Till now, the only definition of the kilogram the books contain is of a certain cylinder containing 90% platinum and 10% iridium. That chunk of mass is called the International Prototype Kilogram (IPK) or the Le Grand K. But what happened yesterday is something so subtle, that it is actually too grand to be comprehended in just a moment. This subtle change is actually going to change a lot of Physics!
On the historic day of 16 November 2018, Scientists voted to change the definition of the Kilogram. The new definition will use Planck’s constant, the speed of light and atomic frequencies.
This change of definition has been brought about due to 2 primary reasons:
- A standard should be universally accessible and that it should be a fixed quantity. The Le Grand K was neither accessible to all and neither fixed.
- It was being observed that either the IPK or its replicas around the world were having a change in its dimensions. On further investigation, it was found out that the existing mass scale, based on the IPK, appeared to have shifted by 30 parts per billion.
Let me tell you, that this shift could be a very small amount for you, but that actually a very significant amount at the higher level, and especially in the field we the work in scales of micro and nano. An error at that level does have the potential to kill you.
The other thing that all have pointed out as a problem and as a applaud was that the kilogram was the only measurement that had the physical basis, that too since its establishment in 1879.
Thanks to Kyle Hill of Because Science, I have a pretty good idea of what a kilogram is. Here’s the link to his video streamed today in which he describes what a kilogram would be now.
(Please follow him on social media to watch more of his amazing content. He has got an amazing profile to back it all up.)
What he says is that mass will be now ‘quantum-defined’. The calculation though is a bit off, so I will be correcting the value of frequency to 135,639,248.96521320 × 10⁴² Hz
And here’s a video he recommends to be watched. Follow Veritasium to know more of the process to define the other things needed for defining mass.
Don’t worry, this won’t change what the kilogram is for you. But what will change is the approach to every other quantity associated with mass, i.e. kilogram! And when the approach changes, everything around it will change. This single change might bring about major revolutions, as we should see in the future.