Why is 11 am and 1 hour == 12:00 pm?(ell.stackexchange.com) |
Why is 11 am and 1 hour == 12:00 pm?(ell.stackexchange.com) |
11:59:59.9999999999 is still AM.
12:00:00.0000000001 is clearly PM.
When should the AM switch to PM? My intuition says at the same time that the 11 switches to a 12 (and all the 9's switch to 0's). Thus, noon is pm.
Having said that, in reality the solution is banish the abominable 12 hour clock, and use the 24 hour clock.
That also removes the ambiguity whether "Midnight on January 1st 2017" means 2017-01-01 00:00 or 2017-01-01 24:00 == 2017-01-02 00:00.
"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!
Maybe in the stackoverflow answer we're discussing here? :-)
Given that, to you claim, 11:59.59.99999[...] is still AM, then 11:59:60 is still AM, thus 12:00:00 is still AM.
[0] https://www.youtube.com/watch?v=SDtFBSjNmm0
/s
I'm arguing for switching the very moment the number of nines is infinite, or, in other words, they've turned into (an equally infinite number of) zeros.
That's how I remember it anyway :)
Pop quiz: How many hours passed between 11am and 12am?
The one from your current timezone, obviously. And if you omit your timezone, you obviously mean your current timezone; the one you're residing in. If you're in Paris and you tell your kid dinner is at 6 PM then you mean local time. If your kid then comes home at 7 PM and says oh I thought you meant UK time then that's obviously your kid being a smartass. Even if you are both from UK. Why? Because it isn't practical to stick to a timezone you're not residing in.
Wether we're talking about 6 PM or 18 and 7 PM or 19 makes zero difference to your argument.
24H notation is just simpler and more practical. You don't have to resort to keyboard, it even takes up less space, and most importantly the context is less relevant ie. if AM/PM is omitted you still know what's up.
The only reason people stick to 24H notation, or imperial system for that matter, is "because we've always done it like this" ie. an argumentum ad antiquitatem. Not because it is better. Backwards compatibility comes with a price. You should always question whether the price is worth it.
I can think of one problem with the 24H system: analogue clocks like watches and churches. They use 12 hours. But when you watch that, that's communication to you as a human instead of human to human. And you know whether it is morning or evening, day or night, unless you're in a truly strange mental state.
This is especially important in language, where in some cultures the word 'tonight' actually translates to what you'd call 'last night' in English, for example.
Doesn't matter. Anything would be arbitrary. Just pick one and be done with it, and we already have GMT and UTC.
thats a damn long day. my day is only from 00:00:00 to 23:59:59. where do you live that you have 25 hour days? /s
I guess the 24-hour system leads to confusion, too..? ;-)
Imagine this dialogue:
TOM: Oh good, it’s time for lunch!
JERRY: Oh really, and how do you know that?
TOM: Because it has to be noon, since I just now didn’t hear the clock!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.
Most kids in the US are taught that 12 PM is noon and 12 AM is midnight in elementary school. Though many understand this by first grade, I have been surprised to encounter native English speaking 40+ year old adults that still do not remember this. "Meet me at lunch at 12 AM!"
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.
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.
Do Spanish-American (and others) use kilos, metres, Celsius and all the rest? I'd assumed not, since the Quebecers I know use American measurements for their body and cooking. But I'd like to be wrong.
(You could also have meant anglophone, but that's too broad. 23:05 is fully understood in Britain, and the normal way to write the time on timetables and so on.)
"As of 2017, seven countries formally do not use the metric system as their main standard of measurement: the United States, Myanmar, Liberia,[3] Palau, Marshall Islands, the Federated States of Micronesia, and Samoa.[4] However, both Myanmar and Liberia are reportedly essentially metric, even without official legislation."
I tried various things like if a meeting says 12AM, subtract one day, but then I'd encounter edge cases like meetings that start at 12AM now showing the previous day, or meetings that are scheduled from 12AM on the 8th to 12AM on the 8th (basically zero-minute durations) showing the wrong day or a bunch more things you don't think of until you try to develop applications for end users you might never talk to.
