9 - 1 1 R e s e a r c h papers

The North Tower's Dust Cloud

Analysis of Energy Requirements for the Expansion of the Dust Cloud Following the Collapse of 1 World Trade Center

by Jim Hoffman
[Version 4]

On September 11th, both of the Twin Towers disintegrated into vast clouds of concrete and other materials, which blanketed Lower Manhattan. This paper compares estimates of the energy sinks apparent in the pattern of destruction of the buildings to the admitted source of the Towers' elevated mass. In this paper, I develop a model of dust cloud expansion that, given reasonable simplifying assumptions and quantitative estimates, indicates that the North Tower's expansion energy sink was many times larger than the gravitational energy source.


Vast amounts of energy were converted from one form to another during the collapse of each of the Twin Towers in Lower Manhattan on September 11th, 2001. I examine possible sources and sinks of this energy and ask if the admitted sources can account for the energy consumed by the various sinks. I consider the case of the North Tower's collapse and examine two energy sinks in detail: the pulverization of concrete and the expansion of the dust cloud up to 30 seconds, and devote the majority of this paper to evaluating the second sink.

To date there have been a number of government reports and academic papers purporting to explain the collapses of the Twin Towers. With the exception of a paper by Professor Steven Jones, these documents have unanimously endorsed the proposition that the plane crashes and subsequent fires, perhaps in combination with faulty construction, were responsible for the total collapses of the Towers. While some of these documents have disclosed force calculations to support their conclusions, none has attempted to analyze the energy flows in play during the collapses. Most appear to accept the underlying assumption that the gravitational potential energy of the Towers -- energy stored when the Towers were constructed and furnished -- was the only significant energy source or the vastly dominant one, while some suggest that the fires may have helped supplement the gravitational potential energy in driving the collapse energy sinks.

Thus, to believe the official story requires us to believe that the combination of the Towers' gravitational potential energy and thermal energy released by combustion during the collapses was at least as great as the sum of the energy sinks.

In this paper, I will first evaluate these two energy sources. Then I will enumerate possible energy sinks and determine which ones are amenable to quantification. Finally, I will develop a model to enable computing estimates of one of the sinks: dust cloud expansion.

This paper is currently under development, taking into consideration critiques by various reviewers.
The apparent disparity between energy sinks documented in the collapses of the Twin Towers and energy sources admitted by the official government account is an important area of research.
The examination of this issue in this and previous versions of this paper should not be construed as suggesting that there are not simple lines of analysis that strongly indicate or prove that controlled demolition induced the collapses of the Twin Towers. Arguments for controlled demolition can be divided into two catagories: