If there is evidence of a new international agreement on the definition of the SI second on both the BIPM and NIST websites, then the market resolves immediately.
Any redefinition in which there is a primary optical frequency standard and secondary cesium microwave standard or in which the standard is a weighted average of optical and microwave frequencies will resolve Yes.
1,000
3.00
Yes, but not by 2030. Took >100 years to redefine the kilogram. There must be a dire pressing need to change a standard, and I don't think such a need will aggregate before 2030.
@YaroslavSobolev There's already a roadmap in place for an optical redefinition, since optical standards perform at an accuracy and precision level 100x greater than microwave standards. This is mostly a question of 1) how quickly the required technical hurdles can be achieved, e.g. sufficient comparisons below 5e-18 fractional frequency difference and others, and 2) whether a consensus can be formed on which optical standard to use, e.g. Sr, Yb, other.
@YaroslavSobolev it has been a while already though. Optical atomic clocks are already in fairly widespread use, we're just not allowed to call time intervals based on them "seconds".
I agree 2030 may be too soon though. We don't have a consensus on which atom to use yet. Be more optimistic about 2040 maybe.