作者：HOLLY LARGE
Compilation: Muggle
图片来源：Sinseeho/Shutterstock.com
It's time to revisit that old Latin textbook. Do you prefer a 12-hour or 24-hour clock? Most of us know at a very young age that "am" and "pm" refer to the first and second half of the day, or the morning and afternoon/evening – but what do these letters actually represent?
Pay attention to Latin
Some may think that Latin is a language that has been lost, but look around, its influence is everywhere, including how we describe time. "AM" stands for the Latin phrase Ante Meridiem, which translates into English to mean "before noon". On the other hand (of course, if you are looking at a 12-hour clock, the same hands) , "pm" stands for meridian, which means "afternoon".
If you want to say something pedantic the next time you hear someone say 12 a.m. or 12 p.m., it means you can tell them that it's not strictly right to do so – you can't do it past noon at 12 noon, because it's noon. The Royal Museum of Greenwich recommends sticking to 12 noon or 12 midnight.
That being said, if you point this out at every opportunity, people might find you a bit annoying.
Punctuation or no punctuation
According to the Chicago Handbook, there are a total of six ways to write abbreviations: all caps with a period, all caps without a period, lowercase letters with a period, lowercase letters without a period, lowercase without a period, and lowercase without a period.
For a long time, many formal style guides, including Chicago, tended to use capital letters with periods. While this may still be present in some academic settings or publishing houses, for example, any way you want to write now is generally considered acceptable – just consistent with what you're using.
Less confusing way
If you're worried about accidentally showing up at the airport at 4 p.m., when your flight is actually 4 a.m. (objectively speaking, it's worth missing a flight), then you might want to switch to the 24-hour clock.
While your friends may berate you for pretending to be in the military, this can be a less confusing approach. For example, midnight is no longer 12 a.m., but 00:00, which makes a lot of sense considering that it is the beginning of the day.
Where the part becomes slightly unfamiliar is after 1 p.m., not 13:00, and so on until midnight, which actually still has its problems - should it be 00:00 or 24:00? I'll leave that to your discussion.
Source: https://www.iflscience.com/what-do-am-and-pm-actually-mean-73804
作者：HOLLY LARGE
HOLLY IS A MEDICAL BIOCHEMISTRY GRADUATE STUDENT WHO IS PASSIONATE ABOUT MAKING SCIENCE FUN, INTERESTING, AND EASY TO UNDERSTAND.