Video of the bridge falling shows it took four seconds.
"That's twice as long as if it'd been in a vacuum," he said.
Another way to think about the Switzerland accident: A cable car is about the size of a small car, Kakalios said. The cable car would have been going about 60 miles per hour on impact, he calculates. People survive car crashes of that speed, especially if air bags slow down the impact.
"Let's say that the time to slow you down from a collision increases from one millisecond to three milliseconds," Kakalios said. "That's still really fast, but it's three times as long, so you hit with a three times smaller force -- a force that would have killed you, now won't."
That's likely what happened to the baby in the cable car: The crash killed the baby's parents, but the baby was cushioned by a rucksack -- and, likely, the parents' bodies. Adults generally have a better chance of surviving a fall because a larger body can withstand more force.
Kevin Hines, who attempted suicide by jumping off the Golden Gate Bridge in 2000, believes that the position he entered the water -- as if he were about to sit down -- helped him live.