【AI前沿】All the Fancy Measuring Devices Used in Science Rely on Two Stone-Age Techniques

Rhett AllainScienceMay 22, 2026 7:00 AMAll the Fancy Measuring Devices Used in Science Rely on Two Stone-Age TechniquesThe many methods we use to gather data ultimately boil down to either counting or comparing.Photograph: Muhammad Labib AdilahCommentLoaderSave StorySave this storyCommentLoaderSave StorySave this storyHumans are animalsthat measure things. Call usHomo mensura.We have a compulsion to quantify, and for millennia we’ve been inventing new ways to go about it. For anything you can think of, there’s a device to measure it—from sphygmomanometers to spectrophotofluorometers. And of course nowhere is this more true than in science. Well, science and baseball.Physicists build models to explain how the world works. It might be an equation, like the ideal gas law: PV = nRT. This tells us, for example, that if you double the temperature (T) of a gas, all else equal, its gas pressure (P) will double. But to see if the model is legit, or at least useful, we need to get some real-world values and check whether the equation holds. Modeling and measuring, measuring and modeling—that’s science in a nutshell.Of course, today we have some pretty fancy instruments for this. But I’m going to let you in on a little secret: With all of our cool tools, measurement still comes down to either comparison or counting. In that sense, it hasn’t changed much since Noah built his ark from a spec sheet in cubits—the length of a human forearm from elbow to fingertip. Let me show you what I mean.Measuring LengthI’m going to start with a measurement that everyone has used at some point: length or distance. It seems simple, right? If you want to know the length of a pencil, you lay it down next to a ruler. There, it’s 18.7 centimeters. (Yeah, in science we’re onthatside of the ruler.)Photograph: Rhett AllainWhat you’re doing here is comparing the length of a pencil and the length of a ruler side by side. (Of course this brings up another issue: How do you know if that ruler you bought online is accurate? That’s a whole other discussion about standards. We can save that for another day.)The nuttiest comparison measurement ever took place in 1958 when a group of MIT undergrads set out to find the length of a bridge over the Charles River. They had the shortest member of their group, Oliver Smoot (5′ 7″, or 170 centimeters), lie down repeatedly, marking the sidewalk with chalk, all the way across, and found the bridge to be 364.4 smoots, “give or take an ear.”(You can’t make this stuff up: Smoot went on to become head of the American National Standards Institute and later the International Organization for Standardization. The definition of a smoot was revised in 2015, when photographic evidence revealed that at age 75, his stature had diminished by 3 centimeters.)Anyway, it turns out that measuring length or distance by comparison is the most common method used in analog devices.Other Distance MeasurementsFor example, what about time? One of the oldest timekeeping devices is the sundial, which in its familiar form was invented by the ancient Greeks. It has a triangular blade, called agnomon, and a flat disc with numbers around the circumference for hours.Photograph: Rhett AllainAs the sun moves across the sky, the shadow cast by the gnomon will move. But how do you turn that shadow into time? You got it—you measure the distance of the shadow from the noon position. The sundial above is pointing to 2:10 pm.(Interesting footnote: The hour labels had to be inscribed differently from city to city because the shadow changes by latitude and longitude. If you moved from Sparta to Athens and took your sundial with you, you’d be five minutes late to class at the Lyceum.)Here’s another time-measuring device you might have seen, which shows the same time, 2:10, in a different way:Photograph: Rhett AllainI love this old clock. It’s fun to remember that “IBM” stood for International Business Machines, which weren’t just computers. Anyhow, you read the time from the location of the hands. Yup, that’s a distance measurement—the information is conveyed by how far a hand has traveled around the dial. But wait! There’s more! Here are some other things that measure using distances:Clockwise from top left: antique postal scale, analog force gauge, ammeter for measuring electrical current, triple-beam balance, and compass.Photograph: Rhett AllainThat force gauge above, for instance, has a calibrated spring inside. When you hang a mass on it, the spring stretches proportionately to the force exerted, and the length of extension indicates how many newtons of pulling force were applied. The result is displayed as a distance on a dial.Sometimes we just do comparisons without a distance measurement. Here is a balance scale. You put an unknown mass on one side and add known masses to the other side until they’re equal. That’s how assayers measured gold during the California Gold Rush.Photograph: Rhett AllainWhy didn’t they use a spring scale, which would be