Could a Ship Use Expansion of Space to “Travel” Faster Than Light?

Written by OC Wanderer, author of Destiny Among the Stars, a LitRPG sci-fi series set in the real stellar neighborhood. Published September 4, 2026.

Most of the faster-than-light speeds on our list give a starship designer little to work with: a pattern, a projection or a correlation cannot carry a crew. The growth of distance itself is the one that makes me want to keep looking. If space can stretch between galaxies, could an engineer shape it around a ship?

Suppose a crew leaves the Solar System while the space ahead of them shrinks and the space behind them grows, carrying them toward Alpha Centauri while they sit at rest inside their hull. I wonder whether general relativity allows a ship to do that on purpose. Miguel Alcubierre's 1994 geometry says yes on paper, and the audacity of that idea is worth exploring: a crew could cross the stars by changing the space around them.

Distances grow faster than light because space itself stretches

Picture two ants standing still on a balloon that is being blown up. Neither ant takes a step, and the gap between them still widens. Now give that balloon the scale of the universe. Hubble's law says the farther away a galaxy is, the faster the gap to it grows, in direct proportion to the distance. At about 14.5 billion light-years the gap grows at the speed of light, and at any greater distance it grows faster.¹ The galaxies need not race through their neighborhoods for the distance between them to outgrow light's pace.

The wonderfully strange part is that we can see galaxies receding faster than light. Tamara Davis and Charles Lineweaver explain that hundreds have been observed in the standard model of cosmology.² Each sits at rest in its own neighborhood, where relativity's local speed limit holds, and no observer anywhere overtakes a beam of light. Their light can reach us because the growing universe eventually lets some of those photons gain on the gap. The region that sent us the oldest light there is, the cosmic microwave background, is now moving away from us at 3.2 times light speed.³ Looking at the sky already means looking across distances whose growth outruns light.

Relativity's speed limit governs how fast something moves past its neighbors through space. The gap between two galaxies grows because the space between them gets larger, and the limit does not apply to that.

Alcubierre's geometry builds a local version, with the ship at rest inside

What if we could bring that change of distance down to the scale of a hull? Alcubierre paired expansion with contraction in a small region: space growing behind the ship and shrinking in front of it, carrying the ship away from Earth and toward a distant star.⁴ Between the two lies a bubble of ordinary, undistorted space, and the ship sits in the middle of it. I love the reversal of the usual propulsion problem. Instead of asking how hard an engine must push a crew, we get to ask what happens if the crew's surroundings do the traveling.

For a storyteller, the crew's clocks are as enticing as the speed. Alcubierre's equations put the ship in free fall, with no felt acceleration, and its clock keeps the same time as clocks in the undistorted space outside.⁵ In the time dilation we worked out earlier, a forty-year trip aboard meant roughly a thousand years passing on Earth; here the crew's clock matches home's. Imagine reaching another star and still sharing a calendar with the people you left behind. An observer outside a faster-than-light bubble sees it cover a light-year in less than a year, while the ship never outruns the light next to it: the distortion carries that light along too.

In Destiny Among the Stars, Director Almeida says the drive "creates a pocket of reality that moves with the ship, anchoring it while the surrounding universe flows" (Book 1, Chapter 12). Danny describes the drive as folding space around them (Book 1, Chapter 21).

A ship needs a chosen course, so the bubble has to be built

I would happily let the universe supply the propulsion if it could take us somewhere we chose. Cosmic expansion, though, offers no heading for a pilot to select: it stretches space in every direction, and the rate grows with distance. At Alpha Centauri's distance of 4.37 light-years, Hubble's law would give about 9 centimeters per second, but gravity holds our neighborhood of the galaxy together, so Alpha Centauri takes no part in the expansion at all.⁶ Even that hypothetical nine centimeters per second would be a disappointing entry on a starship's performance sheet.

Alcubierre's geometry lets a designer put a chosen path into the equations, along with the bubble's size and wall thickness; spacetime becomes essentially flat away from the bubble.⁷ That is a tantalizing set of choices to have on paper. A real crew would still need hardware that could produce the chosen geometry and control it.

