They could make it difficult to open up the camera and extract its signing key, but only one person has to do it successfully for the entire system to be unusable.

In theory you could have a central authority that keeps track of cameras that have had their keys used for known-fake images, but then you’re trusting that authority not to invalidate someone’s keys for doing something they disagree with, and it still wouldn’t prevent someone from buying a camera, extracting its key themselves, and making fraudulent images with a fresh, trusted key.

Most currencies have a special pattern that printers are programmed to detect and refuse to print. Since illegal gun part designs can’t be forced to include a marker declaring that they’re gun parts, a 3d printer would have to 1) know what a gun is, 2) know how a gun works, 3) be able to tell whether any particular shape could be used as part of a gun, and 4) be able to tell whether any particular shape could be cut and reassembled into a shape that could be used as part of a gun

The primary reasoning I’ve heard is that it’s easier to do arithmetic with numbers that are factors of your numeral base and 12 has more factors than 10 (1, 2, 3, 4, 6, 12 vs. 1, 2, 5, 10)

Base 12 seems a little impractical to me since humans have 10 fingers, which makes base 10 easier to teach to children, but it’s a matter of opinion i guess

τ is equal to 2π, which allows the formula for the circumference of a circle to be written more concisely (τr vs. 2πr or πd) but complicates most other places where π is used, like in the area of a circle (τr^2/2 vs. πr^2)

Maybe browsers could be configured to automatically accept the first certificate they see for a given .internal domain, and then raise a warning if it ever changes, probably with a special banner to teach the user what an .internal name means the first time they see one