Scientists have just made a major announcement. The standard unit of weight, i.e. kilogram is completely redefined.

The value of one kilogram will now not be defined by just a piece of metal, but it will be based entirely on a constant of nature. The weight will be the same.

This is actually the biggest revolution in the science of measurement since the French Revolution according to the beliefs of the scientists. The scientists said that now, the metric system will create such units will be for all people and all time.

Source- NSIT

But why this change? The lump of metal which actually defines one kilogram is a platinum-iridium which is stored in a Paris vault. If any slight contamination or some speculate enters it, the weight of the metal changes, causing the change in the value of one kilogram. But now, the kilogram will be defined by a calculation which will include the Planck’s constant (h). Not only Kilogram, but Ampere, Kelvin, and Mole are redefined too.

Source- The Verge