Comment by FabHK

What we'd like to have:

1. Use SI seconds

2. Keep in sync with earth rotation

3. Avoid leap seconds

Pick any two:

- UT1: 2, 3 (not 1) [https://en.wikipedia.org/wiki/Universal_Time]

- TAI: 1, 3 (not 2) [https://en.wikipedia.org/wiki/International_Atomic_Time]

- UTC: 1, 2 (not 3) [https://en.wikipedia.org/wiki/Coordinated_Universal_Time]