I used to live next door to one of the guys working on the KG. Very smart guy! Basically from what I gather, weight is the last unstandardized unit of measure

I used to live next door to one of the guys working on the KG. Very smart guy! Basically from what I gather, weight is the last unstandardized unit of measurement at the moment and the problem derives from finding something that has constant mass. Apparently it's pretty near to being solved though, I believe their project was sold to Canada last year though.