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Sunday 21 April 2024

Mysterious latitude and longitude coordinates

There's the coincidence of the Pyramid of Giza's latitude being a very similar-looking number to the speed of light. It's nonsense of course, because when the Pyramid of Giza was being built (roughly 2600BCE):

  • No-one knew that the earth was round (so the concept of latitude didn't make any sense). It was more than 2000 years later Eratosthenes calculated the circumference of the earth (around 200BCE). He also made a map that connected the Atlantic Ocean with the Gulf of Arabia, and had the Equator substantially south of all of Africa.
  • No-one described angles in degrees, only ratios of lengths or ratios of quadrature (so describing a latitude in degrees wouldn't have been possible). Angles were probably Babylonian (2000 years later); Aristarchus of Samos (2300 years later) is the first writer we know who used them.
  • They didn't have decimal numbers; they didn't even have fractions with numerators. It's only in the Middle Kingdom period of Egypt (2000BCE, about 600 years later) that we see fractions of any kind.  Even then they couldn't represent 2/3 other than saying (1/3 + 1/3, or 1/3+1/5+1/12+1/20). It was the height of mathematics six centuries later than the Pyramid of Giza to be able to say that 1/5 + 1/12 + 1/20 = 1/3. So they wouldn't have been able to represent 29.979.
  • The length of the metre was defined as being the distance travelled by light in 1/299792458 seconds. That is, we chose that the speed of light would be that in 1983. If we had chosen 1/299792459 instead, presumably the great pyramid would have shifted north a bit. (I suppose some physicist might have been playing a prank on the world by making the speed of light match the latitude of the Great Pyramid of Giza. But that's not a mystery then, and it doesn't involve ancient aliens. It just involves a physicist with a sense of humour.)
    • Actually, the metre was defined before that. One of the complaints of the French revolution peasants was the inconsistent measures imposed by their pre-revolution feudal lords, who would change the size of measures when they were buying vs selling. So they defined the metre by saying "a metre is one ten-millionth of the distance from the equator to the north pole via Paris." They knew that the Earth wasn't completely round, and it solved the problem that they had, but they still got it a bit wrong anyway.
    • Before that, a metre was the length of a seconds pendulum -- a pendulum that swings every two seconds is roughly a metre long, as long is it only swings a little bit and the flexibility of the pendulum arm doesn't count.  Anyway, yes, the ancient Egyptians had pendulums, but they didn't have the concept of seconds. They probably had some way of dividing up time into units smaller than an hour using water clocks, but nothing as small as minutes. They didn't know that pendulums swung at a constant rate, that wasn't until later, so even if they had had the concept, they couldn't measure it.
The bigger problem is that the exact coordinates of the Great Pyramid of Giza are 29.979167N, 31.134167E and the speed of light in a vacuum is 299792458m/s. So it's close, but it's out by about 8 metres. (And why didn't they put it about 28km further east, at 31.415926E ? That might have been weirdly convincing of the existence of time travel.)

Which brings me to the point of this post. Here are some important things in the world that have either their latitude or longitude (measured in degrees) be a number that's close to a multiple of a 10th power of the speed of light. All of these are closer to this ideal than the Great Pyramid of Giza.

