How it Works4 mins ago
What's the time?
I'm not sure if this is the right category, or if it should be in Phrases & Sayings - or even Quizzes and puzzles - but...
We've been having a discussion about noon and midnight and can't agree. It goes something like this.
Given that ante-meridien (a.m.) means "before noon" and post-meridien (p.m.) means "after noon", which should be used to describe noon itself.
i.e. is 12a.m. midnight or noon. Similarly for 12p.m.
Anyone know if this is defined anywhere?
Cheers
Duncan
We've been having a discussion about noon and midnight and can't agree. It goes something like this.
Given that ante-meridien (a.m.) means "before noon" and post-meridien (p.m.) means "after noon", which should be used to describe noon itself.
i.e. is 12a.m. midnight or noon. Similarly for 12p.m.
Anyone know if this is defined anywhere?
Cheers
Duncan
Answers
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That's what I suggested but for various reasons it's not possible in this context. E.g. you walk into a room with a digital clock (set to a 12 hour time display) showing 12:00 a.m. What time is it (assuming the clock is accurate)?
The Greenwich Mean Time website suggests that both terms are meaningless but it also says that the new day starts at midnight (0:00:00). It seems to me that we may have a case for using 12:00a.m. to mean midnight as it is the earliest possibly time of day before noon. 12:00p.m. is still problematical however but could be considered as noon simply because it can't be midnight.
I'm still unconvinced, but there must be a convention that the manufacturers of digital clocks use.
Incidentally, it is possible to have a time of 11:59:60 p.m., which I find amusing. It happens when they add a leap second.
Cheers
Duncan
The Greenwich Mean Time website suggests that both terms are meaningless but it also says that the new day starts at midnight (0:00:00). It seems to me that we may have a case for using 12:00a.m. to mean midnight as it is the earliest possibly time of day before noon. 12:00p.m. is still problematical however but could be considered as noon simply because it can't be midnight.
I'm still unconvinced, but there must be a convention that the manufacturers of digital clocks use.
Incidentally, it is possible to have a time of 11:59:60 p.m., which I find amusing. It happens when they add a leap second.
Cheers
Duncan
If you stuck to the literal meanings then 12am would be midnight (12 hours before the middle of the day) and 12pm would also be midnight (12 hours after the middle of the day).
So 12am and 12pm both denote midnight.
Which is why no sensible person uses either, and talks only of "12 noon" and "12 midnight".
So 12am and 12pm both denote midnight.
Which is why no sensible person uses either, and talks only of "12 noon" and "12 midnight".
Hi Duncan, I've been wondering about that one, too. Seems it really is problematic
AM and PM refer to which side of the meridian the Sun is currently positioned. Midnight and Midday are neither AM or PM. The �Sun� is crossing (or opposite to) and is neither before nor after the meridian at that instant.
Conversely the Sun is not a point in space nor can the exact centre of the Sun be distinguished. The Sun�s centre can only be defined by an agreed approximation, no matter how precisely one attempts to discern it. In fact, because of its angular size, the Sun lies on both sides of the meridian at noon . . . for about two minutes each day . . . (depending on its current position between apogee and perigee and its defined boundaries, solar flares and the like).
Unless and until a specific definition of the instant the Sun crosses the meridian is agreed upon by convention, 12:00:00.0 AM or PM remain meaningless (undefined) instants in time by virtue of the aforementioned vagaries . . . period.
Unless and until all concerned parties can agree that the Sun is approaching or has crossed the meridian AM and/or PM remain undefined. In this light I would submit that it would be reasonable to suggest that any time within the twelve hours preceding 12:00:00.0 midday is AM and likewise any time following 12:00:00.0 midday is PM. If you can not and/or do not agree with this convention than perhaps we should just drop the whole thing.
Have a nice day! ;o)
Conversely the Sun is not a point in space nor can the exact centre of the Sun be distinguished. The Sun�s centre can only be defined by an agreed approximation, no matter how precisely one attempts to discern it. In fact, because of its angular size, the Sun lies on both sides of the meridian at noon . . . for about two minutes each day . . . (depending on its current position between apogee and perigee and its defined boundaries, solar flares and the like).
Unless and until a specific definition of the instant the Sun crosses the meridian is agreed upon by convention, 12:00:00.0 AM or PM remain meaningless (undefined) instants in time by virtue of the aforementioned vagaries . . . period.
Unless and until all concerned parties can agree that the Sun is approaching or has crossed the meridian AM and/or PM remain undefined. In this light I would submit that it would be reasonable to suggest that any time within the twelve hours preceding 12:00:00.0 midday is AM and likewise any time following 12:00:00.0 midday is PM. If you can not and/or do not agree with this convention than perhaps we should just drop the whole thing.
Have a nice day! ;o)
That�s all fine and dandy, mibn2cweus, and an excellent explanation of the term �meridian�.
However, divlong is referring to the annotation used to denote the time of day. Although that annotation uses the term �meridian� I cannot accept that, because the term is not defined rigidly enough for scientists, that it cannot be used in time annotation.
The terms �am� and �pm� are used to denote what side of noon (as shown by a 12 hour clock) the stated time refers to. Although its origin may stem from the positioning of the sun, in this context the position of the sun is not material. If it were, then noon would be at a different instant across each time zone, and convention dictates that it is not.
In my (non-scientific) view, am and pm refer to the times shown by a clock. Noon and Midnight are the reference points of that system. Noon is the mid point of the 24 hour day, and noon and midnight are neither am nor pm.
Let�s not allow science to cloud a fairly straightforward issue!
However, divlong is referring to the annotation used to denote the time of day. Although that annotation uses the term �meridian� I cannot accept that, because the term is not defined rigidly enough for scientists, that it cannot be used in time annotation.
