Long-lived civilizations must be rare because if they were not, we would be living in one
The Human Cannonball doesn’t usually remember much about each flight, aside from a quick impression of soaring through the air. […] She has just been shot out of a 24-foot-long air-compression cannon and travels between 75 and 100 feet at a force of 7 g. That’s greater force than a roller coaster, greater than a Formula One racecar, greater than the space shuttle. A force powerful enough to have caused some human cannonballs to pass out midflight. […] She’s in the air approximately three seconds.
