In Surah Al-Hajj (22:47), the Quran declares: "And indeed, a day with your Lord is like a thousand years of which you count" (وَإِنَّ يَوْمًا عِندَ رَبِّكَ كَأَلْفِ سَنَةٍ مِّمَّا تَعُدُّونَ). This affirmation, which evokes a dilation of time, was long considered metaphorical. Modern physics has revealed that time is indeed relative and can dilate according to speed and gravity.
The Quran also mentions this relativity in other verses: "He arranges [each] matter from the heaven to the earth; then it will ascend to Him in a Day, the extent of which is a thousand years of those which you count" (32:5) and "The angels and the Spirit will ascend to Him during a Day the extent of which is fifty thousand years" (70:4).
The historical context
In the 7th century, time was considered absolute and uniform, a conception inherited from Aristotle that would prevail until Newton. No one imagined that time could flow differently depending on the frame of reference.
This conception of absolute time dominated physics for centuries. Isaac Newton wrote in 1687: "Absolute, true and mathematical time, of itself, and from its own nature, flows equably without relation to anything external."
The theory of special relativity (1905)
In 1905, Albert Einstein published his theory of special relativity, which overturned our understanding of time. Its two fundamental postulates are:
- The laws of physics are the same in all inertial frames of reference.
- The speed of light in a vacuum is constant and independent of the motion of the source.
From these postulates follows a surprising consequence: time is not absolute but relative. Two observers in relative motion measure different durations for the same event. This phenomenon, called time dilation, has been confirmed experimentally many times.
The formula for time dilation is: Δt' = Δt / √(1 - v²/c²), where v is the relative velocity and c the speed of light. The closer the speed approaches the speed of light, the slower time passes for the moving observer.
The theory of general relativity (1915)
In 1915, Einstein generalized his theory to include gravity. General relativity shows that gravity deforms space-time: the more intense the gravitational field, the slower time flows. This phenomenon, called gravitational time dilation, has been confirmed by many experiments.
For example, atomic clocks located at sea level (in a more intense gravitational field) run slightly slower than those at altitude. The GPS system must constantly correct this effect to provide accurate positions.
Experimental confirmations
Time dilation has been confirmed by many experiments:
- 1938 : Ives and Stilwell confirm time dilation for rapidly moving particles.
- 1971 : Hafele and Keating fly atomic clocks around the world in airplanes; they lag in accordance with the predictions of relativity.
- 1977 : Cosmic muons, unstable particles created in the upper atmosphere, reach the Earth's surface even though their lifetime at slow speed would not allow it — direct proof of time dilation.
- Since the 1990s : The GPS system corrects daily for the effects of special and general relativity.
Time in the Quran
The Quran mentions the relativity of time several times, with different scales:
- "A day is like a thousand years" (22:47, 32:5) : a dilation by a factor of 365,000.
- "A day is like fifty thousand years" (70:4) : a dilation by a factor of 18,250,000.
- The Day of Judgment : "On the Day they see that which they are promised, it will be as though they had not remained [in the world] except an hour of a day" (46:35).
- The People of the Cave : "And they remained in their cave for three hundred years and increased by nine" (18:25) — a possible reference to the difference between the solar calendar (300 years) and the lunar calendar (309 years).
These verses show that time is not uniform and that its perception depends on the frame of reference, an idea that modern physics has confirmed.
The subjective perception of time
Beyond physics, psychology has also confirmed that the perception of time is subjective. Time seems to pass faster with age, and intense or traumatic moments seem to stretch. The Quran mentions this subjective perception in several verses: "On the Day they see it, [it will be] as though they had not remained [in the world] except for an evening or a morning" (79:46).
Detractors' arguments
This convergence, although striking, calls for several reservations that should be known in order to preempt criticism:
- A primarily eschatological verse. The context of 22:47 is that of deferred punishment: the disbelievers hasten the punishment, and the answer reminds them that a day with Allah is like a thousand years of their count. Some exegetes read in it above all an affirmation of divine patience and of the relativity of human time before God, not a physical equation.
- A retrospective reading. The link with Einstein's relativity only appears after 1905; one may object that this is a re-reading of the text in the light of a later discovery, not information the text itself conveyed.
- Non-comparable orders of magnitude. The Quranic durations (a thousand years, fifty thousand years) are not physical measurements of time dilation: they describe neither a moving frame of reference nor a gravitational field, and therefore cannot be equated with Einstein's formula.
- For the believer. These objections diminish nothing: they merely recall that the verse speaks first of Allah's power over time. The believer recognises in it that time, being created, is not absolute — which 20th-century physics did indeed discover.