Sorry about the delay — I was away from e-mail for a while.
On Apr 3, 2015, at 7:27 PM, Keith F. Lynch <kfl@KeithLynch.net> wrote:
Dan Asimov <asimov@msri.org> wrote:
1. Suppose Earth is a perfect sphere and that each time zone is a perfect spherical lune of angle 2?/24 that takes 1 hour to traverse an hour of time.
I'm assuming the question mark was meant to be pi. Non-ASCII characters are turned into question marks on this list, at least in its digest form. This is presumably because there are multiple incompatible character sets which senders might be using, and the digest header can specify at most one of them.
Yes, I meant 2pi/24.
Set a stopwatch to begin when it is first mm/dd/yyyy anywhere on Earth, and stop the watch when it is no longer mm/dd/yyyy (where mm/dd/yyyy is an arbitrary day of 24 hours' length).***
QUESTION: How long did the stopwatch run for? (Mental math only.)
Twenty-five hours. The default International Date Line is exactly opposite the prime meridian, hence is in the middle of a time zone, not on the border between two of them. So some clocks are 12 hours ahead of Greenwich when others are 12 hours behind.
Nope.
2. Same question, but with time zones as they actually are. (Any references and writing implements allowed.)
Based on the time zone map in the current World Almanac, 27 hours.
I'm not sure of the exact answer, but this can't be right. --Dan ***Just to be clear: "mm/dd/yyyy is an arbitrary day of 24 hours' length" in each time zone.