The world, despite how far we’ve advanced, still offers many mysteries.
Surprisingly, one of those mysteries was, up until recently, “Why do knuckles crack?”
According to this Washington Post article, researchers figured out the answer by using an MRI machine.
MRI scanners use magnetic fields and radio waves to form an image of the body. Researched had subjects crack their knuckles inside of an MRI, and are pretty certain they know what the cracking sound a person’s joints make is caused by.
The noise is made by the joint fluid forming a bubble.
Apparently, scientists have been at war for decades over what causes the sound of a cracking knuckle — the forming of the bubble, or the collapse of the bubble. The MRI data suggests the former.