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Is It Really 12 AM Or 12 PM?
(And Which Of Those Two Times Is Actually Noon?)
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( Note: I'm not asking you to merely "parrot back" what somebody else thinks the answers are.
Instead, I'm going to show you how you can easily figure out the correct answers yourself. )
Before I show you how to arrive at the correct answer to the question "Is midnight 12 AM or 12 PM?", let me just tell you that the correct answer is not "Midnight is neither one". Midnight very definitely is one of the two given choices. And that choice (either "AM" or "PM") pertains to the entire midnight hour, not just to the instant of midnight. (For example, it doesn't change at 12:01.)
First, let's consider what the letters "AM" and "PM" mean: They stand for the two Latin terms: "Ante Meridiam" and "Post Meridiam" respectively. In the case of the "PM" hours, the number that you put in front of the letters "PM" indicates (in principle) the number of hours that have elapsed since the previous crossing of the meridian by the sun.*
*(The time of the actual meridian crossing depends on such things as your specific longitude, whether or not you are
currently observing Daylight Savings Time, etc. But, for our present discussion, we need not be quite so literal.
We can just loosely refer to the term "meridian crossing" as meaning "around Noon time".)
Therefore, 1 PM means that one hour of time has elapsed since the previous meridian crossing (i.e., since noon), 2 PM means that two hours have elapsed, etc. When we finally reach eleven hours since the previous meridian crossing, we call it 11 PM. (I.e., eleven hours "post meridiam").
Is that clear to you? If not, then let me repeat: 11 PM means that eleven hours of time have elapsed since the previous meridian crossing (i.e., since noon).
Now, let me ask you a "real toughie" question: If we wait one more hour (past 11 PM), how many hours will have elapsed since the previous meridian crossing? In other words, how many hours will have elapsed since noon?
Well (duh!), the answer is (of course): twelve hours will have elapsed since the previous meridian crossing. (I.e., twelve hours "post meridiam", or 12 PM).
So, there you have it! Midnight is 12 PM!
Now, 12 PM cannot refer to both midnight and noon. And we've just shown that 12 PM refers to midnight.
Therefore, Noon is 12 AM (as can be easily verified independently by using similar arguments).
(See how easy it was to figure out the correct answers to the questions about Noon and Midnight? All you had to do was merely ignore everyone else's misconceptions and just apply a little common sense! )
Still not entirely convinced? Then let's continue with the discussion . . .
Remember: Once you begin counting the "PM" hours (1 PM, 2 PM, 3 PM, etc.), you must continue counting those "PM" hours (10 PM, 11 PM, 12 PM), until you reach the "AM" hours. Then, when you finally do reach the "AM" hours, you begin counting all over again, starting with the number "one" (i.e., 1 AM, 2 AM, 3 AM, etc.). [As you should know by now, whenever you count anything (be they hours, fingers, or chickens), you never start counting them by beginning with the number "twelve"! Therefore, the very first "AM" hour of the day is not twelve AM. The very first "AM" hour of the day is one AM.]
"But," you might argue, "Midnight can also be thought of as being twelve hours before the next meridian crossing. Therefore, shouldn't it be equally valid for midnight to be called 12 AM?" (I.e., twelve hours "ante meridiem")
No! Because the number in front of the "AM" letters indicates the number of hours (of the new day) that have already elapsed prior to the next meridian crossing. Since the new day starts at midnight, that number in front of the "AM" letters therefore represents the number of hours that have elapsed since midnight. (For example, 1 AM means that one hour has elapsed since midnight, 2 AM means that two hours have elapsed since midnight, etc.) Therefore, attempting to refer to midnight as being "12 AM" would be tantamount to making the clearly absurd claim that midnight occurs twelve hours after midnight!
But, to further clarify these ideas, let's not stop at midnight. Let's keep on counting (or more correctly, "measuring") the number of hours and minutes past midnight:
12:00 PM, 12:01 PM, 12:02 PM, 12:03 PM, . . . 12:58 PM, 12:59PM, . . .
Now (in one more minute after 12:59 PM), how many hours will have elapsed since the previous meridian crossing?
Answer: 13 hours will have elapsed since the previous meridian crossing. (13 hours "post meridiam".) Therefore one hour past midnight must be 13 PM, two hours past midnight must be 14 PM,... and so on.
Notice that you do not have to switch from units of PM hours to units of AM hours, just because you've gone past the midnight hour. It's perfectly legitimate to keep counting the PM hours for as long as you like. And similarly for the AM hours: You do not have to switch from units of AM hours to units of PM hours, just because you've gone past noon.*
*And the same kind of discussion holds true for measuring other things as well. For example, there's no physical temperature at which you must switch from units of Fahrenheit degrees to units of Centigrade degrees. Any temperature can be expressed in terms of either of those units. Similarily, when measuring the length of a long piece of string with a ruler, you do not have to switch from units of "inches" to units of "feet" just because you've gone past the ruler's 12-inch mark.
Therefore, any time of the day or night can be legitimately expressed as either an AM time or a PM time, depending on the numbers that you put in front of those 2-letter abbreviations. (You can think of the letters "AM" and "PM" as merely designating abstract reference points for measuring time. They do not necessarily indicate literally the current location of the sun with respect to your meridian -- which, as we have already mentioned, depends upon such things as your local longitude, time of year, etc.)
