Primal Science
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The Constants of Physics
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n the world of physics, there are quantities that we call ‘physical constants’ or just ‘constants’. Let's define what a physical constant is and learn what makes it special. A physical constant is a physical quantity that's both universal in nature and completely constant in time. Let's break down each part to make some sense out of it. First off, a physical constant is a physical quantity: an amount, number, or measure. As an illustration, picture some apples on the floor. Your friend asks you to tell him the exact number of apples. You count them and tell her there are five apples. Therefore, your quantity is five. It's simply how many of something there is. Next, a physical constant is ‘universal in nature’, meaning, in this context, that the constant occurs absolutely everywhere. Here's a quick example. A sports league puts a new rule into effect that applies to every
In 1849, French physicist Armand Fizeau used this method to achieve the first terrestrial measurement of the speed of light. Encyclopaedia Britannica/UIG Via Getty Images
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single division. Since it applies to every part of the sport, the rule would be universal. So if a constant is universal in nature, it means that it occurs throughout nature, with no exceptions. Finally, we have ‘constant in time’, meaning that the constant never changes — it had the same value 10 years ago that it has now and will have the same value 10 years hence. In fact, the constant will have the same value for the rest of eternity! That can be hard to conceptualise, but it's true of the physical constants. Let's put this all together. A physical constant is a measurement (of something) that is true EVERYWHERE (universal) and ALWAYS (constant in time).
It turns out that there are 26 fundamental physical constants that define our Universe …
