Today, I learned that:
Finally, we are about to have an international system of measures that will be based entirely on Mother Nature. I am of course talking about the International System of Units (SI system), which has its origin in 1875, when the two references for length and mass were decided. It has ever since grown to comprise seven base units, of which six are derived by using natural phenomena. See references #1, #2, and #3 below. The following illustration is contained in the last of those references, and it also develops the matter further in an elegant way:
However, the seventh base unit, the kilogram, is still an object manufactured in 90 % platinum and 10 % iridium. It is kept in a safe in Paris and has copies spread out over the world. There are several negative remarks that can be made to such a procedure, the difficulty of accessing the object, the wear and tear that the atmosphere exercises on the object, etc. So, if everything goes as expected, in November 2018, there will be a congress deciding to abandon the physical mass reference and substitute it with something based on non-changing conditions.
The new reference will be based on Planck’s constant. A highly precise balance operates on the principle of electromagnetic force compensation. In it, a weight on one side is balanced by the electrical force on the other. This electrical force is linked to Planck’s constant and can therefore be directly referred to as the new kilogram definition. See reference #4 below.
And while they are still at it, how about also changing the base unit from something which includes a prefix (as you know kilo means 1000) to a neutral one? My suggestions is that the seventh base unit should be named planck, abbreviated P, to which the normal prefixes would be used, when necessary. For instance, gram (g) would be mP (milliplanck) and the ‘metric’ ton, currently 1000 kg, would be 1 kP (kiloplanck). In the old CGM system of measures, there is a P which standards for Poise, the unit for dynamic viscosity, but in the SI system it has already been substituted by Pa.s (pascal-second), where 1 Pa.s = 10 P.
The photo below was taken in the strait of Kattegat on the Danish side on 2017-05-25, when I flew from continental Europe to Gothenburg. It shows the Danish wind farm close to the island of Anholt, one of the ten biggest in the world. Due to the altitude, it may be difficult to see, but each one of those small white spots is a wind turbine. See also reference #5 below.
A large Danish wind farm, located in the sea between Denmark and Sweden, close to the island of Anholt. Photo taken on 2017-05-25.
Since this time of the year is appropriate for many people in Europe to take vacation, what could be better than “sol, vind och vatten” (sun, wind, and water), which the fantastic Swedish song writer Ted Gärdestad described so well in reference #6 below?
And did you know that renewable energy is the cheapest one to acquire? According to professor Tomas Kåberger of Chalmers, it occurred already in 2016! An article describing that and many other interesting correlated facts can be found in reference #7.
… That’s what I learned in school !
Refs.:
1: International System of Units
4: Researchers developing a new balance for the new kilogram
5: Wind farm
What did you learn in School today? 