[LEAPSECS] Tripping over the International Date Line

[Rob Seaman]

On Mar 7, 2007, at 1:04 PM, Zefram wrote:


> As I recall (from an English translation) the wager was mooted  

> merely as

> "eighty days" but then formalised as returning to the club at his  

> usual

> time of day on a specified calendar date.

>

>>                                          One could argue that it

>> took Fogg 81 days shortened days.  Then, it would have been

>> preferable to travel westward and be able to take 80 longer days.

>

> I think that's a perverse meaning of "day".  In the absence of DST or

> other changes (the story predates DST), "day" in a civil context and

> without any qualifier must be taken to mean civil days at any fixed

> location.  Which location doesn't make any difference, of course, when

> using the day only as a unit of duration.  You'd have a hard time  

> arguing

> in court to measure solar days at a moving location.


All locations are moving.  It matters how fast.

We can likely all agree that a rapidly moving astronaut in LEO does  
not "really" experience a day every ~5000 SI seconds.

But the most bedrock (literally) definition of the word "day" flows  
from colloquial usage such as "as night follows day".  The sun rises,  
the sun sets, the sun rises again.  I think you would have a hard  
time arguing that the relatively slow moving Fogg did not "really"  
experience 81 complete days on his journey.  That a stationary  
fiducial clock was specified as arbiter of the wager seems eminently  
prudent, however.

Both interpretations are sound.  The International Date Line is a  
social construct created to minimize the intrinsic confusion of the  
universe.  We should hope the same from our other standards and  
policies.

Rob