Around two years ago, physicist Scott Waitukaitis came across a story on IFLScience about a guy putting hydrogel balls into a frying pan, causing a truly bizarre reaction. The moment the gel balls hit the hot surface, they wildly jumped up and down, letting out a strange screeching noise (original video below).
Confused about what was going on in the video, he decided to find out. Two years on and the research is now published in the prestigious journal Nature Physics. It even managed to land the front cover of the November 2017 issue.
“I actually remember first seeing the video. It was around December 2015 and I was just sitting at a science conference in Chile,” Scott Waitukaitis, lead study author, told IFLScience. “I’m really bad at conferences. If I go to a talk and I don’t get excited, I go on my phone”
“So I was just scrolling through Facebook during a talk and I came across a post on IFLScience. I clicked the link, watched the video, and immediately I was thinking: ‘What the hell is going on here?'”
“After a good couple of days of looking around, I realized no one had studied this before and that I was looking at a new kind of physical effect,” he added.
Scott and a team from Universiteit Leiden in the Netherlands discovered it’s a new type of Leidenfrost effect that occurs with soft solid materials, which they have now called the “elastic Leidenfrost effect”.
The original Leidenfrost effect is the physical phenomenon you see if you chuck some water droplets on a frying pan. If the hot surface is significantly hotter than the boiling point of the droplets, a little hovercraft of insulating vapor stops the drop from physically touching the hot surface.
The “elastic Leidenfrost effect” is similar to that. Using a high-speed camera, the team observed that the gel-like balls create vapor when introduced to the hot surface, much like the water droplets. This basically sparks a feedback loop. When the balls create vapor beneath them, it deforms and squishes the gel ball. In turn, this allows more vapor to escape from underneath. This quickly creates a rippling gap under the ball that opens and closes thousands of times a second – and results in a lot of bouncing and screeching.
You can watch the elastic Leidenfrost effect in the video from the researchers below.
Scott also got in contact with “Johnny”, the Ukrainian YouTuber and rapper who first filmed the video and originally inspired the study. After chatting for a while on Facebook, Johnny explained how he simply made the video for the purposes of going viral, along with a bit of child-like curiosity.
“It was an uninhibited way of trying new things – it’s a good skill. I think science can benefit from it a lot,” added Scott.
“I’m a big fan of science democratization and that’s why I like this project so much. With technology, you can start with a guy goofing around in Ukraine, the right eye sees it in the US, it gets passed on, then onto IFLScience, then we write a scientific paper on it!”