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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?

#21

Post by FabHK »

mywittyname wrote: post #17
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…

Well, since 9.9999999... = 10 [0], then 50 + 9.999999... = 50 + 10 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

Well, while the numbers of nines is finite, it's still AM.

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.

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

#22

Post by marsrover »

mc32 wrote: post #19
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.

But special sales at stores and online do begin at midnight. Say new playstation, iPhone, Xbox, etc.

Well, it's not ambiguous what the word "midnight" means.

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

#23

Post by function_seven »

coldtea wrote: post #15
Finnucane wrote: post #7

Earlier quoted context omitted.

But whose 24 hour clock? Should we all be on GMT? That's arbitrary and eurocentric. And let's get rid of those pesky arbitrary time zones too. We should all be able to have our own personal time zones.

> 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?")

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

#24

Post by jjoonathan »

mywittyname wrote: post #17
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…

Well, since 9.9999999... = 10 [0], then 50 + 9.999999... = 50 + 10 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

Limits work from both directions. 12:00:00.1 is PM, 12:00:00.00001 is PM, so 12:00:00 is PM. Contradiction. /s, it's all in good fun :)

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

#26

Post by Symbiote »

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.

I think trains in Britain avoid being scheduled to leave at 00:00, it's easy enough to leave at 23:59 at that time. It's not busy. But 12:00 wouldn't be ambiguous, since that can't be 00:00 or 24:00.

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.")

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

#27

Post by FabHK »

naikrovek wrote: post #11
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…

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!

> I read it somewhere but I can't remember where.

Maybe in the stackoverflow answer we're discussing here? :-)

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

#28

Post by FabHK »

marsrover wrote: post #22
mc32 wrote: post #19

Earlier quoted context omitted.

But special sales at stores and online do begin at midnight. Say new playstation, iPhone, Xbox, etc.

Well, it's not ambiguous what the word "midnight" means.

It is, when it's attached to a day - it could be at the very beginning of that day or the very end.

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

#30

Post by frandroid »

When the bells of Big Ben — or any chiming clock that rings out the hours of the day — chimes with one bell, we know that the first hour has just been completed. As one commenter observes, having it ring zero bells wouldn’t tell people what time it is. You can’t go from ringing eleven bells one hour to not ringing any bells at all an hour later to then ringing one bell the hour following the one in which you failed to ring any bells at all. People wouldn’t be able to tell what time it was because of something they didn’t hear!

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!
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