I recently encountered a list of “Falsehoods programmers believe about time.” With the possible exception of the one about black holes (third from the end), they’re all false.

“There are always 24 hours in a day”? Not when we “spring forward” to Daylight Saving Time; that day only has 23 hours. Likewise, when we “fall back” to Standard Time, that day has 25 hours. Of course, even those rules aren’t true if you live in a region that doesn’t observe Daylight Saving Time.

Even Google has trouble with this. Monday morning, at 9:07 AM Eastern Daylight Time, I asked Google what time zone Colorado is in. The response was Mountain Time, which is what I was expecting.

Google then offered a little extra information. In Maryland, it was 9:07 AM Monday morning. But in Colorado, according to Google, it was 8:46 AM on Sunday.

That time zone offset is a bit more complicated than I expected!