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It appears to be popular to claim that the Qur'an predicted the speed of light before it was scientifically well understood. Although none of the sources state that outright, that is what they imply.

Example:

Moslems (Muslims) believe that angels … move at any speed … up to the speed of light. It is the angels who carry out God's orders. …

[Quran 32.5] (Allah) Rules the cosmic affair from the heavens to the Earth. Then this affair travels to Him a distance in one day, at a measure of one thousand years of what you count.

[P]eople back then measured the distances … by how much time they needed to walk.… [I]n this verse the Quran specifies 1000 years of what they counted (not what they walked). … Since this verse is referring to distance, then God is saying that angels travel in one day the same distance that the moon travels in 12000 lunar orbits. We discovered that in an inertial geocentric frame 12000 Lunar Orbits/Earth Day is equivalent to the speed of light.

Is this true?

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    Actually I think the math is wrong already. Talking about months of 27 days and years of 365 days, 1000 years don't have 12'000 months. I'll see if I get together enough material to make it an answer later.
    – drat
    Commented May 21, 2014 at 14:20
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    Did anyone make this calculation prior to modern estimates of the speed of light? If not, then this is just post-hoc numerology (i.e. they wanted something to be true, so they found the calculations that would make it seem to be true)
    – adam.r
    Commented May 22, 2014 at 13:53
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    The claims are wrongly stated, Many Muslims actually believe angels travel faster then light.
    – user11777
    Commented May 22, 2014 at 18:10
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    Circumference can also apply to an ellipse, so the number is fine. The Quran is wrong.
    – HDE 226868
    Commented Oct 16, 2014 at 1:55
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    For me, "one thousand years" seems like a random made-up number on paper.
    – Rápli András
    Commented Oct 17, 2014 at 17:58

3 Answers 3

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TL;DR : No, even if one chooses to interpret the excerpt of the Qur'an as such, the maths don't hold up

I am going to base this answer on your second source, as the calculation there is reduced to the minimum which makes it a lot easier to show its flaws. This is an answer on the mathematical aspect of the problem, not covering the interpretation of the quote.

In a simple calculation based on the real month, the moon travels 2152612.27 km around earth in compete round. This distance represents the length of the orbit that the moon takes while a complete round during one month.

Wrong. According to NASA, the circumference of the orbit of the moon around Earth is 2'413'402.16 km.

Now, how long is a month? A sidereal month is 27.21 days in solar days of 24 h (86'400). Note the definition of a day in the source, which is 86'164 this is also correct, but that's a sidereal day, meaning a day as measured in relation to the positions of the stars and not the sun.

So the distance per year is: 2152612.27 × 12 = 25831347 km

And in one thousand year is: 25831347 × 1000= 25831347000 km

There's another problem. One year doesn't have 12 months. The Islamic Calendar Year has 355 days. Considering a month of 27.21 days as mentioned above, 1000 years are equal to 13'019 months.

With this we can calculate the distance the moon travels in 1000 years, which is roughly 28'000'000'000 km.

The cosmic speed = 25831347000 ÷ 86164 = 299792 km\ second which is exactly the speed of the light.

Assuming this correspond to the distance light will travel in one day, we get a speed of 324'000 km/s which is more than the speed of light (roughly 300'000 km). Using the sidereal day won't help, as this will only make the value bigger.

Now in a lot of the calculations they use the synodic month instead (29.53 days). This will indeed decrease the number of months but this effect will be entirely canceled out as this leads to a proportional increase in the orbit circumference. (One cannot define the month with one definition of the orbit and then use another definition of the day to calculate the distance per day.)

In all three sources they come to the result either by mixing up different definitions of days, orbits and the like and omitting any explanation for it. Or by using overly complicated calculations to an easy problem to hide those errors in a lot of smart looking maths.

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    So the Quran's "prediction" is about 11% off. That's actually not bad at all, if you compare it e.g. with Eratosthenes' measurement of the circumference of the earth, which was 16% off, and also take into account that it's a prosaic text, where a writer might trade numerical accuracy for prosaic effect.
    – Saibot
    Commented May 22, 2014 at 12:19
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    True, but it still is in contradiction with the claims of the sources, which all get values which are incredibly close to it. You are of course right, if the text would say something very specific, such as "The angels travel the same distance the moon travels in a 10'000 years in a day", then this would be a very good estimation. But as it stands the text does not mention specifically the moon etc., so this is similar to someone trying to match current events to Nostradamus prophecies, it is always possible to find some numbers that give the result that one wants.
    – drat
    Commented May 22, 2014 at 12:40
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    Drat seems to have hit the point. I am not exactly sure why we care about the distance that that moon travels. But I disagree with how you interpret the results. It is pretty obvious that the 1000 needs to be interpreted as having one significant digit, that means that a result of 324'000 km/s, or indeed anything around that must also be considered as 3*10^5 km/s which within the bounds of our precision ~= the speed of light.
    – Jonathon
    Commented Oct 16, 2014 at 4:18
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    @JonathonWisnoski I talked about that in the second comment above. Yes, it is a reasonable estimate, but it is nothing like the crazily accurate numbers that were stated in the sources of the question. The rest is as I said in the above comment, the quote from the Quran is pretty generic, and it is rather a big jump from that quote. "What you count" could mean a lot other than "lunar orbital". With so much freedom of interpretation and such a low threshold for the precision, basically anything can be deducted from anything.
    – drat
    Commented Oct 16, 2014 at 12:10
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    When I run the numbers using 355 days in a year, 27.21 days per month, etc, my error margin comes in a 21%. (c = 670.6M mph, so 16.0948B miles per day.... lunar orbit 1.4996M miles per month, X 13,046 months in 1000 years = 19.565 B miles, 19.565/16.0948 = 1.21). I think 11% is pretty bad, 21% is even worse.
    – PoloHoleSet
    Commented Nov 21, 2017 at 17:10
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The most straight-up reading of the passage suggests nothing about a speed of travel through space. If anything, it seems to be another rendition of the common idea that "divine time" is much longer than "human time", so here, that what for God is one day, is for us, equal to 1,000 years. This idea is found in many religions including some that far predate Islam, such as Hinduism (e.g., if I remember right, in the Upanishads - I know for sure there is a hierarchy of "measures of bliss", but I also seem to remember an analogous hierarchy of time), where that it is talked of how the "days" or similar of certain gods are vastly longer in human terms than human days. The general idea of gods, after all, is that they are "far more/above/beyond" humans, so that their "time" is also, likewise, "bigger", fits into that.

