#year 2038 problem

Caine: "Kinger, I have terrible, terrible news! It's almost 2038, and we're on a 32 bit system!"

Kinger: "Oh God, will the date mismatch scramble our mind files?"

Caine: "Worse! We'll all get DECADES worth of reverse jet lag!"

Pomni: "What date are we gonna be reset to?!"

Caine (dramatic echo): "January 1st, 1970!"

They are all suddenly dressed like hippies.

Firstly, i'm not an expert by any means. If you wanna read about it in detail there's a great wikipedia article here

But in essence, many systems store the current time by keeping track of how many seconds it has been since the 1st of January 1970 (UTC), a system known as Unix time. The issue here is in how the number is stored. Because this value is saved in the 'signed 32 bit integer' format, the maximum value before things get weird is 2^31-1, or 2,147,483,647. On January 19th 2038 the number of seconds since 1/1/1970 UTC will go over 2,147,483,647. Due to some weirdness in how we use binary, this will turn it into -2,147,483,548. That means all of these systems will think it's ~68 years *before* 1970, and they'll jump alllll the way back to thinking it's December 13th 1901.

The reason that's a problem is because *many* things are linked to the time. Like for instance a backup system that only keeps the three newest backups. If the most recent backup is labelled as being from 1901, it'll just delete it in favor of the ones from 2038.

Here's a gif I stole from that wikipedia article showing what would happen. That first binary 0/1 represents positive/negative.