Ant farm ? Hamster wheels ? Anything critter-driven should provide some entropy.

I once read that noise of camera in total darkness is apparently a good source.

The noise probably makes the lava lamp wall just as effective as pointing the camera at the Mona Lisa - the lamps themselves are not that unpredictable frame-to-frame.

For the record, the lamps and camera are present in their lobby afaik, so you can actually go there, stand in front of them, and slightly affect the entropy.

A cool parlor trick, certainly.

You can already have a good entropy source from a single resistor.

https://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise

This is what gets me - entropy is hard, but not that hard. I get it goes against everything a computer is built to do, but so does telling time.

Would a CRT TV tuned to channel 3 and no RF input be a good source?

In the sense that RF noise can be a source of entropy: Sorta*. But one doesn't need the whole thrift-store television set to do that; the visual aspect of a CRT displaying analog video snow just adds style points**.

*: Sorta, because if someone discovers that the entropy is derived from an analog TV tuned to channel 3, then they also know how to influence it from outside.

**: Style points can have value; it's OK to have fun with work. But that's a secondary function.

I imagine that there might still be a way to swing by with RF equipment and tip the scales in your favor. And if you're important enough, I'm sure there'll be someone motivatd enough to do this. After all, Polymarket was motivating enough for someone to take a hair dryer to a weather station...

https://www.theguardian.com/world/2026/apr/23/hairdryer-or-l...

better to just switch to... random channel every while :) Not perfect but something.

https://www.random.org/ Uses atmospheric noise. These dudes use dice? https://youtube.com/shorts/ncoDq5EcPFg?si=lI6f9cw8dWcaDZ4Y

Speaking of ants, Fourmilab (i.e. John Walker, of Autodesk fame) used to provide a random number generator powered by background radiation: https://www.fourmilab.ch/hotbits/

Yes, they also have wave machines, pendulums, and mobiles :)

https://blog.cloudflare.com/harnessing-office-chaos/

https://blog.cloudflare.com/chaos-in-cloudflare-lisbon-offic...

Wouldn’t thermal noise in a resistor make more practical sense?

I prefer cosmic microwave background radiation (CMBR) as my RNG of choice

until someone uses microwave lol

The original from SGI back in the mid 90's, before CPUs had RDRAND instructions etc... was a an actually practical solution.

At the time I was at the Internet company that originally got online-gaming banned in the US, we were looking at CCDs and Cesium emitters that required a license etc...

While I am not sure, it seems cloudflare basically implemented one after SGI's[0] patent expired.

The patent and the licensing cost and adding SGI was a major blocker for us doing it, the startup closed before we found a real solution. But the best PRNGs like Blum Blum Shub were way too slow at the time. But things did improve quickly at that time.

[0] https://patents.google.com/patent/US5732138A/en

SGI was pretty amazing. I know some folks who worked there - Cray too. There’s a loyalty that just doesn’t exist any more - and arguably isn’t earned anymore.