The official theory of Building 7’s collapse is shown to be implausible by the inability of the official theory’s authors to generate a computer model of the collapse that even remotely resembles the observed collapse.
The National Institute of Standards and Technology issued its final report on Building 7 in November 2008, more than six years after starting its investigation. Because almost all of the physical evidence had been destroyed, NIST’s theory depended largely on its ability to reproduce the collapse through modeling. Despite being able to adjust inputs in order to achieve the desired result, NIST’s model does not come close to reproducing the observed collapse, as shown in the picture below:1
The discrepancy between NIST’s model and the observed collapse is also apparent by watching the two video animations of NIST’s collapse model and comparing them to video footage of the observed collapse.
The clearest discrepancy is the deformation of the external structure in the model, which does not occur in the observed collapse. The second obvious failure of the model is that it never shows the period of 2.25 seconds of free-fall that NIST finally acknowledged in its final report.
Had NIST attempted to model a controlled demolition of Building 7, it undoubtedly would have been very easy to replicate the observed collapse. NIST’s inability to come close to replicating Building 7’s collapse through modeling demonstrates the implausibility of NIST’s theory.
A detailed, technical critique of NIST’s theory by structural engineer Ronald H. Brookman can be found at the Journal of 9/11 Studies.
 NIST NCSTAR 1-9A, “Global Structural Analysis of the Response of World Trade Center Building 7 to Fires and Debris Impact Damage,” Washington, DC. November 2008. p.111. http://wtc.nist.gov/NCSTAR1/NCSTAR1-9index.htm