Why Are There 60 Minutes In An Hour Instead of 100?

Do clocks really follow a system inherited from ancient Sumeria?

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,
it's Christian Seger in. Today's question is why do we
measure time the way we do? At the first glance,
it seems like it's a sensible thing until we start
delving into it. So let's start with a day. What
is a day? A day is just the amount of

(00:22):
time that it takes our globe to make a full
rotation on its axis. Simple, right, But then we divide
a day into twenty four parts for some reason, and
then of those twenty four hours we measure those in
sixty minute increments for some reason. And then we get
down to a minute, we measure that in terms of seconds,

(00:44):
again a collection of sixty for some reason. But when
we get to seconds, we measure those in the most
popular numerical system today, the decimal system, So we talk
in terms of a hundredth of a second or a
millionth of a second. But why how do we even
start measuring days and dividing them this way? Well, the

(01:05):
Babylonians were measuring time in what's called a sexy gesimal
system as opposed to a decimal system. They were based
on sixty instead of base ten, So earlier we said
that the decimal system is the most popular, and it
makes sense right because the vast majority of human beings
have ten fingers. It's very easy for the human species

(01:27):
to count to ten. So why would you use something
that relies on sixty or why would you use something
that relies on twelve. Well, when we look at the
Babylonian system, it actually makes some sense. There is some
method to this ancient madness. And here's why. If we
use the base ten idea ten to one hundred, the

(01:48):
notation that we would have to make to measure a
specific time of day would become ridiculous very quickly, and
complicated as well. The thing is that sixty has some
advantages because sixty, if you just break it down, is
essentially five times twelve. Then it has both the advantages
of a ten and twelve as a system. So that

(02:11):
is why it makes sense for us to use sixty
seconds in sixty minutes. But the big explanation that no
one's figured out yet is how this spread around the world.
Did it happen because it was an accident of history?
Did it happen because it was really the most efficient
way that human beings have figured out how to measure time.
And one last thing. We're all familiar with AM and PM, right.

(02:34):
AM stands for anti meridium and PM stands for post meridium.
These are terms that came about during the Roman era
when they used to divide the entire day into two things,
just AM and PM. This was so important, in fact,
that they used to have these people whose only job
was to wait until the sun crossed over so they

(02:57):
could run to the forum and say, every buddy, okay,
it is noon. It is officially p M. And the
reason why is because lawyers were required to show up
by noon. Check out the Brainstuff channel on YouTube, and
for more on this and thousands of other topics, visit

(03:19):
how stuff works dot com.