In my opinion, We couldn't really "Change" the timezones. Different sides of the hemisphere.. It might be day there.. but it's night somewhere else lol.
Yea that means kids in california would be going to school when its still dark outside and wont be light up till about lunch
and i know this is already said but 1 nation wouldnt work, would 1 person run the whole world? would a committee, what if the committee couldnt get along? it wouldnt work