Eventually I set it to make any meeting that ended at 12AM just subtract one minute from the overall duration so it would end at 11:59PM instead. It didn't as much solve the problem as it did just avoid it, but at least people stopped complaining.
Doing it right is really hard.
Whether this is measuring time or calculating time, it's hard.
It would be pronounced "twelve hundred hours" by the automated announcement systems, and 12 o'clock by people.
Example of leaving at 5:00 (a minute in) https://youtube.com/watch?v=0cg-n-GF38E
00:01 is announced as "midnight oh one". ("The train on platform nine and three quarters is the midnight oh one service to Hogsmeade, calling at Hogsmeade only. A buffet trolley of drinks and light refreshments is available on this train.")
My observation, at least where I live, is that both systems are used in practice. Especially at grocery stores, where the aim seems to be intentional confusion. For example you buy oranges listed for 2.34 a pound, but at the register you are charged 5.74 a kilo. Where you charged the correct rate? Maybe? Maybe not?
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".)
12:00 noon is neither AM nor PM, and there'se no confusion.
The real question is why is the hour after midnight 12:01-12:59 AM.
Anyway, the real answer is that 0/12 and 13/1 are partial branch cuts and that "12" is used because "0" is awkward for mundane reasons, but retains some of its "0-ness"
Any potential for confusion results from an ancient decision to designate noon/midnight as 12:00. If they had simply made them 1:00 instead then there'd be no trouble today.
In 1998, the Swiss watch company Swatch introduced the concept of a decimal Internet Time in which the day is divided into 1000 'beats' so that each beat is equal to 1 minute 26.4 seconds. The beats were denoted by the @ symbol, so that, for example, @250 denotes a time period equal to six hours.
So far this system has not caught on
http://www.abc.net.au/science/articles/2011/11/15/3364432.ht...
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 (e.g. London) is around 19:00 (7pm). If you live in California you know that diner around your parts is around 03:00 (3am).
If you're in different countries, e.g. one is in London and the other is in California, "Let's have a Skype at around 11:00" is unambiguous -- it will be 11:00 at both your clocks.
Lastly, if you're in different countries and you want to call someone in California, and wonder whether now (11:00 GMT) is a good time, you just have to know the offset number (the sun rises there 8 hours later) which is the same as knowing the timezone.
Without timezones, it's only knowing the "part of the day" (whether it's late or dusk or sunrise time etc) in another place that requires knowing an offset (similar to knowing the timezone offset today).
All other calculations and coordination is vastly simplified.
>(e.g. "Let's have dinner Wednesday night" would be very confusing in some parts of the world. "Is that the Wednesday night just after Tuesday night? Or the one just before Thursday night?")
How is that confusing? Assuming we're talking about dinner, it would have to be dinner time in the place those people live. So, e.g. a little before or after sunset time on Wednesday. Whether that corresponds to 7pm or 2am or 12pm, people will know when it's that time where they live.
You waive off my dinner example as if "dinner" is a rigid set time. It's not. I'm in New York and I eat dinner at 6pm sometimes. Other times I eat at 8pm. Under UTC, this means that I sometimes have dinner on Wednesday at 23:00 and other times I wait until Thursday at 01:00. Asking someone over for "dinner on Wednesday" would always be ambiguous.
Here are some other confusing examples, if the dinner one doesn't illustrate it:
(At work)
"What days do you have off this week?"
"I got Tuesday/Wednesday and Friday/Saturday off"
"When is the paper due?"
"Tuesday"
"The class that starts on Tuesday or the
one that ends on Tuesday?"
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). So I don't see the gain here. Dealing with time differences is a fundamental aspect of living on a ball Earth.
I mean there is no standards committee for this, but that's what common convention tells us in the Anglophone part of the world.
I've often enough seen "1st January 2017, 11:59 pm" or, even worse, "1st January 2017, 12:01 am" for deadlines etc.
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.