People are animals that measure things. Call us Man is the measure. We have a compulsion to calculate, and we have been inventing modern ways to do it for millennia. There is equipment that can measure this, from sphygmomanometers to spectrophotofluorometers. And nowhere, of course, is this more true than in science. Well, science and baseball.
Physicists build models to explain how the world works. This may be an equation similar to the ideal gas law: PV = nRT. This tells us, for example, that if we double the temperature (T) of a gas, all else being equal, its gas pressure (P) will double. However, to check whether the model is correct or at least useful, we need to get some real-world values and check whether the equation is true. Modeling and measurement, measurement and modeling – this is science in a nutshell.
Of course, today we have some pretty fancy instruments for this. But I’ll let you in on a little secret: with all of our frigid tools, measurement still comes down to comparison or counting. In this sense, little has changed since Noah built his ark based on a specification expressed in cubits – that is, the length of the human forearm from the elbow to the tip of the finger. Let me show you what I mean.
Length measurement
I’ll start with a measurement that everyone has used at some point: length or distance. It seems uncomplicated, right? If you want to know the length of a pencil, place it next to a ruler. There it is 18.7 centimeters. (Yes, we are on the right track in science This ruler page.)
Photo: Rhett Allain
Here you compare the length of the pencil and the length of the ruler side by side. (Of course, this raises another question: How do you know if the ruler you bought online is exact? That’s a whole other discussion about standards. We can save that for another day).
The craziest comparative measurement in history occurred in 1958, when a group of MIT students decided to measure the length of the Charles River Bridge. They had the shortest member of their group, Oliver Smoot (170 centimeters), lie down repeatedly, marking the entire length of the walkway with chalk, and found the bridge polished, “give or take an ear.”
(You can’t make this stuff up: Smoot became head of the U.S. National Institute of Standards and later the International Organization for Standardization. Smoot’s definition was changed in 2015 when photographic evidence revealed that by the age of 75, his height had decreased by 3 centimeters.)
Either way, it turns out that measuring length or distance by comparison is the most common method used in analog devices.
Other distance measurements
For example, what about time? One of the oldest time-measuring devices is the sundial, which in its known form was invented by the antique Greeks. It has a triangular blade, the so-called gnomonand a flat disk with numbers around the hours.
Photo: Rhett Allain