What causes knuckles to crack? Scientists now think they knowThe sound of popping knuckles has long been a source of bafflement for scientists. The verdict: the cracking sound was down to the rapid separation of the joint and bubble formation, not bubble collapse. “Their main finding, that theoretical bubble collapse can create sound, is not surprising,” he said. “Some people cannot crack their knuckles because the spacing between their knuckles is too large for this to happen,” said Barakat.

Source: The Guardian March 29, 2018 13:00 UTC