Help me with American time notation

General Questions
#21

I think Priceguy’s just going to say “to hell with it.”

But, while Ebola Gay’s strictly correct, there are conventions. Every single digital clock or watch that I’ve even seen shows the minutes in this sequence: 11:59pm; 12:00am; and 12:01am. Similarly pm sequences thus: 11:59am; 12:00pm; 12:01pm. The Windows and Macintosh clocks exhibit this behavior, too. This makes sense sequentially. The 00 minutes is the first minute, because 00 minutes 1 second is within the domain of the first minute. Oddly, this is just the opposite of my Y2K belief (I celebrated the 21st century a year later than most people).

Now for midnight, if I were to say, “tonight at midnight” I would mean tonight just after 11:59pm. This is really a colloqialism on my part, since I would also say next Tueday at midnight I would also mean just after 11:59 on Tuesday. But were I to say 12:00am on Tuesday, I would mean the midnight between Mon. and Tues. Actually I know this causes confusion depending on whom I’m talking to, so I’m usually more verbose and then say something like at 12:00 am Monday night Tuesday morning just to be clear.

#22

I think Priceguy’s just going to say “to hell with it.”

But, while Ebola Gay’s strictly correct, there are conventions. Every single digital clock or watch that I’ve even seen shows the minutes in this sequence: 11:59pm; 12:00am; and 12:01am. Similarly pm sequences thus: 11:59am; 12:00pm; 12:01pm. The Windows and Macintosh clocks exhibit this behavior, too. This makes sense sequentially. The 00 minutes is the first minute, because 00 minutes 1 second is within the domain of the first minute. Oddly, this is just the opposite of my Y2K belief (I celebrated the 21st century a year later than most people).

Now for midnight, if I were to say, “tonight at midnight” I would mean tonight just after 11:59pm. This is really a colloqialism on my part, since I would also say next Tueday at midnight I would also mean just after 11:59 on Tuesday. But were I to say 12:00am on Tuesday, I would mean the midnight between Mon. and Tues. Actually I know this causes confusion depending on whom I’m talking to, so I’m usually more verbose and then say something like at 12:00 am Monday night Tuesday morning just to be clear.

#23

This is so not my fault. I really thought this was a simple question. Unfortunately I cannot, as Balthisar suggests, say “to hell with it”. I need to know.

Is it really the case that we have here a system of time notation whose users don’t agree on how to use it?

#24

Well at least we all agree that when someone says 12 a.m., it means some midnight.

To me, midnight Saturday has to be at night on Saturday. Saturday night starts when the sun goes down and lasts until sunrise, so it includes several hours that by official calendar time are on Friday. But it’s still Saturday night.

#25

No – everyone knows how to use it. It’s just that the wee hours of the morning are by nature ambiguous because the day doesn’t change when a person wakes up.

–Cliffy

#26

Just for the sake of reiterating what a few other people have said, midnight (or 12 AM*) Saturday means the 12:00 between Friday and Saturday in every application I’ve ever seen. In a lot of cases people try to avoid confusion by saying either “11:59 PM Friday” or “12:01 AM Saturday”, or use the between-X-and-Y formation to make themselves clear.

  • Yes, the exact instant of midnight isn’t AM or PM. But since every picosecond after 12:00 M is AM, calling it 12:00 AM works for me.
#27

:sigh: I mean “Sunday” instead of “Friday,” of course.

#28

I’ll just let the folks at Greenwich speak for me:

http://www.nmm.ac.uk/site/request/setTemplate:singlecontent/contentTypeA/conFaq/contentId/78

#29

Well at least we all agree that when someone says 12 a.m., it means some midnight.
Nope. You can find examples of people using 12 AM for noon, and 12 PM for midnight.

Is it really the case that we have here a system of time notation whose users don’t agree on how to use it?
Yep. If someone says “noon” or “midnight,” there’s no question of the meaning. But many folks insist on using “12 AM” and “12 PM,” which technically are undefined and thus nonsensical. There are conventions, but there are not consistent, universally applied conventions, and thus it is not possible to be CERTAIN what the speaker/writer meant.

#30

Then how the freaking flying fuck can an online game (with an international audience, no less) use 12am and 12pm without further explanation?

Oh well. Here goes an email to support.

#31

12 am doesn’t, in the original nomenclature, formally exist. At either of the possible Twelves it is neither “ante” nor “post” meridian, it is simply “meridian”. 12 is necessarily either midnight or noon but neither AM nor PM. Obviously that would be grossly awkward in the era of digital timepieces and time stamps and whatnot, so some convention had to be adopted, but I’m not surprised it isn’t widely shared.

The whole works is a hideous anachr umm OK poor choice of words, but it’s a dinosaur. Numbers that reoccur twice in a day’s time span distinguished by AM and PM. These numbers over here go up to 60 and then increment the next column over by one (under most circumstances) and go back to 0. These numbers on the other hand do it by 12 and then start over, but the day doesn’t roll over to the next day until it does it twice. Oh, and we’re starting off at 12, doesn’t that seem like a good number to start off at?

Personally I’ve always wanted to see us go to decidays and centidays and millidays. Specify the day of the year, stick a decimal point, and stab on the decimal equiv for how deep into the day you are. Add 317 millidays and you either did or did not end up in the next day and any dime store calculator will tell you which in one easy operation.

Other people defend the wonderfulness of 60 and the brilliance of Babylonians and how nice it is to have a quantity that splits evenly into quarters, thirds, fifths, sixths, twelvths and halves. Fine, then let’s split the day into 60 equal parts and each part into 60 and each of those into 60, at least we can get rid of stupid AM and PM and hours that are bigger chunks of days than minutes are of hours and all that. And if we’re going to do 60s let’s convert the whole counting system to 60s, it’ll convert adequately well to hexadecimal and then all our commonly measured things will divide nicely by quarters, halves, thirds, twelfths, etc., why limit the advantages to the measurement of time?

#32

NIST says that noon and midnight have no am or pm designation.

However, I think most people (the rational ones, in my opinion) take “12 AM” to be midnight, and consider it to belong to the following day. After all, at precisely midnight, when the hour digits flip from 11 to 12, it makes sense that that’s when they should be flipping from PM to AM and from Friday to Saturday. Otherwise, you have some unspecified amount of time (based on the precision of your measurement) where it’s changed from 11 to 12, but it hasn’t yet changed from AM to PM or from today to tomorrow.

Unqualified, if someone says “midnight Saturday” to me, I ask for clarification, because people aren’t consistent in the way they use it. It’s common for people to say things like “Saturday night at 1am,” which is obviously technically incorrect, but it’s why you’d assume “midnight Saturday” is Saturday night, even though technically it’s not. Because of this, I would always specify “saturday night at midnight” or “sunday morning at midnight” (they mean the same thing to me for casual usage).

#33

Why is Midnight 12 AM?

Because by the time you finish saying “Hey, it’s 12 AM,” it’s already 12:00:02 AM.

:slight_smile:

#34

As a person who experiences 12 midnight in the middle of my “day”, I think my opinion on this subject is worth at least 5% more than any of your diurnal opinions. :wink:

12:00 AM on Friday is at the beginning of the day. My digital watch tells me so: right after THU 11:59:59 PM, it switches to FRI 12:00:00 AM.

Midnight on Friday, however, is at the end of the day. If someone says “come by on Friday at midnight”, I’ll be there sometime between FRI 11:50 PM and SAT 12:10 AM, because I’m leaving on Friday and arriving around midnight. Midnight on Friday is in the middle of Friday night, which starts on Friday and ends on Saturday.