00:00Someone just cracked their knuckles next to you.
00:01Here's what actually happened inside their hand.
00:04Pushing the joint pulls the bones apart,
00:07making protective gas bubbles pop.
00:12Meet the joint capsule,
00:14a tiny sealed pocket of fluid
00:16that cushions every knuckle.
00:21When you stretch the joint,
00:23the pocket suddenly has more room
00:26than the fluid can fill.
00:31So gas dissolved in that fluid
00:33rushes out and forms a bubble
00:36instantly.
00:39That bubble collapses just as fast
00:42and the pop you hear
00:43is the sound of it bursting.
00:51It's not your bones grinding
00:53and it's not your joints breaking.
00:55It's a tiny gas ball living for a split second.
00:59The popping doesn't cause arthritis.
01:02Science has checked.
01:03Your joint just needs about 20 minutes to reset
01:06before it can pop again.
01:09Hmm.
01:10Hmm.
01:10Hmm.
