Re: Having a single time is a nonsense
Nah. We're human beings--we'll adapt.
Abolish "Mean Solar Time", and move to TAI ("Atomic" time). I can refer to any future time, correctly and accurately, always. Time goes forward at a fixed rate, all the time.
Then drop time zones, and move to the 24-hour time format. The world is a big place, and there's plenty of understanding in it: Australians just happen to get up at 18:00, that's all. And no bloody "Daylight savings", neither.
Then drop relative time: every time is expressed as an absolute, and people become good at mental arithmetic so we can express durations, and swiftly add them together, or recognise time periods such as 86400 seconds equating to a day.
Now stop insisting on having significance of day and night: time is used at whatever interval suits, and day and night are merely observable events. Efficiency may very well be improved. The problem of natural illumination can be solved, somehow *, but in the event that it can't, then sunrise and sunset are merely accurately-recorded points on the absolute timeline, by which means relative offsets may be expressed for the purposes of coordination.
Then switch to a decimal system of time units, of suitable complexity to allow very accurate time scales but of sufficient manageability for everyday use.
Not interested? But it's the future! Ah well, thought I'd just suggest it ...
* I'm blind, so I don't have this problem, happily.