All Advanced Measuring Instruments Used in Science Rely on Two Stone Age Methods.

People are animals who measures things. Call us Man is a measure. We have a compulsion to calculate, and for thousands of years we have been inventing new ways to do it. For everything you can think of, there is a measuring instrument – from sphygmomanometers to spectrophotofluorometers. And certainly nowhere is this truer than in science. Well, science is baseball.

Physicists create models to explain how the universe works. It can 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 things being equal, its gas pressure (P) will double. But to see if the model is valid, or useful, we need to find the real facts and check if the equation holds. To measure and to measure, to measure and to compare—that is science in a nutshell.

Of course, today we have the best tools for this. But I’ll let you in on a little secret: With all our great tools, measurement still comes down to comparison or calculation. In this sense, it hasn’t really changed since Noah built the ark from a small piece of cloth—the length of a man’s forearm from the elbow to the finger. Let me show you what I mean.

Measuring Length

I’ll start with a measurement that everyone has used at some point: length, or distance. Seems simple, right? If you want to know the length of the pencil, you put it down next to the ruler. There, it is 18.7 centimeters. (Yes, in science we are moving that side of the ruler.)

Photo: Rhett Allain

What you are doing here is comparing the length of the pencil to the length of the ruler side by side. (This brings up another issue: How do you know if the ruler you bought online is the right one? That’s another discussion about standards. We can save that for another day.)

The most intriguing comparison was made in 1958 when a group of MIT undergrads set out to measure the height of a bridge spanning the Charles River. They had the shortest member of their team, Oliver Smoot (5′7″, or 170 centimeters), lay down again and again, writing chalk along the way, the whole way, and found that the bridge was 364.4 smoots, “give or listen.”

(You can’t make this up: Smoot became the head of the American National Standards Institute and later the International Organization for Standardization. The meaning of smoot was changed again in 2015, when photographic evidence showed that at the age of 75, his height decreased by 3 centimeters.)

However, it seems that measuring height or distance relative to the method is most commonly used in analog devices.

Distance Measurements

For example, what about time? One of the oldest instruments for keeping time is the sun, which in its most famous form was invented by the ancient Greeks. It has a triangular leaf, called a gnomonand a crumpled disc with numbers spinning around for hours.

Photo: Rhett Allain