We already have way too many time standards, including:
- TAI, time based on an atomic clock, which ignores all motion of the Earth
- UT0 and UT1, time based on precise measurement of the Earth’s rotation
- GPS, the time standard used by GPS satellites
- UTC, the standard used in computing, which is like TAI but with leap seconds to keep it in sync with Earth
- TDT, TBT, TCB, and TCG, which are all even worse
This leads to all kinds of little headaches, particularly for programmers. For example, the clock in your smartphone’s GPS is 16 seconds out of sync with the phone’s system clock. This is because the system clock uses Coordinated Universal Time (which has leap seconds), but GPS time doesn’t. They were in sync in January of 1980 and probably never will be again.
Posts tagged ‘TDT’