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.
