American Society of Civil Engineers (ASCE) study;
Federal Emergency Management Agency
Building Performance Assessment (FEMA BPA);
9/11 Commission and its
National Institute of Standards & Technology
(NIST) WTC 1 and 2 study and report
NIST WTC 7 study and report
All government sponsored studies
assumed the original hypothesis of impact and/or fire to be correct.
To this day, this hypothesis has not been proved.