Right now, somewhere on the earth, it is still yesterday, or already tomorrow. Therefore, if one got in a supersonic jet, and flew to whatever place was the farthest back in the solar time zone, or furthest ahead, aren’t you indeed traveling in time? The speed of sound is 67,800mph in air. That’s pretty damn fast. Now I know this isn’t the traditional concept of time travel. But it is sort of a form of time travel isn’t it?
Yes. We are all always travelling foreward through time.
Dang! Someone pumped up the speed of sound when I wasn’t looking! Watch out for the Concorde: it exceeds escape velocity!
Sorry about that… IIRC, the speed of sound in air at sea level is somewhere around 700 mph.
I hope you’re kidding.
In case you’re not here’s the scoop.
Time zones and what not are a purely human convention based on the earth’s rotattion. They’re are meaningless in terms of science. Simply consider the ENTIRE earth as at the point we’ll call “now”. Different places may call “now” 9:00 a.m. or 3:00 p.m. Doesn’t matter.
To travel in time you need to get to “before” or “later”. To do that consider travelling to a time when the earth is either further along (before anyone else arrives there) or further behind its orbit around the sun.
In the end you’ll find it nearly if not absolutely impossible. The few (albeit questionable) methods for true time travel would almost certainly kill you in the attempt if not outright blast the earth into oblivion (IIRC one method would require the energy equivalent to turning the mass of Jupiter into energy thereby incinerating you as well as the earth).
I looked up the speed of sound before I posted an it was listed as 1130 feet per second. I seriously screwed up my math though. Im not sure if I have my formula correct yet or not.
[li]60 seconds X 60 minutes = 3600 seconds in an hour[/li][li]1130 fpS X 3600 seconds = 4,068,000 feet per hour[/li][li]4,068,000 fpH divided by 5280 feet = 770.45 miles per hour[/li]
I think I did it right! Did I? Dear God I hope so.
Like Jeff_42 said…time zones are irrelevant (so are clocks, calendars, etc.)…these are just our arbitrary ways to measure time. You’re still moving forward through “Time” at a normal rate. (similar example…if you change the time on your watch, you have not “time travelled”)
But hey, if you travelled around the world at 67,800 mph, you would experience a few nanoseconds of time dilation relative to the rest of us. (I’m sure someone will correct me on this estimate…I did not run the time dilation equation.)
BTW, yes, the speed of sound in air is around 770 mph 
(depending on local atmospheric conditions).