The lava lamps that help keep the internet secure

At the headquarters of Cloudflare, in San Francisco, there’s a wall of lava lamps: the Entropy Wall. They’re used to generate random numbers and keep a good bit of the internet secure: here’s how.

I love Tom Scott’s videos and this method Cloudflare uses is pretty cool.



  • John Kordyback

    I’ve heard of radioactive sources, like their Singapore office, but I’ve never heard of pendulums and lava lamps. Random and aesthetically pleasing. Tip o’ the cap.

    • brucej

      They used to sell add-in cards that were essentially geiger counters for use as true random number generators. There may have even been Apple ][ versions and I know there were IBM PC cards for this purpose; I remember seeing them for sale back when Computer Shopper was an inch-and-a-half thick tabloid-sized slab of newsprint…

      • John Kordyback

        That is pretty cool. I never saw those but it appeals to the statistician in me. Thanks!

  • brucej

    Aeon’s ago, when the intertubes were young, Usenet was gnarly and the web was this slimy thing flopping on the beach learning to breathe air in Bern, there was ‘Lavarand’… https://web.archive.org/web/19971210213248/http://lavarand.sgi.com:80/