Most people probably missed the big celebration May 20.

That was World Metrology Day. And before you run off to look up the word, it’s the study of measurement.

The day took on even more significance than normal because it was the day a new standard measurement for kilogram was adopted. And it was long overdue (whether you realized it or not despite the lack of fireworks displays and parades).

You see, the kilogram (2.2046 pounds) has been defined since 1889 by a small cylinder called the IPK, the International Prototype of the Kilogram, made of 90 percent platinum and 10 percent iridium and kept under two bell jars, in a special climate-controlled vault in France. And kilogram is the only one of the seven SI (International System of Units) which was still defined by a physical object, rather than a physics constant.

There are copies of the IPK in various locations around the world and they are periodically sent to France to compare them with the base unit. But over the years, the mass of the copies has varied from the original and no one knew if the original was gaining mass or the copies were losing it.

So, since physical objects apparently cannot be relied on to remain constant, and scientists demand the utmost accuracy, a new method of defining mass was needed.

To give you an example of how much accuracy scientists demand, the meter has been defined as the distance light travels in a vacuum in 1/299,792,458 second and a second is determined to be the time it takes a cesium atom to oscillate 9,192,631,770 times. Imagine even trying to measure these.

Well, now the kilogram is going to be defined based on the Planck constant, the ratio of energy to frequency of a photon and metrologists will have many fun-filled years checking the IPK to see how it varies from the Planck constant value. And they will probably be able to determine if the copies are really losing mass or the IPK is gaining. What laboratory frivolity will ensue.

Of course, all this change will have no noticeable effect on 99.9999 percent of the world population because a kilogram of apples will still be a kilogram of apples, unless you’re in the United States or one of the only two other nations in the world still using the English system of weights instead of the SI (metric) system, where apples come in pounds.

Terry Quinn, emeritus director of the International Bureau of Weights and Measures, says while the new measurement may look complex, the new system can actually be easily understood by anyone since he himself built a simple balance out of Legos that can measure within 5 percent against the Planck constant.

“School children will be able to have immense fun with this,” he said. Yeah, right.

The world has come a long way since the measurement of a yard was defined by the distance from one’s nose to the end of his (or her) sideways-outstretched arm.

But here’s a potential glitch in all this accuracy seeking. Suppose, at some point in the future, it is discovered the Planck constant isn’t constant after all, that some anomaly in the space/time continuum has altered it, or that scientists of today didn’t really quite get it right anyway.

After all, look at how far off they were with the meter for a few centuries.

If that happens, will the metrologists come to the people, hats in hand, professing their inadequacy or will they simply pass off the errors as a lack of sufficient evidence at the time the calculations were made?

Not to worry. We can always blame the politicians and too many committee hearings.

And be sure to mark off May 20, 2020, because you won’t want to miss the festivities.

Information for this column was provided by ScienceAlert.com. Chuck Witt is a retired architect and a lifelong resident of Winchester. He can be reached at chuck740@bellsouth.net.