["Bulletproof Radio, a state of high performance."

You're listening to Bulletproof Radio with Dave Asprey.

Today's cool fact of the day is about your knuckles.

Scientists have disagreed for a century over why cracking your knuckles makes noise.

They mostly talk about bubbles.

They're saying there's some low pressure somewhere and it's been a lot argument.

But in 2015, a new paper showed that the bubbles don't fully implode.

Instead, they persist in your joints for 20 minutes after you crack them, which says it's

not the collapse of the bubble that makes the noise, but it's the forming of the bubble.

But it wasn't clear how a bubble's debut could make those sounds that are audible across

a room.

So, engineers from Stanford and French University, whose name I will badly mispronounce even

in their living Canada called E. Cole or something, set up to solve the mystery.

They found out that that weird sound your knuckles make may come from bubbles that collapse

only partially.

They actually did a mathematical simulation of a partial bubble collapse to explain the

dominant frequency and volume.

Why the heck do you need to know this?

Well, you probably shouldn't crack your knuckles, but we still don't even know if that's really

bad for you.

But this is the level of complexity that's going on in our biology.

If someone says that can't happen, therefore it didn't happen and something did happen in

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