various slow motioned footage of the world trade center towers coming undone. the official "collapse" times are based on recorded seismic activity on 911. according to NIST the collapse times are as follows: "Enormous advancing dust clouds obscured the collapses, making it impossible to calculate the collapse times through visual evidence, but analysis of seismic data from the nearby Lamont-Doherty Earth Observatory at Columbia University shows that the north tower collapsed in 12.73 seconds, and that the duration of the south tower collapse was 10.53 seconds...[20]" [20] is from: "Thus it transpires that the seismic records imply the crush-down phase to have lasted 12.59 ± 0.5 s for the North Tower, and 10.09 ± 0.5 s for the South Tower." "These durations match reasonably well the durations of the crush-down phase calculated from Eq. (2), which are 12.73 s and 10.53 s for the North and South towers..."