Get rid of political time-zones and DST and simply define 6:00am to be sunrise world wide. Each day starts at 6am and counts from there.

(If you are really brave let the length of the hour vary by latitude so that sunset is always at 6pm as well. In the winter up north the night hours are simply longer than the daylight hours. But this is too enlightened I think.)

We have the tech to do this. The first one is very practical. What time is it? How many hours since sunrise in this location +6?