The terms �am� and �pm� are used to denote what side of noon (as shown by a 12 hour clock) the stated time refers to. Although its origin may stem from the positioning of the sun, in this context the position of the sun is not material. If it were, then noon would be at a different instant across each time zone, and convention dictates that it is not.
In my (non-scientific) view, am and pm refer to the times shown by a clock. Noon and Midnight are the reference points of that system. Noon is the mid point of the 24 hour day, and noon and midnight are neither am nor pm.
Let�s not allow science to cloud a fairly straightforward issue!
New Judge, I agree that the terms should be allowed to evolve to apply to our current and improved methods of keeping time. The point of my previous post was to show previous steps in that evolution so that we might come to a mutually beneficial agreement on how those terms should be used in the future (until someone proposes a better definition).
Most importantly I am of the opinion that we do agree completely on what should be the standing definition and can therefore use it to communicate without ambiguity, an ideal your additional clarification (and hopefully mine) has further promoted in my estimation.
Most importantly I am of the opinion that we do agree completely on what should be the standing definition and can therefore use it to communicate without ambiguity, an ideal your additional clarification (and hopefully mine) has further promoted in my estimation.
The convention with clocks (including MS Windows) is that 12.00PM is noon and 12.00AM is midnight.
This is probably because most digital clocks do not show the seconds and even though for a nanosecond at 12 noon for instance it really is neither AM nor PM for the rest of that entire minute it is 12.00 and however many nanoseconds/seconds etc. therefore being 12.00PM shown on the clock.
This is probably because most digital clocks do not show the seconds and even though for a nanosecond at 12 noon for instance it really is neither AM nor PM for the rest of that entire minute it is 12.00 and however many nanoseconds/seconds etc. therefore being 12.00PM shown on the clock.
Thanks, guys & gals, for all your answers - especially Swedeheart for the Wikipedia link (can't think why that one didn't come up on my search) and Chakka35 who is apparently using the Roman method of indicating the time :-).
Anyway, I think some people are missing the point slightly. The use of a.m. and p.m. in this case can only be a convention so the precise definition of meridian is somewhat moot. Indeed, I believe I implied this in my second post. The idea that midnight cannot be a.m. or p.m. is clearly wrong as it is not itself a meridian time - only noon is. As the day starts at midnight then it is clearly before noon chronologically and must therefore be a.m. - which leaves p.m. to be used for noon.
It seems that most people who use it agree that 12 a.m. is midnight and 12 p.m. is noon - with the exception of the US Government Printing Office who seem to feel that it should be the other way round, but that's Government departments for you.
So thanks again everyone for your comments.
Anyway, I think some people are missing the point slightly. The use of a.m. and p.m. in this case can only be a convention so the precise definition of meridian is somewhat moot. Indeed, I believe I implied this in my second post. The idea that midnight cannot be a.m. or p.m. is clearly wrong as it is not itself a meridian time - only noon is. As the day starts at midnight then it is clearly before noon chronologically and must therefore be a.m. - which leaves p.m. to be used for noon.
It seems that most people who use it agree that 12 a.m. is midnight and 12 p.m. is noon - with the exception of the US Government Printing Office who seem to feel that it should be the other way round, but that's Government departments for you.
So thanks again everyone for your comments.
I can't imagine why people are making such a fuss over something so simple. As I explained above, 12am and 12pm can both refer only to midnight, therefore it is daft ever to use either. 'Noon' and 'midnght' is all you need, with or without a preceding '12'.
If, as you suggest, most people consider 12am to be midnight, they are right. If they also consider 12pm to be noon they are wrong. Can't they count?
And I am mystified by your reference to my 'using the Roman method'. Sounds like a form of contraception. Explain.please.
If, as you suggest, most people consider 12am to be midnight, they are right. If they also consider 12pm to be noon they are wrong. Can't they count?
And I am mystified by your reference to my 'using the Roman method'. Sounds like a form of contraception. Explain.please.
Hi Chakka,
In your first post you seemed to be saying that 12 a.m. means 12 hours before noon. That suggests that 1 a.m. is one hour before noon (i.e. 11:00 hours). This is how the Romans originally used this nomenclature, according to the Wikipedia article that SwedeHeart posted a link to.
No offence meant.
Incidentally, as the new day starts at midnight, 12 hours after noon is actually the next day (i.e. the morning of the next day) so it is still 12 a.m.
I'm not saying that using this nomenclature is sensible, just asking what the convention is - and that seems to have been answered now.
In your first post you seemed to be saying that 12 a.m. means 12 hours before noon. That suggests that 1 a.m. is one hour before noon (i.e. 11:00 hours). This is how the Romans originally used this nomenclature, according to the Wikipedia article that SwedeHeart posted a link to.
No offence meant.
Incidentally, as the new day starts at midnight, 12 hours after noon is actually the next day (i.e. the morning of the next day) so it is still 12 a.m.
I'm not saying that using this nomenclature is sensible, just asking what the convention is - and that seems to have been answered now.
Toureman is right in that the military do not use 24:00, nor do they use 00:00 - it's always 23:59 or 00:01. Their reason for this is so as to place an event as happening on a particular date.
It's said that there has been one exception to this convention. Apparently Eisenhower, as Commander-in -Chief of Allied Forces in Europe, insisted that the launch of D-Day would commence at 00:00 on 6th June, rather than at 00:01
It's said that there has been one exception to this convention. Apparently Eisenhower, as Commander-in -Chief of Allied Forces in Europe, insisted that the launch of D-Day would commence at 00:00 on 6th June, rather than at 00:01
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