Egyptian light speed

There's a claim I've now seen three times on social media stating that the ancient Egyptians knew the speed of light.

This is pretty outlandish right from the get-go, as there is no evidence the Egyptians had invented, or even had access to, any kind of advanced technology.  Plus, even with (relatively) modern technology, the first reasonably decent estimate of the speed of light wasn't made until 1676, when Danish astronomer Olaus Roemer used the difference in the timing of the eclipses of the moons of Jupiter when the Earth was moving toward them as compared to when the Earth was moving away from them, and came up with an estimate of 225,300,000 meters per second -- not too shabby given the limited technology of the time (the actual answer is just shy of 300,000,000 meters per second).

But there's something about those ancient Egyptians, isn't there?  There have been "secrets of the Pyramids" claims around for years, mostly of the form that if you take the area of the base of the Pyramid of Khufu in square furlongs and divide it by the height in smoots, and multiply times four, and add King Solomon's shoe size in inches, you get the mass of the Earth in troy ounces.

Okay, I made all that up, because when I read stuff about the "secrets of the Pyramids" it makes me want to take Ockham's razor and slit my wrists with it.  But I was forced to look at the topic at least a little bit when the aforementioned post about the speed of light started popping up on social media, especially when a loyal reader of Skeptophilia said, "You have got to deal with this."

The gist is that the speed of light in meters per second (299,792,458) is the same sequence of numbers as the latitude of the Pyramid of Khufu (29.9792458 degrees north).  Which, if true, is actually a little weird.  But let's look at it a tad closer, shall we?

[Image licensed under the Creative Commons Jerome Bon from Paris, France, Great Pyramid of Giza (2427530661), CC BY 2.0]

29.9792458 degrees of latitude is really specific.  One degree is approximately 111 kilometers, so getting a measurement of location down to seven decimal places is pretty impressive.  That last decimal place -- the ten-millionths place -- corresponds to a distance of 0.0111 meters, or a little over a centimeter.

So are they sure that last digit is an 8?  Measuring the position of the Great Pyramid to the nearest centimeter is a little dicey, given that the Great Pyramid is big (thus the name).  Even if the claim is that they're measuring the position of the top -- which is unclear -- the location of the top has some wiggle room, as it doesn't come to a perfect point.

But if you're just saying "somewhere on the Great Pyramid," there's a lot of wiggle room.  The base of the Pyramid of Khufu is about 230 meters on an edge, so that means that one-centimeter accuracy turns into "somewhere within 23,000 centimeters."

Not so impressive, really.

There's a second problem, however, which is the units used in all the measurements in the claim.  The second wasn't adopted as a unit of time until the invention of the pendulum clock in 1656.  The meter as a unit of length wasn't proposed until 1668, and was not adopted until 1790.  (And some countries still don't use the metric system.  *glares at fellow Americans*)  So why would the ancient Egyptians have expressed the speed of light -- even assuming they could figure it out -- in meters per second, and not cubits per sidereal year, or whatever the fuck crazy units of measurement they used?

Oh, and while we're at it, the first person to slice a circle up into 360 degrees -- the basis, of course, of our system of latitude -- was Hipparchus, who lived in the second century B.C.E.  Which, not to put too fine a point on it, was two-thousand-odd years after the Great Pyramids were built.  So to sum it up: what we're being asked to believe is that the ancient Egyptians sited the Great Pyramid based upon a quantity they didn't know how to measure, expressed in terms of three units that hadn't been invented yet.

Makes perfect sense.

So as expected, this claim is pretty ridiculous, and not even vaguely plausible if you take it apart logically.  Not that there was any doubt of that.  In fact, this is only one of dozens of examples of pseudoscientific metrology, which is the general name for claims that the measurements of ancient structures have some relevance to scientific findings.  The bottom line is that the ancient Egyptians were cool people, and the pyramids they built are really impressive, but they weren't magical or advanced or (heaven help us) being assisted by aliens.

No matter what you may have learned from the historical documentary Stargate.

Oh, and for the record, I didn't invent the unit of "smoot" for length.  A smoot is 1.70 meters, which was the height of Harvard student Oliver R. Smoot, who in 1958 got drunk with his fraternity buddies, and as they were dragging the semi-conscious Smoot home, they decided to measure the length of Harvard Bridge in Smoot-heights.  It turned out to be 364.4 smoots long, plus or minus the length of Oliver R. Smoot's ear.

And considering they were drunk at the time, it's pretty impressive that they thought of including error bars in their measurement.  Better than the damn Egyptian-speed-of-light people, who couldn't even get their measurement to within plus or minus 230 meters.

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