NIST has admitted that on 9/11 WTC Building 7 fell for a period 2.25 seconds at free fall. This means 8 stories of the resisting structure had to be removed simultaneously floor by floor to enable free fall acceleration. According to NIST the resisting structure was removed by _gravity_. Any structural engineer should see a massive violation of the law of conservation of energy here. Clearly a gravity driven collapse is impossible. There must have been another energy source used to remove the 8 stories of resisting structure in the way. Why has no one spoken up about this?