert and it is a complicated issue. That is one reason why any proof can only come from modelling. Here Jonathan Cole models (several physical models) of how the twin towers could have fallen but cannot get them to fall without deceleration. I would value your comment on this. Better still if you could direct me to a physical model which behaves in the same way as the twin towers fell.
Oh John – those models and the conclusion are cr@p!
I was on board and open minded until I saw the models with their complete failure to replicate the structural vertical membranes with any similarity. None of the models show any attempt to simulate accurately the relative strength and stiffness of these elements.
As a general rule of thumb, if a model fails to replicate real events, and the model comprises simplifications or substitutions, the conclusion to be drawn is that the model is flawed. To do otherwise is intellectual honesty and likely the result of cognitive bias.
You need to model it yourself Mark. I suspect you would find something wrong with my models too.