In the book, the Vanguard drive cannot skip the Triumph between the normal folds of spacetime until it establishes a Reality Anchor Field, Danny explains. The calibrations the crew runs are about setting that field's size and holding it there (Book 1, Chapter 15).

So could a ship use the expansion of space?

On paper, yes: Alcubierre's bubble gives a ship a local version of expanding and contracting space, with the crew at rest inside. The universe's expansion cannot take us on a chosen course, so someone would have to build the bubble. I find the possibility thrilling because it leaves room for a voyage and a homecoming on the same human calendar. Now comes the harder question: what would that crew need to make the geometry real, and who could steer it? Why can't we actually build the Alcubierre drive?

Endnotes

1. Author calculation: the distance at which recession reaches the speed of light is c/H₀. With H₀ = 67.4 km/s per megaparsec from Planck Collaboration, “Planck 2018 results. VI. Cosmological parameters,” Astronomy & Astrophysics 641 (2020), A6, arXiv, c/H₀ = 299,792 / 67.4 = 4,448 megaparsecs, or about 14.5 billion light-years. Tamara M. Davis and Charles H. Lineweaver call this distance the Hubble sphere. ↩

2. Tamara M. Davis and Charles H. Lineweaver, “Expanding Confusion: Common Misconceptions of Cosmological Horizons and the Superluminal Expansion of the Universe,” Publications of the Astronomical Society of Australia 21 (2004), 97–109, arXiv, section 3.3: for (Ω_M, Ω_Λ) = (0.3, 0.7), all galaxies beyond a redshift of z = 1.46 (a redshift is the stretching of a galaxy’s light toward longer, redder wavelengths, which grows with distance) are receding faster than light, and hundreds of galaxies with z > 1.46 have been observed. Section 3.1: such galaxies are at rest locally, with zero peculiar velocity. ↩

3. Davis and Lineweaver (2004), section 3.3: the points that emitted the cosmic microwave background, at redshift about 1100, recede at 3.2c today and receded at 58.1c at the time of emission, for (Ω_M, Ω_Λ) = (0.3, 0.7). The discussion of Figure 1 explains why the light reaches us: the Hubble sphere grows with time, so some photons that start in the superluminally receding region later find themselves in the subluminal one. ↩

4. Miguel Alcubierre, “The Warp Drive: Hyper-Fast Travel within General Relativity,” Classical and Quantum Gravity 11 (1994), L73–L77, DOI, arXiv. The abstract describes “a purely local expansion of spacetime behind the spaceship and an opposite contraction in front of it,” and the text says the spaceship is “pushed away from the Earth and pulled towards a distant star by spacetime itself.” ↩

5. Alcubierre (1994), equation 13 and the text after it: the ship’s proper time equals coordinate time, so it “suffers no time dilation as it moves,” it moves on a geodesic with zero proper acceleration, tidal forces near the ship are very small when the wall parameter σ is large and the bubble radius R exceeds the ship’s size (they can be very large near the wall), and “light itself is also being pushed by the distortion of spacetime,” so the ship stays inside its local light cone. ↩

6. Author calculation: 4.37 light-years is 1.34 parsecs, or 1.34 × 10⁻⁶ megaparsecs, and 67.4 km/s per megaparsec × 1.34 × 10⁻⁶ megaparsecs = 9.0 × 10⁻⁵ km/s, about 9 cm/s (H₀ from note 1). Gravitationally bound systems such as the Milky Way and its neighbors hold together and take no part in the expansion (a standard result; Davis and Lineweaver, section 2, speak of objects “not gravitationally bound to us”). ↩

7. Alcubierre (1994), equations 3 and 6: the ship’s trajectory x_s(t) is an arbitrary function of time, and the shape function f depends on the chosen parameters R and σ; the shift vanishes far from the ship, so spacetime is essentially flat everywhere except within a region of radius of order R around it. ↩