Definition of kilogram to change

https://www.bbc.co.uk/news/science-environment-46143399

The kilogram, like the pope, is infallible

The Kibble balance, as it has become known, has an electromagnet that pulls down on one side of the scales and a weight - say, a kilogram - on the other.

The electrical current going through the electromagnet is increased until the two sides are perfectly balanced.

But - what the article fails to mention is that the kilogram is the unit of mass, not force. The unit of force is the newton.

It seems what they've come up with is dependent on the gravitational pull (of the earth) at the location where the apparatus is placed. And the Earth's gravitational pull may vary.

The new system, if it is adopted, will allow anyone with a Kibble balance to check their weights anytime and anywhere, according to NPL's Dr Ian Robinson.

Like on board the International Space Station, or on the surface of the Moon or of Mars? Or by the shores of the Dead Sea, or on top of Mount Everest?

I'm sure this has all been thought of - it's basic high-school physics. But it isn't made clear, at least not to me.

https://www.bbc.co.uk/news/science-environment-46143399




But - what the article fails to mention is that the kilogram is the unit of mass, not force. The unit of force is the newton.

It seems what they've come up with is dependent on the gravitational pull (of the earth) at the location where the apparatus is placed. And the Earth's gravitational pull may vary.

Like on board the International Space Station, or on the surface of the Moon or of Mars? Or by the shores of the Dead Sea, or on top of Mount Everest?

I'm sure this has all been thought of - it's basic high-school physics. But it isn't made clear, at least not to me.

That seems to be a typically poor article from the BBC. There's a much clearer explanation in the Wikipedia article on the kilogram. That makes it clear that:
(1) The balance described in the article has nothing to do directly with the new definition of the kilogram. That comes from specifying the value of Planck's constant rather than measuring it, which has the effect of fixing the size of the unit of mass, and
(2) The use of these sensitive balances to measure the mass of an object with the new definition has to be accompanied by a separate measurement of the local acceleration due to gravity, which varies in time and space for a number of reasons, including altitude:

https://en.wikipedia.org/wiki/Kilogram#R...ember_2018