On Interstate 19 in Arizona, which connects the city of Tucson with the Mexican border at Nogales, the signs are in kilometers. According to CNN, America’s only metric highway is a remnant of the Jimmy Carter era, when the idea of adopting the metric system in the United States was briefly taken seriously.

Every country in the world – almost – uses the metric system. And everyone knows why: the math is easier. All you have to do to convert between units is move the decimal point. It’s the world’s official system of measurement. Our American inch is defined in statute as precisely 2.54 centimeters.

The metric system is the one part of the French Revolution to sweep the world. Today, the only remaining non-metric countries are Liberia (founded by American slaves who returned to Africa), Myanmar (formerly known as Burma), and the United States.

My late friend Dave Alvernaz once suggested to me that the metric system hadn’t caught on here because it lacked the conceptual equivalent of a foot. Your foot is always there at the end of your leg, he pointed out, available to stick into a box or pace off a room. Three of them make a yard, and most of us are between five and seven feet tall. It’s a utilitarian measurement, based on the human body.

The metric system is based on the size of the Earth. The original definition of a meter was one ten-millionth (10-7) the distance along a meridian from the equator to the pole. Because not even this distance is constant (Earth bulges in different places), the official definition of a meter has since been tied to the speed of light. This is important to scientists and engineers seeking exact measurements of small distances on the atomic scale and large distances between the planets and stars.

All space missions have used the metric system since the loss of the Mars Climate Orbiter in November 1999. Designed to orbit Mars and monitor its weather, the ship burned up in the Martian atmosphere. According to Wired magazine: “A NASA review board found that the problem was in the software controlling the orbiter’s thrusters. The software calculated the force the thrusters needed to exert in pounds of force. A separate piece of software took in the data assuming it was in the metric unit: newtons.”

The new National Geographic Network Series Mars, set in the near future, uses entirely metric units. When the crew landed 75 kilometers from base camp, I had to calculate: “Okay, so a little less than fifty miles…”

Based on a decimal fraction of the size of the Earth, the metric system makes no more intrinsic sense on Mars than miles and feet. But it’s the easiest system to use, and it’s already the one in use by a majority of humankind. Perhaps if we had listened to Jimmy Carter 40 years ago, the Mars Climate Orbiter would not have crashed, and I would know my height in centimeters.

Like most Americans, I think in inches, feet and miles. Using the metric system is like learning a new language, something else Americans are notoriously reluctant to do.

The car culture, too, has its own language and patterns of thought, which make it difficult to change. We think of longer distances not in terms of miles but driving times: Bangor is two hours from Portland and four from Boston. It’s assumed that we are not talking about airplanes or bicycles. Car travel is part of our unspoken collective consciousness.

When I stopped using a car as my primary form of transportation, I found that I thought about the pattern of the day differently. How long did it take to walk to the bus stop? What did I need to take with me? How was the weather? When did the last bus leave downtown? What time did the sun set?

I recently saw the film Arrival. It was ostensibly about aliens but it was really about language. With a nod to Kurt Vonnegut, the film postulates that if humans can learn the aliens’ language deeply enough to think in it, they can see the Universe from a different perspective. Language drives perception, as much as vice versa.

I thought about that in the days after watching the film. And I thought that if we could begin to talk about cars and time and distance differently, without all the popular assumptions, we could perhaps begin to conceive of another way to live.