Sometimes it takes the power of the internet to bring to light some of the simplest yet most impressive scientific phenomena. Case in point: a recent clip of a “fluidized bed” of sand acting like liquid that has been trending on Reddit.
Check it out and prepare to get nerdy.
Nope, you’re not tripping; that is indeed dry sand flowing and bubbling like liquid. So, what exactly is going on here? Because, we assure you, there is no liquid in this mix, just air being shot up from underneath the sand.
“The difference between solids and liquids can be boiled down to the space between the particles, so when you have something that’s liquid, you have a lot of space between the particles that allows it to move freely,” says Walter Stoddard, Research Programmer at the Ontario Science Centre.
“By blowing the air in and around these sand particles, it creates this cushion of air around them so now they’re free to float and slide and flow between and around each other. It’s the reduction of internal friction–with that friction much lower, the particles are able to flow and that flowing resembles a liquid.”
Neat, right? For a little more insight, here’s a video explainer from The Royal Institute with some great vintage assets from their vaults.
Clearly this isn’t a new trick–that vintage footage wasn’t even shot in colour–but it’s taken the magic of the moving, looping picture (aka the Gif) to bring it to the attention of the masses.
Well done, science. And bravo, internet. You two make a great team.