In response to “alternative theory” groups, the National Institute of Standards in Technology (NIST) has released an online fact sheet as a follow-up to their initial October 2005 technical investigation report on the fires and collapse of the World Trade Center (WTC) towers.
The initial three-year effort is considered as the most extensive account of the September 11, 2001 attack on the WTC and its subsequent collapse. However, there have been claims from "alternative theory" groups that factors other than those described in the NIST report brought the towers down.
To respond to a number of questions raised by such groups, NIST has posted a fact sheet on the investigation Web site, located at http://wtc.nist.gov. The fact sheet explains how NIST found no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down by controlled demolition using explosives planted prior to 9/11, or that missiles were fired at or hit the towers.
Instead, the fact sheet describes how photographs and videos from several angles clearly showed that the collapse initiated at the fire and impact floors and that the collapse progressed from the initiating floors downward, until the dust clouds obscured the view.