Yes, I know. Using a number greater than 12 to refer to a time (such as 13 PM, 14 PM, etc.) may seem a little unnatural at first. But it's really not much different than allowing the idea of "improper fractions" in arithmetic (i.e., fractions whose values are greater than 1.0) ... such as 5/3. (After all, how can a "fraction" of something be greater than the whole thing? )
Borrowing the word "improper" from the term "improper fractions" (which refers to fractions that are, in a sense, "too big"), perhaps we should refer to times whose numerical portions are greater than 12 (such as: 13 PM, 14 PM, etc.) as being "improper times". However, such times are perfectly valid times, even though those times could be expressed more "properly" as: 1 AM (of the following day), 2 AM (of the following day), etc.
And, of course, one hour past noon could be legitimately expressed as being either 13 AM or 1 PM, two hours past noon could be expressed as being either 14 AM or 2 PM, etc.
As a last resort in trying to avoid accepting the actual truth about midnight and noon, someone might be tempted to suggest: "Well, let's just define midnight as being 12 AM and noon as being 12 PM, since that's what everybody says they are."
The problem with this suggestion is that truth is not determined by popular opinion.* And you cannot change a truth by merely "redefining" it to be something that it isn't.
*For example, there was a time when everyone thought that the earth was located at the center of the universe, and that everything (the sun and the moon and all the stars) went around the earth. (It was referred to as the "Ptolemaic Theory".) But just because everybody had the opinion that the earth was at the center of the universe, it didn't make it actually true in reality.
The measurement and specification of time is akin to a mathematical process. And you cannot redefine the laws of mathematics (and thereby introduce needless inconsistencies) for the sole purpose of perpetuating former mistakes in reasoning. (For example, just imagine the number of mathematical inconsistencies that would arise if we were to "define" the value "one" to be identically equal to the value "two". )
(For further discussion about truth and consistency, see Chapter Zero of my book, "Shades of Reality".)
Many naive individuals who don't really understand what the numbers on a clock mean (and who don't know how to correctly associate those numbers with the abbreviations "AM" and "PM"), simplistically think that any time which is later than 12 o'clock midnight must be an "AM" time, and that any time which is later 12 o'clock noon must be a "PM" time. (For example, they incorrectly refer to one minute past noon as being "12:01 PM".)
This kind of thinking is, of course, clearly erroneous because it fails to recognize the fact that the numbers on a clock (particularly the number "12") each have well-defined mathematical associations with their corresponding "AM" and "PM" letters. The numbers on a clock are not merely arbitrary and meaningless labels onto which you are free to independently append your choice of either an "AM" or a "PM". Instead, a number and its "AM/PM" letters comprise a single entity, and so those two components must remain intact. [For example, just because the current time may happen to be one minute past noon, you cannot just grab the "12:01" part of "12:01 AM" and then (because it's past noon), throw away the "AM" part and merely stick the letters "PM" onto the numbers instead.]
But still, you're probably thinking: "Even if it's only one minute past noon, then somehow it's just got to be a PM time. After all, PM refers to afternoon time, right? So why can't we use a "PM" for legitimately designating the noon hour times? (And similarly, why can't we use an "AM" for designating the midnight times?)"
The answer is: We can!
As we've already intimated, one way of expressing noon as a PM time would be to call it 24 PM. But then, having to refer to noon as "24 PM" is a little awkward because "24 PM" isn't a "proper" time. (Its numerical portion is greater than 12.) And, as we know, we can't refer to noon as being 12 PM, because that would be tantamount to making the clearly absurd claim that noon occurs 12 hours past noon! However, referring to noon as being zero PM does make perfectly good sense... since noon does occur zero hours past noon. (And similarly, referring to midnight as being zero AM also makes perfectly good sense... since midnight does occur zero hours past midnight.)
Therefore, we can refer to noon as: zero o'clock PM, and we can refer to midnight as: zero o'clock AM.
If we use the concept of "zero o'clock" instead of "twelve o'clock", then we can make completely valid the simple notion that "any time which is later than noon must be a 'PM' time, and that any time which is later midnight must be an 'AM' time". (This idea of using "zero o'clock" to express noon and midnight makes a whole lot more sense than the way we currently do it.)
[What? You say that your clock doesn't have a zero on it? Well, that's easy enough to fix. Just scrape off the twelve (which never should have been put there in the first place) and paste on a zero instead! ]
Midnight is twelve PM (or equivalently, zero AM), and that designation of "PM" (or "AM") remains in effect for the entire midnight hour (i.e., until one AM).
Noon is twelve AM (or equivalently, zero PM), and that designation of "AM" (or "PM") remains in effect for the entire noon hour (i.e., until one PM).
At this point, the story about "The Emperor's New Clothes" comes to mind. It's about two weavers who promise an emperor a new suit of clothes that is invisible to anybody who is stupid, or incompetent. When the emperor decides to parade in front his subjects, the townsfolk play along with the pretense of seeing his clothes because they don't want to appear stupid. However a little boy recognizes the truth and cries out, "But he isn't wearing anything at all!"
Now that you know the truth about 12 AM and 12 PM, what are you going to do? Are you going to openly admit that noon is actually 12 AM and that midnight is actually 12 PM? Or are you going to keep on pretending just the opposite so that you can continue to conform with all of the fools who pretend not to know any better?