Nyctohylophobia

An old Wikipedia entry summed up the Twin Tower collapses thusly (I bolded the part about the collapse symmetry/straight down vs. topple issue): "Most engineers view the collapses as sensible and even predictable given the conditions. According to the view of these engineers, the jet fuel acted to instantaneously spread the fire. The impact furtheremore [sic] blew insulation off of steel beams. Because of these factors, the steel was quickly heated enough to lose significant strength. Together with the structural damage, the softening of steel caused failure. Once failure occurred, the monolithic mass and internal center of gravity allowed each tower to fall in only one direction: straight down. This view has been officially confirmed by forensic analysis of key components of debris." You can view a cached copy of the original article, which has since been drastically changed, here.