AM is ante meridian - PM post meridian. Meridian is midday.

▲ godelski 5 days ago | parent | next [-]

Another way to remember is that A is before P alphabetically. Probably easier to remember if you don't need the other concepts

▲ 01HNNWZ0MV43FF 5 days ago | parent | prev [-]

But midnight is exactly 12 hours post and ante meridian. And meridian is neither 12 hours post nor ante of itself.

Where I can, I just say "noon" and "midnight". 12-hour time is frustrating because of this 0 == 12 bullshit

▲ exidy 5 days ago | parent | next [-]

This is the problem with the digital world. Time is analogue and continuous, digital clocks are just a quantised approximation.

Midday and midnight are points in time that have no duration -- as soon as they are observed they are passed, so midnight is 12am and midday is 12pm.

This is easier to visualise on an analogue clock with a continuous seconds hand. Although the hand sweeps past 12 it spends no time there.

Alternatively think of a digital clock with very high precision. While your ordinary clock will show 12:00pm at midday for a full minute, your high precision clock might be showing 12:00:00.0000001 -- indisputably "post meridiem".

▲ bubblebobble99 5 days ago | parent | prev [-]

That’s the point though. They are called noon/midday and midnight. There is no am/pm on the 12. It’s 11:59pm, midnight, 12:01am, and 11:59am, midday, 12:01pm. Really it’s not that confusing, it’s just two points in time in the whole day and it’s fairly easily to tell which of them you are at unless you are close to the poles.we’ve managed to cope this long with them.

	▲	exidy 5 days ago \| parent \| next [-]
		This isn't right. Midday / midnight are not the 60 seconds it takes for a digital clock to go from showing 12:00 to 12:01. They are the infinitesimally small point in time that mark the transition between "before" and "after". Like throwing a ball up into air, there is no time where it is not either rising or falling, but there is a point where it transitions from one to the other. So midday is 12:00pm. As soon as the moment has been observed it has passed, and you are now "post meridiem".
	▲	dimava 5 days ago \| parent \| prev \| next [-]
		Except 12:01 is in 24-hour clock which doesn't have 12:00 problem in the first place
	▲	godelski 5 days ago \| parent \| prev \| next [-]
		`> There is no am/pm on the 12.` This is 100% false. What are you even talking about? It's so obviously false too `> it’s fairly easily to tell which of them you are at unless you are close to the poles` How does looking out the window help set an alarm? `> we’ve managed to cope this long with them.` Look, I'm American too and I get AM/PM but lots of the world uses 24hr clocks. Maybe if you stop talking about how smart you are you'll actually be able to hear the question you're trying to answer. It'll go a long way to making other people think you're smart.
	▲	zoover2020 5 days ago \| parent \| prev [-]
		That's a lot of mental gymnastics to say 24h clock is easier