the center of the world (was Re: Check out O'Reilly's Open Source Convention Highlights)

Keith F. Woeltje kwoeltje at
Sat Jul 7 10:24:54 EDT 2001

Saw this on slashdot and thought of this thread. Here's what the Debian 
folks did. My trig is pretty rusty, so I'm not sure the method is correct.

digging-up-old-threads-to-put-off-real-work-a-few-minutes-longer-ly yours

Alex Martelli wrote:

> "Grant Griffin" <not.this at> wrote in message
> news:3B3B2DED.5303198A at
>     ...
>>Hey, who said anything about "world"?...
> Kernighan and Ritchie did (they were greeting it, I believe).
>>But now that you mention it, the US Midwest *is* pretty centrally
>>located on a "world" basis.
>>as-much-as-anything-else-on-this-sphere-<wink>-ly y'rs,
> An interesting exercise might be to define a *meaningful*
> "central location" -- one based on population distribution
> (or other geographical distributions of interest).
> After all, since tunas are unlikely to attend a conference
> on technical computer issues (given that you can tune a
> filesystem, but you can't tuna fish), "weighting" the vast
> aquaceous parts of the (approximate) "sphere" equally to
> the populated landmass may be a fine exercise in geometry,
> but doesn't make much sense otherwise.  As soon as you want
> to move from pure geometry to some kind of geography, I
> think some demographic issues must arise.  Even without
> considering demographics, at least some account could be
> taken of land vs ocean and maybe of land with/without
> permanent ice covering.
> Some data, ordered by-country, can easily be found for free
> on the web,
> for example.  Latitudes and longitudes of cities in various
> countries are also easily available, e.g. at
>  We can
> get a first approximation for a distribution of world human
> population by assuming a country's population is divided
> equally among its major cities.  This will require some work
> and supervision because of varying formats etc in the files
> being used -- or is there somewhere on the net that already
> gives me in a single readable file a lot of data boiled down
> to triples (population, latitude, longitude)?  Anyway, once
> I do have such a file, I can presumably find the "center of
> the world" (approximate) -- the one point on the Earth's surface
> that minimizes population-weighted sum of great-circle distances
> to 'population centers'.  Of course I could get different
> centers by choosing different weighing factors (country GNP
> rather than country population, for example).
> Hmmm, if the coordinates were on a plane, finding the weighed
> center would be trivial, but offhand I can't think of how to
> do it on a sphere's surface -- I guess there must be some way
> more suitable than just solving a generalized extremization
> problem -- can anybody suggest one...?
> Of course, there are enough degrees of freedom in the outlined
> procedure that it can probably be used for my real purpose, i.e.,
> proving that the relevant "center of the world" is within easy
> walking distance from my home and thereby convincing the PS^H^H
> O'Reilly to hold their next conference somewhere that's highly
> convenient for me...
> Alex

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