What does the French Revolution
have to do with the time NASA accidentally crashed a $200 million orbiter
into the surface of Mars?
Actually, everything.
That crash happened due to an error
in converting between two measurement systems,
U.S. customary units
and their S.I, or metric, equivalence.
So what’s the connection to the French Revolution?
Let’s explain.
For the majority of recorded human history,
units like the weight of a grain or the length of a hand weren’t exact
and varied from place to place.
And different regions didn’t just use varying measurements.
They had completely different number systems as well.
By the late Middle Ages, the Hindu-Arabic decimal system
mostly replaced Roman numerals and fractions in Europe,
but efforts by scholars like John Wilkins to promote standard decimal-based measures
were less successful.
With a quarter million different units in France alone,
any widespread change would require massive disruption.
And in 1789, that disruption came.
The leaders of the French Revolution didn’t just overthrow the monarchy.
They sought to completely transform society
according to the rational principles of the Enlightenment.
When the new government took power,
the Academy of Sciences convened to reform the system of measurements.
Old standards based on arbitrary authority or local traditions
were replaced with mathematical and natural relationships.
For example, the meter, from the Greek word for measure,
was defined as 1/10,000,000 between the Equator and North Pole.
And the new metric system was, in the words of the Marquis de Condorcet,
“For all people, for all time.”
Standardizing measurements had political advantages
for the Revolutionaries as well.
Nobles could no longer manipulate local units to extract more rent from commoners,
while the government could collect taxes more efficiently.
And switching to a new Republican Calendar with ten-day weeks
reduced church power by eliminating Sundays.
Adoption of this new system wasn’t easy.
In fact, it was a bit of a mess.
At first, people used new units alongside old ones,
and the Republican Calendar was eventually abandoned.
When Napoléon Bonaparte took power,
he allowed small businesses to use traditional measurements
redefined in metric terms.
But the metric system remained standard for formal use,
and it spread across the continent, along with France’s borders.
While Napoléon’s empire lasted eight years,
its legacy endured far longer.
Some European countries reverted to old measurements upon independence.
Others realized the value of standardization
in an age of international trade.
After Portugal and the Netherlands switched to metric voluntarily,
other nations followed,
with colonial empires spreading the system around the world.
As France’s main rival,
Britain had resisted revolutionary ideas and retained its traditional units.
But over the next two centuries, the British Empire slowly transitioned,
first approving the metric system as an optional alternative
before gradually making it offical.
However, this switch came too late for thirteen former colonies
that had already gained independence.
The United States of America stuck with the English units of its colonial past
and today remains one of only three countries
which haven’t fully embraced the metric system.
Despite constant initiatives for metrication,
many Americans consider units like feet and pounds more intuitive.
And ironically, some regard the once revolutionary metric system
as a symbol of global conformity.
Nevertheless, the metric system is almost universally used in science and medicine,
and it continues to evolve according to its original principles.
For a long time,
standard units were actually defined by carefully maintained physical prototypes.
But thanks to improving technology and precision,
these objects with limited access and unreliable longevity
are now being replaced with standards based on universal constants,
like the speed of light.
Consistent measurements are such an integral part of our daily lives
that it’s hard to appreciate what a major accomplishment for humanity they’ve been.
And just as it arose from a political revolution,
the metric system remains crucial for the scientific revolutions to come.
