[fengb]

Mole was just redefined as exactly 6.02214076e23 — the number of Si-28 atoms in a perfect 1 kg sphere. This was an intentionally check against the kibble balance measurement.

More info from an older Veritasium video: https://www.youtube.com/watch?v=ZMByI4s-D-Y

[mherdeg]

Yeah, I had totally missed that a change was in the works to redefine Avogardo's number as an exact number with no uncertainty. Pretty cool.