What in the world do lava lamps have to do with internet security? It about random numbers, because unpredictable sequences of numbers is crucial for proper encrypting. Machines aren't good at generating random numbers, because we design our technology to be as predictable as possible, lest we trigger a robot uprising. However, flowing liquid is about as random as you get. An entire wall of lava lamps moving colored liquid around is is unpredictable enough to generate random numbers.
Learn how it's done with Tom Scott, who is still in California finding us interesting things to learn about. This report is from Cloudflare in San Francisco.