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Today the xkcd: Y2K and 2038 comic was published and this reminded me of the recent very good technical blog post Time is an illusion, Unix time doubly so... from Jan Schaumann where he explains how time is handled on different operating systems including some historical background.
A famous scientist and adventurer once said: 'time is not linear but something like "Wibbly Wobbly Timey Wimey"'. He has since been proven more correct than he ever imagined.
As you well know, on Unix systems we measure time as the number of seconds since "the epoch": 00:00:00 UTC on January 1st, 1970. This has made a lot of people very angry and been widely regarded as a bad move.
For starters, this definition is not based on something sensical such as, say, the objective frequency of vibration of a Cesium-133 atom, but on a convenient fraction of the time it takes a particular large rock to complete a full rotation around its own axis.
If you want to learning about any of this:
- Initially the time was measured in 1/60ths of a second
- At least one country has two different utility frequency
- Why Linux will fail again on 23rd April 2262 even with 64-bit counters
- How different operating systems behave around the beginning or end of the epoch
- What will happen with positive or negative leap seconds
then click here and read this fine blog posting.
Happy reading and learning!
(Score: 2) by Thexalon on Monday November 14 2022, @09:12PM
Division, yes. Fractions, no.
Let's say for your example problem there are 16 apples. We want to divide them evenly between two people, that's pretty easy: You put 1 in my pile, 1 in your pile, repeat until you're done. And you count both piles of apples to make sure they're the same.
Now let's make it 17 apples. We'll do the same thing, but we'll notice that 1 of us has 1 more apple than the other. So we'll pull that out and make a new plan for that one. (i.e. discovering the concept of a "remainder").
It's a bit of a leap to get from that to "OK, maybe we can cut the extra apple perfectly in half". And even more to generalize that if we are divying up among 3, 4, 5, etc people. And there's some interesting stuff to think about when you're trying to treat 4 quarter-apple pieces as the same as 1 apple, which they kinda are but kinda aren't.
And it gets even harder to arrive at that solution when you're divying up goats rather than apples.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.