  • Port Neches Elementary School in Texas, Latitude=29.97925, Longitude=-93.95905, according to Geonames. Presumably this is the address of the entrance, if you just move 47cm south (18.5 inches), you'll be spot on. Fun fact for Port Neches Elementary School students: if you travel east or west (and don't deviate even a little bit), you'll eventually hit the Great Pyramid of Giza. Google maps puts Port Neches Elementary School well away from this, and says that the Subway opposite the Neches Federal Credit Union / Magnolia Church is the speed-of-light latitude.
  • Crowne Plaza Astor New Orleans Latitude=29.97922, Longitude=-90.1137. If you are the events manager for the Crowne Plaza Astor, I hope you have locked up the lucrative market for Physics Conferences at important latitudes. Just 2.87 metres north and you're on the light speed location. (Google Maps is again out-of-sync with geonames, and suggests the pedestrian crossing on North Tonti Street where it meets Aubry Street; it also suggests the Jewish Cemetry near the Hurrican Katrina Memorial... and the Mortuary Haunted House.) I don't know whether to believe Google maps or Geonames. I was on the Google Maps SRE team briefly in 2006--2007, but I spent the majority of my time on the maps team nowhere near any other maps team members, so I don't have an insider opinion on Google Maps accuracy.
  • The Omnipotent Missionary Baptist Church. This seemed to have disappeared from Google Maps, if it was ever there, which I guess is a thing you can do if you are an Omnipotent Missionary. (But what do Omnipotent Missionaries evangelise about? Themselves?) It was at Latitude=29.9792, Longitude=-90.03.
  • I tried to find a few places in China, but between inaccurate maps and other problems it's hard to be sure. The Wuhan Institute for Virology is just a little bit too far north to be on the light-speed latitude.
  • According to Google Maps, the Benedictine Monastery of Toumliline is very close. But Wikipedia puts it several degrees of latitude in a different direction. For Moroccoa, Geonames suggests the town of of Aguerd Issegane, which seems like cheating because it's a town... but it's surprisingly small.
  • Geonames also suggests New Orleans' East Bank Sewage Treatment Plant.
But why latitude? Why not longitude? (Well, we couldn't calculate longitude accurately until well after Galileo, because we had no accurate time keeping mechanism that could survive a journey. For a long time, the only option was to observe when eclipses of Jupiter's moons happened; compare that to an almanac of when they were supposed to happen, then look at the angle of the sun or a fixed star and work out what longitude you were at. Way beyond what any ancient Egyptian could have done.)

So for longitude 29.97925E:
  • It's quite close to the Chernobyl nuclear power plant (51°23′21″N 30°05′58″E) -- but the powerplant is about 8km too far east. 
  • Suri Suri Dam in Zimbabwe is very close to the light-speed longitude (-18.08597,29.97944)
  • Playing around with Google Maps, I found that the southern most shed of the University of Alexandria's Faculty of Agriculture Poultry Farm was is on the speed-of-light longitude.

But why latitude 29.97925? Surely 2.997925 would be better? And here we hit the jackpot:
  • Taman LEP 7 Stop (which I think is a bus stop in Kuala Lumpur). Latitude=2.99793, and longitude=101.64858. The KL bus transit authority has encoded the speed of light in the bus stop!

Here's how I did it. Download the Geonames database, unzip it, create a postgresql database:



 createdb geonames

Then in the postgresql session:

CREATE TABLE geoname (

        geonameid int,

        name varchar(200),

        asciiname varchar(200),

        alternatenames varchar,

        latitude float,

        longitude float,

        fclass char(1),

        fcode varchar(10),

        country varchar(2),

        cc2 varchar(60),

        admin1 varchar(20),

        admin2 varchar(80),

        admin3 varchar(20),

        admin4 varchar(20),

        population bigint,

        elevation int,

        gtopo30 int,

        timezone varchar(40),

        moddate date


\copy  geoname (geonameid,name,asciiname,alternatenames,latitude,longitude,fclass,fcode,country,cc2, admin1,admin2,admin3,admin4,population,elevation,gtopo30,timezone,moddate) from 'allCountries.txt'  null as '';

create index on geoname(latitude);

create index on geoname(longitude);

select * from geoname where latitude < 29.980 and latitude > 29.979 order by abs(latitude - 29.9792458);

And then likewise for different latitudes and longitudes.


  • Gungele is at Pi latitude. Latitude=3.14159, Longitude=28.14137. (So close to being 10 times e!)
  • VilledonnĂ© is at e longitude (to 6 decimal places) Latitude=47.27323, Longitude=2.71828
  • A beach in Tiomann Island (Pasir Gerengganin Malaysia is at e latitude. Latitude=2.718,  longitude=104.1724 

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