In the end, the passage thus simply states a ratio between two times. What you need to talk speed is a ratio between a distance and a time. The insertion of a moon-derived distance represents an arbitrary choice by the interpreter to fill this missing component. This creates a fudge factor, which renders the argument nonpredictive.

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The question explicitly stated "geocentric frame", so all answers using "sidereal" measurements of months, days, and years for this question are pointless.

Using synodic measurements:

  • A "month" would be the time for a complete phase change, which averages to 29.53059 days. (Orbit of the Moon - Wikipedia)

  • The mean distance from the Moon to Earth is 385,000 km, giving an approximate mean orbital distance of 2.9919 million kilometres per month. (ibid)

  • A "year" is 365.24219 days. (Year - Wikipedia)

  • The speed of light is 299.792458 million m/s.

So:

  • The Moon orbits 2𝜋 × 385,000 km per month.
  • In 1 year, there are 365.24219 ÷ 29.53059 = 12.3682659 months.
  • In 1000 years, the moon will have orbited 1000 × 2𝜋 × 385,000 × 365.24219 ÷ 29.53059 km.

Compare:

  • The result of that last calculation is 29,919,161,089 km.
  • The speed of light is 299,792,458 m/s.

The ratio of those two numbers is 99.799578977, which is rather close to a 100% match.

(Even Ivory Soap is only 99 44/100% pure.)

With units, that ratio of 99.8 is 99,799 seconds.

I.e. the distance travelled by the Moon in 1000 years is as far as light will travel in 99,799 seconds (1.155 days).

But 15% error between 1.155 and 1 day is significant, much more than the ¼% error in the ratio calculation.

And even worse, as @PhilS points out, I mistakenly calculated the length of the Moon's orbit with respect to the stars, not to its phases, so the basic data is wrong too. (And ironically my mistake is exactly what I deemed "pointless" in the preamble to the answer.)

Even so, with only one unintentional mistake, it's still amazing that the resulting numbers, 29919 and 29979, should be so close.

And it provides a good example of why coincidences don't really prove anything.

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    Your numbers don't stack up . A mean orbital radius of 385,000 km translates to a distance of 2.419 million km per orbit and 2.617 million km between full moons, which is still around 15% off from the value you use (and you used the wrong one of $2\pi r$ which is the distance for a sidereal month, not a synodic one). Which is the same mistake pointed out by @drat in their answer. You are picking the wrong numbers inconsistently and plugging them in to get the answer you want.
    – PhillS
    Commented Oct 8, 2020 at 20:32
  • @PhillS, thanks. Once I saw the amazing similarity appear (the first 5 digits ended up identical during my initial lower precision calculations), I immediately stopped thinking, knowing that it was working out so amazingly well, and didn't bother to verify that my initial conditions were correct.
    – Ray Butterworth
    Commented Oct 8, 2020 at 21:36
  • "which is rather close to 100% correlation." That's not what "correlation" means.
    – Acccumulation
    Commented Oct 9, 2020 at 2:17
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    I still don‘t see where the orbit of the moon comes in. In the verse itself I don‘t see any mention of it. There are two ways to look at it: 1. If moon’s orbit comes in because then the result is speed of light than it’s all bogus because if you can choose your numbers freely you can get any result you wish to have. 2. If the moons orbit is actually mentioned, maybe indirectly, than the calculation, even if 30% off, is quite a remarkable result. Roemer’s first measurement was less accurate.
    – Hartmut Braun
    Commented Oct 10, 2020 at 7:27
  • The sidereal month is the time required for the moon to travel 2𝜋 × 385,000 km. Over the course of a synodic month, the moon travels about 390.695° or 2.17𝜋 × 385,000 km. But the Islamic year is by definition 12 synodic months, so 1000 of those is roughly 970 solar years.
    – phoog
    Commented Dec 2 at 0:18

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