Time is a weird thing. We feel it slipping away while we’re stuck in traffic, yet we can’t actually touch it. To make sense of this invisible flow, humans invented units of a period—specific chunks of time that help us organize everything from a quick nap to a century-long legacy. Most of us just glance at a watch and see numbers, but there is a massive, complex history behind why a minute has sixty seconds and why a month doesn't always have thirty days. It's actually kind of a mess if you look closely.
Ever wonder why we don’t use a decimal system for time? We use base-10 for money and distance. It would be so much easier if there were 100 minutes in an hour. But we don’t. We’re stuck with the leftovers of ancient Sumerian and Babylonian math. They loved the number 60 because it's divisible by almost everything.
The Sumerian Legacy and the 60-Second Stress
The way we define the smallest common units of a period—the second and the minute—is basically a 5,000-year-old hand-me-down. The Sumerians used a sexagesimal (base-60) system. Why? Because 60 is incredibly functional. You can divide it by 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30. If you’re a merchant in an ancient market trying to divide a "period" of labor or a shipment of grain, 60 is your best friend.
Then the Greeks came along. Eratosthenes and Hipparchus used these Babylonian concepts to map out the earth and the sky. Eventually, we got the partes minutae primae (the first small parts, or minutes) and the partes minutae secundae (the second small parts, or seconds).
It's strange. We live in a digital world, but our heartbeat and our deadlines are governed by the math of people who lived in mud-brick cities. Honestly, if we tried to change it now, the entire global economy would probably collapse. Imagine trying to reprogram every server on earth to recognize a "metric hour." It’s not happening.
When Nature Dictates the Calendar
The bigger units of a period, like days and years, aren't arbitrary. Physics forces these on us. A day is one rotation of the Earth. A year is one trip around the Sun. Pretty straightforward, right?
📖 Related: Finding the Right Words: Quotes About Sons That Actually Mean Something
Not really.
Nature doesn't care about clean numbers. The Earth takes about $365.24219$ days to orbit the sun. That ".24219" is the reason your calendar is a liar. If we didn't have leap years, the seasons would slowly drift. In a few hundred years, July in the Northern Hemisphere would be freezing cold.
The Month: A Failed Relationship with the Moon
The "month" is perhaps the most frustrating of all units of a period. It’s supposed to be based on the lunar cycle, which is roughly 29.5 days. But because 29.5 doesn't go into 365 evenly, we ended up with this weird, jagged system of 28, 30, and 31-day months. Julius Caesar and later Pope Gregory XIII had to basically "fix" time because the holidays were drifting.
The Gregorian calendar, which most of the world uses today, was introduced in 1582. It was so controversial at the time that some countries refused to adopt it for centuries. Britain didn't switch until 1752. When they finally did, people actually rioted in the streets because they felt the government had "stolen" 11 days of their lives.
The Week is Purely Human
Unlike the day or the year, the week has no basis in nature. There is no celestial body that orbits anything in seven days. It is a purely social construct.
👉 See also: Williams Sonoma Deer Park IL: What Most People Get Wrong About This Kitchen Icon
Most historians point to the Babylonians again, who observed seven "wandering stars" (the Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn) and dedicated a day to each. This seven-day rhythm became so deeply embedded in human culture—largely through religious tradition—that it is now the most rigid of all units of a period. We’ve tried to change it. The French Revolutionaries tried a 10-day week (the "décade") to be more "rational." The Soviet Union tried 5-day and 6-day weeks to keep factories running 24/7.
Both failed miserably. People hated it. Turns out, we’re psychologically hooked on that seventh day of rest.
How We Measure High-Precision Periods Now
In the past, we measured time by the sun. Then by swinging pendulums. Today, we use the atom.
The official definition of a second isn't "1/60th of a minute" anymore. Since 1967, it has been defined by the International System of Units (SI) as the duration of $9,192,631,770$ periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.
That is incredibly precise.
✨ Don't miss: Finding the most affordable way to live when everything feels too expensive
We need that precision for GPS. If the units of a period used by satellites were off by even a billionth of a second, the location on your phone would be off by kilometers. We are literally tethered to the vibrations of an atom just to find the nearest Starbucks.
Misconceptions About Time Units
People often think time is a constant. It’s not.
According to Einstein's theory of relativity, time is flexible. If you spend a year on a spaceship traveling near the speed of light, you might return to Earth to find that ten years have passed for everyone else. Your "unit of a period" was different than theirs.
Even on Earth, time isn't perfectly uniform. The Earth’s rotation is actually slowing down very slightly due to tidal friction from the moon. Every now and then, the International Earth Rotation and Reference Systems Service (IERS) has to add a "leap second" to our clocks to keep them in sync with the planet's actual rotation.
Making Time Work for You
Understanding these units is more than just a history lesson. It’s about how you manage your life. Most people struggle with "time blindness," the inability to accurately sense how long a "period" actually is.
- The 15-Minute Rule: Break your tasks into 15-minute blocks. It's a small enough unit to be manageable but large enough to get something done.
- Audit Your Cycles: We often think in days, but our bodies work in 90-minute ultradian rhythms. Try working for 90 minutes and then taking a 15-minute break.
- Respect the Buffer: Since nature doesn't use clean numbers, don't expect your schedule to. Always leave a 20% buffer between your scheduled units of time.
If you want to master your schedule, stop fighting the clock. Recognize that our units of a period are a mix of ancient math, planetary physics, and atomic vibrations. They aren't perfect. They’re just the best tools we’ve built to stop everything from happening all at once.
Track your time for three days without changing your behavior. Just log it. You’ll probably find that your "hours" aren't nearly as long as you think they are, and your "minutes" are being wasted in gaps you didn't even know existed. Once you see the patterns, you can actually start to control them.