Last weekend, a 1-year-old girl in Switzerland survived a 100-foot fall in a cable car. A man survived a 500-foot fall from a New York City skyscraper. When the 35W bridge collapsed in Minneapolis, 13 people died, but many more survived the more than 100-foot fall. Even 2 percent of those who jump off the Golden Gate Bridge live.
How is it possible?
Although there are too many variables for a simple answer, physics explains a lot of it. Jim Kakalios, a physics professor at the University of Minnesota and author of "The Physics of Superheroes," says there are two main factors that can make survival more likely: maximizing air resistance, and maximizing the time it takes to slow you down.
"A cable car has the aerodynamics of a brick," he pointed out. "You have a large amount of potential energy at the top when the cable breaks, and the kinetic energy when you land is where the damage comes from. But instead of (all the energy going into) speeding up, some of the energy goes into the work of moving the air out of the way of the car. It was similar when the 35W bridge collapsed; the bridge span had to do all this work to push the air and support structures away."
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.
"But even if there is an optimal way, and even if you are able to bring yourself into that position during a fall, adjusting an inch this way or that could upset the (landing) and create the trauma that would crush your body," said Charlie Euchner, a case writer at Yale University who researched jumps off the Golden Gate Bridge for a book.
Falling into water doesn't provide a softer landing than concrete when falling from such a great height. Terminal velocity for a human is about 120 miles per hour. A skydiver reaches that in about 1,000 feet.
Most victims of bridge jumps or falls die of broken necks, not drowning, Kakalios said.
"They're going so fast that the water doesn't have time to get out of the way and it resists you trying to get in," he said.
Plus, there's the issue of water temperature and reaching the surface of the water if you do survive the plunge.
Several factors aligned to allow Hines to survive: After his perfect landing, Hines believes a porpoise held him above the water until the Coast Guard zipped by and rescued him.
Hines, who says he decided he wanted to live the second his hands left the railing, is now married, happy and fit, Euchner said.
"It's a story with a happy ending," Euchner said. Still, the reasons for that happy ending are murky, as they are in most cases of survival.
"At the end of the day, the researchers still said, 'Who the hell knows?' He got lucky," Euchner said.