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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?

#51

Post by merb »

JacobJans wrote: post #43
FabHK wrote: post #31

Earlier quoted context omitted.

Wikipedia: "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." https://en.wikipedia.org/wiki/Metrication

Formal use is different that widespread consistent use, excluding the other system. 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?

well in germany you still say "ein pfund" (one pound) or "halbes pfund" (half pound) if you buy sausages/meat. but you mean 500g and not the real value of one pound. it's just that this is used because we got used to it. we also have a wierd system for the clock where we say "viertel vor" (a quarter to) or "viertel nach" (a quarter past). which is pretty common to say the time in quarters instead of values.

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

#52

Post by goialoq »

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.

AM means "before noon". PM means "after noon"

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"

https://en.wikipedia.org/wiki/Branch_point

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

#54

Post by nkkollaw »

ktpsns wrote: post #2

I don't want to be offensive, but this is just another example where anglo-american standards for time and length measurements are ill-defined and lead to confusion. Instead, we have the SI system for the rest of the world and we have international standards for counting time -- with time going from 00:00:00 to 24:59:59 a day. I wonder why people refrain to adopt a working system in favour of culture. I never underst…

> with time going from 00:00:00 to 24:59:59 a day

I guess the 24-hour system leads to confusion, too..? ;-)

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

#55

Post by AnimalMuppet »

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.

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

#56

Post by coldtea »

function_seven wrote: post #23
coldtea wrote: post #15

Earlier quoted context omitted.

> But whose 24 hour clock? Should we all be on GMT? That's arbitrary and eurocentric. Doesn't matter. Anything would be arbitrary. Just pick one and be done with it, and we already have GMT and UTC.

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. (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?")

>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 (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.

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

#57

Post by imustbeevil »

fallingfrog wrote: post #50
FabHK wrote: post #5

I thought continuity provides an answer: 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 J…

That's true for every hour though. The same argument applies to 10:59:59.99999 and 11:00:00 Pop quiz: How many hours passed between 11am and 12am?

The point is that a nanosecond after noon is "post meridiem".

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

#58

Post by function_seven »

coldtea wrote: post #56
function_seven wrote: post #23

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. (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?")

> 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 implicit now. And we also have the new burden of our day changing while the sun is still up.

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"
(At school)

    "When is the paper due?"

    "Tuesday"

    "The class that starts on Tuesday or the 
    one that ends on Tuesday?"
There's a reason we have the days change when most of us are asleep. It's a lot easier. A day encapsulates a day.

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.

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

#59

Post by mark-r »

goialoq wrote: post #52
mark-r wrote: post #49

Earlier quoted context omitted.

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.

AM means "before noon". PM means "after noon" 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" https://en.wikipedia.org/wiki/Branch_point

I'm not disagreeing that "noon" or "midnight" are less confusing, I'm simply saying there shouldn't be any ambiguity about 12AM or 12PM in the first place.

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.

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

#60

Post by icedchai »

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.

Actually, it does make more sense to group them. You see that 12 at the beginning of 12:00 and 12:01?

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!"

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