The world athletics record for two miles run inside a stadium was set last week in Central England. The Ethiopian record breaker ran both miles at close to four minutes per mile. The world record for two miles run outside is already under the threshold.
Apparently, some experts once thought that running faster than four minutes for one mile was impossible, and only fifteen years ago there was discussion whether people were approaching their limits in athletics in events as distinct as the hundred metre sprint and the marathon. In both of these events, the world record has plummeted in the last decade. There is a fair amount of pessimism and resignation to human limits, which is usually misplaced.
The pessimism sometimes is shown in economics too. I am often told that someone's country is growing slowly even if the economy is booming, and that it will never catch up with developed countries' income levels. As in sport, the attitude is misplaced. In capitalist economies, catch-up is actually very rapid.