A few weeks ago I found myself on an interesting journey in space and time. I set off on a Friday, travelled through Thursday, Friday, Saturday, Friday, Saturday and finally arrived about 14 hours later on the Friday before I'd set off. I did all of this without a DeLorean DMC-12 or a little blue box. All it took was an international flight and a series of complicated time zone boundaries.
My flight was from Auckland, New Zealand to Vancouver, Canada and it set off around 8pm local time on a Friday. As you can imagine, this flight goes from the southern to northern hemisphere across the Pacific Ocean and so crosses the International Date Line. Actually, because various island nations have chosen to redefine which time zone they are in, my flight crossed the International Date Line five times! Before I go any further I had better provide a diagram showing the middle of the flight. It will help.
My journey in space and time CREDIT: Stuart
Point B - my first crossing of the date line - occurred at about 10:50 UT Friday. That meant I went from 23:50 local time (UT+13) Friday to 23:50 local time (UT-11) Thursday. Ten minutes later the local time clock rolled over into Friday. I reached point C at 13:17 UT Friday which was now 03:17 local time (UT-10) Friday and crossed the date line again so went to 02:17 local time (UT+13) Saturday.
At around 15:00 UT Friday I reached point D - the date line - so went from 04:00 local time (UT+13) Saturday to 04:00 local time (UT-11) Friday. After crossing the equator I fell asleep for a while as I was tired and the in-flight map isn't the best thing to keep you awake even if you are time travelling. Despite being asleep, a little later I crossed the date line at point E going forward to Saturday again and then back to Friday when I crossed the date line at point F.
After 11000 km, I eventually landed in Vancouver sometime around 2pm local time on the Friday. That meant I arrived roughly 6 hours before my departure time. This sort of time travel is no good though as it left me seriously jet-lagged. Still, I recovered and no grandfathers were harmed.