Before the 16th century, clocks were horrible.
Typically there was one large mechanical clock in the center of any town which would be reset
daily, but by the end of the day these would be off by as much as 20 minutes.
Time was but a rough estimate, but nobody really had a problem with this since there
was no expectation of accuracy.
At the time, there was no real need for accurate clocks in daily life.
The need for more accurate clocks came about when explorers started to voyage across the
world by sea.
The best way for ships to calculate their locations was to have two clocks—one with
the time of the ships origin and one with the current time as calculated by a sundial.
With every four minutes of difference between the two times, you would know that you had
travelled about 68 miles (one degree of longitude).
The problem with this method was with the accuracy of the clocks.
Much like the clocks in town centers, the origin clocks were off by up to 20 minutes
by the end of one day, so this method was useless after a few days of travel.
This stifled exploration, so governments around the world offered prizes equivalent to millions
of dollars to anyone who could design an accurate clock.
That’s where Galileo comes into play.
Legend has it that in 1583, a 19 year old Galileo was bored while attending prayers
at the Duomo of Pisa, so he started watching the hanging lamps up above.
He noticed that, as they swung back and forth, the lamps always took the exact same amount
of time to complete one swing.
No matter if they swung one foot or one inch, the swing would take the exact same amount
of time.
58 years later, this property was used to make a pendulum clock.
Properly weighted, a pendulum could be designed to swing once per second, and the clocks would
use the swinging weight to keep time.
This clock was amazingly accurate—a week after being set, it would only be off by as
much as a minute.
100 years after it’s invention, the pendulum clock was in every house.
Many argue that, without this invention, the industrial revolution would not have been
possible.
You could now tell someone to meet you at an exact time and they would actually be there
at that time.
Ships could now use these accurate clocks for accurate navigation, and this meant that
it was no longer risky to send ships regularly to buy and sell goods across the world.
Accurate time also changed the way people worked.
Before the pendulum clock, people only worked for results—by the end of the day they were
paid for how much they made instead of how much they worked.
With the clock workers worked for an amount of time, and they were paid by the hour.
With the new production boom, manufacturers demanded a method of fast and cheap shipping,
and so the railroad was born, but this introduced a new problem.
Time was still dictated by the sun.
Each town would calculate the local time based upon the location of the sun in the sky, but
this meant that from one town to the next, the time would be different.
In one town it could be 8:10 and in the next town over it would be 8:15.
Both times were correct for the two locations, so this didn’t really cause a problem since
it would take hours to get to that next town over.
Across the United States, there were thousands of different local times.
However, with the newly invented railroad, people could get from one town to the next
quickly, but nobody knew when trains really left since everyone used a different time.
The railroad might use one time, while the origin town would use another, and the destination
town would have a completely different one.
Britain solved this problem by creating a standardized time—Greenwich Mean Time—and
transmitting that time across the country by telegraph.
The US decided that, with it’s huge size, a standard time zone would not work, so four
different time zones were mapped out.
Much like Britain, the standard time would be transmitted across the country by telegraph.
The implementation of this new time zone, however, created one of the stranger days
in human history.
The new eastern time zone ran four minutes behind the time that New York had been using,
so on Sunday, November 18, 1883, the clocks struck noon, then four minutes later, the
clocks struck noon again as the new time standard was implemented.
The next great innovation in timekeeping came towards the beginning of the 20th century.
Pierre and Jacques Currie, two French physicists, noticed that when electricity was applied
to quartz, it vibrates at a incredibly stable rate.
Knowing that quartz vibrates 32,768 times a second, clockmakers used this crystal to
make incredibly accurate clocks.
These quartz clocks were able to go a month only loosing or gaining 15 seconds.
Just as the pendulum clock allowed for the industrial revolution, the quartz clock allowed
for the technological revolution.
Without quartz clocks, modern computers would have been impossible.
An accurate internal clock is needed to coordinate all the different microprocessors.
With these new accurate clocks however, people also began to notice that the earth’s rotation
wasn’t all that regular.
It deviated by a few seconds here and there.
In the 1950’s the first super-accurate atomic clocks were built—measuring time based upon
the decay of atomic elements, and this allowed an International Conference of Weights and
Measures to change what time was in 1967.
They decided that a day was no longer one rotation of the earth—a day was now 86,400
atomic seconds.
Since the time it takes for the earth to rotate is not exactly 86,400 atomic seconds, we make
up for this by having leap days and leap seconds every once in a while.
The atomic-clock also allowed for nano-second accuracy, and this is actually pretty important
for many modern technologies—most notably the GPS.
GPS works by asking three different satellites the time based upon their onboard atomic clocks.
When the answer comes back, each time will be slightly different on a nano-second level
due to satellites being at different distances and the request for the time going out at
only the speed of light, so the GPS, knowing the location of the satellites based upon
their extremely predictable orbits, can figure out where it is.
So that’s how time developed.
Hopefully you now see how the human conception of time was essential for the development
of our modern world and can still be called one of humanity’s greatest inventions.