I'm working on a book about Revelation in the Bible. When I came to this verse, my sci-fi writer brain came online.

The city is laid out as a square, and its length is as great as the width; and he measured the city with the rod, fifteen hundred miles; its length and width and height are equal. (Revelation 21:16)

The New Jerusalem is described as a massive city, with its length, width, and height each measuring 1,500 miles. To put this into perspective, this is larger than most countries and covers an area comparable to a majority of the United States. It is unlike anything ever seen in human history—no city has ever come close to one side of this structure, not to mention being stacked 1,500 miles high. 

The space afforded in New Jerusalem will be about 3.4 billion cubic miles. We don’t know the population that will live within the Holy City, but even at an average rural population density, the New Jerusalem could comfortably house more than the entire human population that has ever lived on Earth, with room to spare, and could be filled with hundreds of trillions of people at a more modern, urban population density. 

At the immense scale of 1,500 miles per side, if its construction were attempted under the known laws of physics, the New Jerusalem could not maintain a cubic shape using any materials known to science. The sheer mass would generate gravitational forces comparable to a small moon, inevitably compelling the structure toward spherical equilibrium as its outer portions collapse inward. Without supernatural factors, the laws of gravitation would invariably transform any attempt at such a massive cube into a spheroid if it were in space and crush it under its own weight if it were on a larger planet.

Even more astounding, the city’s height also measures 1,500 miles. For reference, Earth’s atmosphere extends approximately 62 miles above the surface to the Kármán line, often considered the boundary of space, with the thermosphere extending up to 372 miles. The New Jerusalem’s height surpasses even the exosphere’s lower boundary, venturing well into what we classify as outer space. 

From a physical perspective, if this city were a solid mass placed on Earth, it would disrupt the planet’s tides and orbit, especially if constructed with dense materials like gold. Its immense weight would destabilize the Earth’s gravitational balance, potentially pulling the moon out of orbit. Clearly, this city exists within a completely different system—a new creation.

The city is also described as coming down out of heaven and descending. Considering its mass, if it were coming down at typical orbital velocity, the retro-thrust required to halt such a mass, to prevent it from colliding with a planet the size of Earth, would require more energy than could be produced by a nuclear arsenal a trillion times greater than the one the human race has so far manufactured. Just slowing it down would be enough energy to destroy the planet. 

Maybe the point is that this city is impossible without God’s divine intervention. Its shape, size, materials, location, and structure shouldn’t work. If the laws of physics are still the same in the New Creation, it will be a continual reminder that God is powerful and presently working to hold together His creation, including the New Jerusalem. The mere shape, size, and structure of the city are miraculous. It’s awesome to think that we will live in a miracle city forever.