S23
Expansion of the heavens
"And the heaven We constructed with strength, and indeed, We are [its] expander" (51:47): the verse speaks of a sky built with power and made wide.
وَٱلسَّمَآءَ بَنَيْنَٰهَا بِأَيْي۟دٍ وَإِنَّا لَمُوسِعُونَ٤٧
Transliteration: wal-samāa banaynāhā bi-aydin wa-innā lamūsiʿūna
And the heaven We constructed with strength, and indeed, We are [its] expander.
Translation: Saheeh International
Key words
Bi-ayd: "with strength", power (not "hands"). Mūsiʿūn: "expander" — from wasiʿa, to be wide; it can mean "We make wide", "We are making wide", or "We have vast power/capacity".
Classical tafsir
Ibn Kathir. "With strength" is explained by Ibn ʿAbbas, Mujahid, Qatada and al-Thawri; la-mūsiʿūn means: "We made it vast and We brought its roof higher without pillars to support it" (as read for run 9).
Other readings. Al-Tabari has not yet been consulted.
What they did not say. In Ibn Kathir's reading, the sky was made vast; he does not describe it as growing over time.
How it works
Expansion rate (km/s per megaparsec)
Text version
In 1929 Hubble presented the first observational evidence that the universe is expanding in all directions. The expansion rate, the Hubble constant, comes out at 67–68 km/s per megaparsec from the early universe but 73–74 from the nearby universe: the "Hubble tension". As space stretches, every point sees every other point move away, and farther ones faster. The classical commentators did not read 51:47 this way.
Each point is tied to mūsiʿūn.
- The universe is expanding. Established In 1929 Edwin Hubble presented the first observational evidence that the universe is expanding in all directions (Harper, Sky at Night).
- How fast. Established (with an open problem) The expansion rate, the Hubble constant, comes out at 67–68 km/s per megaparsec from the early universe (the Planck mission's measurements of the cosmic microwave background) but 73–74 from the nearby universe (Hubble Space Telescope and Gaia). This disagreement is the "Hubble tension" (Harper). A megaparsec is almost 3.3 million light-years.
Points of awe
Hubble found that "the Universe is expanding in all directions" (Harper).
Reflection
"And the heaven We constructed with strength" (51:47). The verse begins with power. The sky, so vast and high, was built — and built with strength. Then: "and indeed, We are [its] expander".
Ibn Kathir read this as God having made the sky wide and raised it "without pillars to support it". For him, the point was the size and order of what God had made, and His power over it.
Modern astronomy has found something the first listeners could not see: the universe is not only vast, it is growing. The distances between galaxies are increasing, and we are still arguing about exactly how fast. The verse's word mūsiʿūn can be read in harmony with that, and a reader may notice it.
But the verse's own direction is clear: it points to the One who built, and who widens. The verses that follow move from the sky to the earth spread out, and then to the pairs in all things, "perhaps you will remember" (51:49). The sky is a sign that should send us back to God, not only forward to a measurement.
Questions readers ask next
Does 51:47 say the universe is expanding?
The word can be read that way, but Ibn Kathir read it as God having made the sky vast.
What is the Hubble tension?
The disagreement between the expansion rate measured from the early universe (about 67–68 km/s/Mpc) and from nearby stars (about 73–74) (Harper).
What does bi-ayd mean?
"With strength", according to Ibn ʿAbbas, Mujahid, Qatada and al-Thawri (Ibn Kathir) — not "hands".
Sources
- Saheeh International — 51:47.
- Ibn Kathir, Tafsir (abridged English), on 51:47, https://surahquran.com/tafsir-english-aya-47-sora-51.html (as read for run 9).
- Caroline Harper, "Hubble tension explained", BBC Sky at Night Magazine (26 July 2024), https://www.skyatnightmagazine.com/space-science/hubble-tension.
- CERN Courier, "The Hubble tension"
- Di Valentino et al., "Cosmological tensions in the era of precision cosmology" (arXiv 2025)
- Al-Ṭabarī and Ibn Kathīr on 51:47
- Nidhal Guessoum, Islam's Quantum Question (I.B. Tauris), on reading cosmology into verses