Millions of computers around the world know this instant as 1234567890.
Unix-based systems store time as the number of seconds elapsed since January 1, 1970. This is called the Unix Epoch Date. Do the math, and at 23:31:30 UTC today that works out to 1,234,567,890 seconds. Pretty neat!
Of course, there’s danger lurking here: generally, we use 32-bit signed integers to store the number of seconds. A 32-bit signed integer can only store numbers up to 2,147,483,647 or so. Do the math again, and you’ll arrive at another neat date: January 19, 2038. On this day, shortly after 3:14 AM UTC (conspiracy theorists take note: why is this Pi?), the world ends. Planes drop from the sky, bank machines spit out cash non-stop, and nuclear bombs detonate, just like they did at midnight on January 1st, 2000. Awesome!
January 1, 1970 isn’t just the Epoch Date for UNIX. A few other trivial systems use this date, as well. You may have heard of some of them:
- Mac OS X
Man, oh man, will that a good day to be a Windows guy. Of course, exactly ten years later DOS, FAT16, FAT32, and OS/2 all explode. Hopefully by then we’ll all be using managed code: .NET bases dates around January 1, 1. That’s 1 AD. Presumably, they have this 32-bit unsigned integer problem sorted out.