The claim: The Quran computes the value of the speed of light with unbelievable accuracy.
Sources: "Speed of Light"; "Quran and The Speed of Light?" (video)
Best rebuttal online: At Islam Watch.
My two cents:
This is a clear case of cherry picking numbers to sound plausible. They had to use some incredibly tortured logic to drag the number "12,000 lunar orbits" out of a fairly generic verse which, after all, makes no reference whatsoever to moons or distances or even the number 12. They are taking something vague and trying to make it specific, which after all is what all apologists do when they want to make a prophecy out of something that isn't. If it hadn't been the moon, they could have tried "1000 centuries of walking" or "1000 rotations of the earth" or "1000 earth orbits" -- ANYTHING which gets them within the right order of magnitude to something specific.
Then that's not enough to get them all that close, so they screw around with the numbers more. For instance, you'll notice they use some extremely fuzzy math to claim that there are 86170 seconds in a day. There aren't 86,170 seconds in a day, there are 86,400. If there were as much as 230 seconds difference every day, then we'd have a leap year every year.
They do all kinds of stupid math tricks just to line up some number with a lunar cycle to match a verse that doesn't even say anything about lunar orbits, and then they claim that the Quran predicts the speed of light. Okay. If that's the case, then why didn't the ancient Muslims know what the speed of light was? Why is it never referenced anywhere? Why isn't it calculated? Why, in fact, did no one think to calculate the speed of light from the Quran until long after
I'll tell you why, because it's nonsense. It's applying known scientific facts, discovered by westerners, and giving credit to their holy book by retrofitting nonsensical numerology with cherry picked frames of reference.
How did the authors of the Quran have such fantastic futuristic knowledge, Muslims ask? It's really simple when you recognize a few facts. The Quran is an ancient book written by people who had no knowledge of modern science, and in fact reads this way. A contemporary person who knows some science can make passages of the Quran superficially resemble scientific insights by manipulating verses that have nothing to do with science and trying to pigeonhole them into something resembling contemporary knowledge.
You could, if you were so inclined, do exactly the same thing with "The Canterbury Tales," "The Epic of Gilgamesh," or Lewis Carrol's "Jabberwocky."