Chas. Like Thanos disintegrating half the life of the universe. Sure?
Finger snapping takes place in the blink of an eye and now, thanks to a new high-speed video, we can see the physics of snapping . The footage reveals the extreme speed at which the famous gesture occurs and shows that friction plus the compressibility of the fingertips are key to proper snapping, according to the researchers in their study published in The Journal of the Royal. Society Interface.
How long does a click last?
Just about seven milliseconds, roughly 20 times faster than the blink of an eye , according to biophysicist Saad Bhamla of Georgia Tech in Atlanta, USA. After sliding off the thumb, the middle finger rotates at a speed of up to 7.8 degrees per millisecond, almost what the arm of a professional baseball pitcher can achieve, according to experts.
Is this study of any practical use? That’s how it is. In addition to satisfying the curiosity about how finger snapping works from a physics point of view, the findings may help develop more versatile prosthetics.
“For the past few years, I’ve been fascinated by how we can snap our fingers,” explains Bhamla. “It really is an extraordinary physics puzzle at hand that has not been closely investigated.”
To investigate the physics behind the gesture, the experts analyzed a series of finger snaps with a high-speed camera while covering the snapping hand with a variety of materials. They used a combination of dynamic force sensors, high-speed photography, and automated image processing to analyze various finger clicks, using different thimbles to explore the role friction plays.
They found that it was a three-stage process : starting with the thumb and middle finger pressed together, storing energy in the tendons. The friction between the fingers serves as a latch, initially preventing the energy from being released, until, with an audible snap, the middle finger slides past the thumb and hits the palm. However, unlike other biological spring-and-latch systems, the team suspected that skin friction would play a larger role in finger snapping. They were inspired by the Avengers: Infinity War movie to recreate the scene of the supervillain Thanos in which he uses the supernatural gauntlet that allows him to erase half of the life of the universe. According to the laboratory experiment, Thanos’ snap would have been a failure. Why? Because the gauntlet offers too much friction and therefore leads to a much slower clicking. The bare fingers are the ones that provide an ideal level of friction for snapping.
Can animals snap their fingers?
There are other species of animals in which ultra-fast movements equivalent to the snapping of human fingers can be observed. These include, for example: termites, biting ants, grasshoppers, carnivorous ants, or mantis shrimp.
They all rely on a spring and latch mechanism for their quick movements, allowing them to store energy before quickly releasing it. Like a snap of fingers.
Referencia: R. Acharya et al. The ultrafast snap of a finger is mediated by skin friction. Journal of the Royal Society Interface. Published online November 17, 2021. doi: 10.1098/rsif.2021.0672.