> I've met grown adults that think 12 PM is the middle of the night already. (They don't understand PM vs AM.)
That's because it doesn't make any sense to describe the middle of the day by '12 PM', since 'PM' should mean "after midday". To be sure we have conventions about this, but not knowing those arbitrary conventions is no reason to think that people don't understand the concept. I think better usage is 12 noon and 12 midnight (https://en.wikipedia.org/wiki/12-hour_clock#Confusion_at_noo... )—though that still requires further disambiguation at midnight (is "midnight on August 3" between August 2 and 3, or between August 3 and 4? I don't know whether there's a common disambiguation here, as with 12 n versus 12 m).
The inconsistency is in using 12 instead of zero, which results in four discontinuities per day (12:59 AM → 1:00 AM, 11:59 AM → 12:00 PM, 12:59 PM → 1:00 PM, 11:59 PM → 12:00 AM). The times should be divided into 0:00 AM through 11:59 AM and 0:00 PM through 11:59 PM so that the hours wrap around at the AM/PM boundary, not one hour later.
> The times should be divided into 0:00 AM through 11:59 AM and 0:00 PM through 11:59 PM so that the hours wrap around at the AM/PM boundary, not one hour later.
Sure, although, if we're re-defining how people tell time anyway, we might as well use a 24-hour clock and so avoid the need for AM/PM at all; and, even if we do that, there is still, inevitably, the confusion about on what day 00:00 AM falls. My point was just that not knowing that "12 PM" means noon is a matter of not being aware of an arbitrary convention, rather than of not understanding the concept of AM vs. PM. (Indeed, arguably it is a matter of understanding their meaning all too well!)
I just checked my OS X machine, it has it.
My Linux machine has it, though I grant that among the many DEs for Linux, some might not use it. (I use MATE, a fork of GNOME 2, for reference.)
And I've Googled a screenshot of Windows, which seems to still use it.
My phone, microwave, and stove, I guess, seem to presume I know whether it is morning or not.
If you use US/UK localisation, yes. I don't use language localizations (since translation is often poor/missing so you get a mix, and I have to learn new terminology all the time) but you bet I want my 24-hour clock and not that old Latin stuff.
Perhaps in your country. Iny the vast majority of countries I've been to, opening hours on shops, timetable, TV schedules, phones, etc are 24 hours. Have been for decades.
> The average person doesn't use 24 hour/military time. Maybe in the tech world.
True in the US (and IIRC the Anglophone world more generally), but AFAIK 24-hour is more commonly used outside of military/technical domains in many other countries.
> That's because it doesn't make any sense to describe the middle of the day by '12 PM', since 'PM' should mean "after midday".
I think that explanation fails because, IME, people who know that “PM” means “post meridiem” which means “after midday” are more, not less, likely to also know that 12:00 PM is noon than those to whom PM is just an arbitrary marker.
> 12 PM = noon is something I remember learning in kindergarden, and should be common knowledge for most adults in the US.
Well, maybe, although assuming a commonality between others' education and mine is always dangerous; but I've got way more respect for someone who understands a concept but doesn't know about an arbitrary exception to it, than for someone who understands a pile of arbitrary rules and doesn't know how to fit them to any conceptual framework.
That's because it doesn't make any sense to describe the middle of the day by '12 PM', since 'PM' should mean "after midday". To be sure we have conventions about this, but not knowing those arbitrary conventions is no reason to think that people don't understand the concept. I think better usage is 12 noon and 12 midnight (https://en.wikipedia.org/wiki/12-hour_clock#Confusion_at_noo... )—though that still requires further disambiguation at midnight (is "midnight on August 3" between August 2 and 3, or between August 3 and 4? I don't know whether there's a common disambiguation here, as with 12 n versus 12 m).