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Why is 11 am and 1 hour == 12:00 pm?

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Re: Why is 11 am and 1 hour == 12:00 pm?

#61

Post by bradknowles »

freehunter wrote: post #46
makecheck wrote: post #8

You’ll probably never see a flight or a movie or something start right at 12:00; it’s just so much clearer at a glance to see that 11:55 AM/PM.

A while back I wrote a calendaring application where I encountered a similar problem and came up with a similar solution. If someone scheduled an all day meeting that ended at 12 midnight, the calendar would show it as a two-day meeting. The meeting started at 12AM on January 8th and ended at midnight of the same day... but since January 8th ends at 11:59PM and January 9th begins one minute later, the invite would ro…

Time is hard.

Doing it right is really hard.

Whether this is measuring time or calculating time, it's hard.

Re: Why is 11 am and 1 hour == 12:00 pm?

#62

Post by Dylan16807 »

AnimalMuppet wrote: post #55
kbutler wrote: post #44

The instant it becomes noon, it is no longer ante meridian (before noon). Thus we have to make an arbitrary allocation, and it makes a lot more sense to lump 12:00 with 12:01-12:59, rather than with 11:00-11:59.

No it doesn't. It makes exactly the same amount of sense to put 12:00 with 12:01 as it does with 11:59, because noon is not post meridian in exactly the same way that is not ante meridian.

> because noon is not post meridian in exactly the same way that is not ante meridian.

That was already implied. I think you're confused about what kbutler was stating. The full argument goes like this:

1. by itself, 12:00 is not post meridian

2. by itself, 12:00 is not ante meridian

3. therefore we must choose which label to use on other merits

4. without 1 or 2, it makes more sense to lump it with the time that's a single digit off by one, and not the time that's many digits off by many

---

On top of that, for 100.0000% of the time the clock reads "12:00" around noon, it's PM. Even if you defined the moment of noon to be AM, it would be impossible to ever catch a clock saying 12:00 during the final moments of AM.

Re: Why is 11 am and 1 hour == 12:00 pm?

#63

Post by naikrovek »

mark-r wrote: post #49
naikrovek wrote: post #11

Earlier quoted context omitted.

I believe the actual answer is that there is no 12:00 AM or PM. You're meant to say "twelve noon" or "twelve midnight" rather than AM or PM for this exact reason. "actual answer" is maybe a bit strong - I read it somewhere but I can't remember where. The site or book or wherever it was that I read that did seem quite authoritative on the matter, however!

That's just a cop-out. If you change the question from 11 AM to 11:01 AM it's still just as valid, and there's no need to argue about the ambiguity. Is there anybody who would seriously argue that 12:00 AM plus one minute should be 12:01 PM? That way lies madness.

12:00 isn't AM or PM. It straddles them, and isn't wholly either one because of it. That's what this is about. Some people could argue that noon is 12AM. Others can argue that it's 12PM. Both views have merit, and despite that, we need to agree on one or the other, because times are often written down and everyone needs to know what time is meant when someone writes "12AM." Since consensus on this has never been achieved, we just decided on something that people COULD agree on: noon and midnight.

The question isn't valid for 11AM vs 11:01AM, because crossing into 11:01AM doesn't put you into the afternoon like 12:01PM does. It's only a valid question at the transition time between AM and PM or vice versa. So, it was decided a LONG time ago to just skip the problem and say "twelve noon" or "midnight" (or "twelve midnight".)

Re: Why is 11 am and 1 hour == 12:00 pm?

#64

Post by romanovtexas »

Fascinating. I've seen that at a lot of shops and places in Japan they go beyond the 24 hours – indicating continuity in a way.

For example of a shop is open in the pattern –

Monday, January 8th 21:00 till Tuesday, January 9th 02:00

The Japanese signboards will denote it as -

Open on Monday, 8th Jan 21:00-26:00

I think it's we quite convenient and let's the people know that the shop's time pattern sort of carries on from the previous day onto the next.

Re: Why is 11 am and 1 hour == 12:00 pm?

#65

Post by SllX »

FabHK wrote: post #39
SllX wrote: post #36

Earlier quoted context omitted.

Friday Midnight is the same as Midnight Saturday Morning. I mean there is no standards committee for this, but that's what common convention tells us in the Anglophone part of the world.

Is "midnight 1st January 2017" unambiguous? Would it be in a legal document? I've often enough seen "1st January 2017, 11:59 pm" or, even worse, "1st January 2017, 12:01 am" for deadlines etc.

Would you rely on common conventions in a legal document rather than legally defined terms?

Re: Why is 11 am and 1 hour == 12:00 pm?

#66

Post by coldtea »

function_seven wrote: post #58
coldtea wrote: post #56

Earlier quoted context omitted.

> Sorry if I misinterpreted your response, but do you think doing away with timezones in "normal" life would be a net gain? I think it would add way more confusion than it would eliminate. It's the exact same information needed both today and after doing away with timezones. If you're in the same place as the other person, there's no confusion at all. If everybody uses GMT, you know e.g. that diner around your parts…

What are we trying to solve by moving the world to UTC? We can't change when the sun rises and sets, nor can we change our circadian rhythms. So what we're left with is the fact that different parts of the world do things at different times. Using timezones, we set the start, midpoint, and end of the day to common numbers. If we ditch timezones and move to UTC-everywhere, we still have timezones. They're just implici…

>We could acclimate to all of this, sure. But we'd still have timezones. It wouldn't be immediately obvious to the Londoner that 11:00 is a terrible Skype time for her California colleagues (3am)

Yeah, I addressed that though. We'd still need to know the offsets sunrise-wise or cultural-wise (e.g. 10pm is late to call in some countries, absolutely normal in others).

>So I don't see the gain here.

It's trading local time reference points (like the sun etc), for global coordination (in an increasingly interconnected and real-time planet) -- so everybody immediately knows what time X is everywhere. It's not meant to eliminate the fact that sunrise times etc are different, just to keep a stable frame of reference without timezones for time (one would still need the offsets to know whether it's night or day in place Y at time X).

>Dealing with time differences is a fundamental aspect of living on a ball Earth.

Doesn't mean there's one and only one way to deal with those though. Or that people don't spend a lot of time in the real-time, non-spherical, always-on, web too nowadays.

Re: Why is 11 am and 1 hour == 12:00 pm?

#67

Post by kbutler »

AnimalMuppet wrote: post #55
kbutler wrote: post #44

The instant it becomes noon, it is no longer ante meridian (before noon). Thus we have to make an arbitrary allocation, and it makes a lot more sense to lump 12:00 with 12:01-12:59, rather than with 11:00-11:59.

No it doesn't. It makes exactly the same amount of sense to put 12:00 with 12:01 as it does with 11:59, because noon is not post meridian in exactly the same way that is not ante meridian.

If it were just

11am 12am 1pm

That would make sense.

But it would be

11:59:59.9999999999am

12:00:00.0000000000am

12:00:00.0000000001pm

So incrementing the arbitrarily least significant unit would require toggling the most significant unit with no other digits changing.

And if you ever saw a clock displaying 12am, it should actually be p.m. by the time the light reached your eye.

Makes more sense to increment the a to p at the same time you roll over all those 99s and 59s to 0, then 12 is consistent however precise your clock is.

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