Reconsidering Universal Expansion

For over a century, we’ve pictured the universe as a vast, stretching fabric—a cosmos expanding outward like ink dispersing in water. But what if we’ve been looking at it all wrong? What if the real story isn’t overall cosmic expansion, but contrast—a dynamic interplay between dense structures that contract and voids that expand? This shift in perspective could fundamentally reshape our understanding of dark energy, Hubble tension, and even the cosmic microwave background. Let’s dive into a new way of seeing the cosmos—not as a space that stretches, but as a universe that evolves through differentiation.

Spacetime Is Not a Stage

In standard cosmology, spacetime is often described as a dynamic stage — a flexible geometry that bends and stretches in response to mass-energy. Dense objects like stars and galaxies are seen as curving this stage, yet still treated as separate entities within it.

This article takes a different view: spacetime is not a container for mass-energy — it is mass-energy, expressed geometrically. A star doesn’t simply exist in spacetime; it is a dense knot of spacetime itself. Instead of imagining expansion occurring around objects, we should consider the universe as a shifting fabric in which some regions compress while others stretch — a dynamic often misinterpreted as uniform expansion.

According to General Relativity, spacetime curvature exists wherever mass-energy is present — both inside and outside of objects. The geometry of a galaxy, a star, or even a black hole is not separate from the fabric of the universe but a localized expression of it. Misunderstanding this — by picturing matter as sitting in spacetime rather than being spacetime — has led to conceptual conflicts in cosmology. Matter traveling along spacetime is spacetime traveling along itself.

By recognizing spacetime as the evolving, differentiated geometry of all mass-energy, we clarify the foundation — and open the door to new ways of interpreting cosmic expansion.

To illustrate, imagine pinching a balloon. The rest of the balloon’s surface expands as you pinch one area. If 20% of the balloon is pinched into a point, that point still contains 20% of the total surface area, while the other 80% stretches outward. It may appear that the entire balloon is expanding — if we ignore the pinch.

Another analogy is an old Euclidean grid drawn on paper. If you pinch the center, the grid lines near the pinch come closer, forming smaller, denser squares. These smaller squares still contain the same spacetime; they’re just compressed, more tightly packed with mass-energy. This is analogous to how spacetime behaves in and around massive objects. Curvature doesn’t imply less space inside; it means space is more compact — more structured. Interpreting these pinched regions as mere objects sitting in space overlooks the fact that they are space — curved, compressed, dynamic spacetime. From a distance, this pinch might go unnoticed, much like ignoring it on a balloon makes the rest appear uniformly expanding.

In standard cosmology, while spacetime curvature is acknowledged, global expansion is usually modeled separately from local curvature. Large-scale models treat the universe as smooth and homogeneous (using the FLRW metric), averaging out the highly curved, "pinched" local regions around stars and galaxies. These dense regions are considered perturbations and are often excluded from expansion narratives.

Consequently, much of spacetime curvature is excluded from the universal expansion story. The “pinched” regions — tightly bound with dense mass-energy — do not expand, yet they are spacetime too. Ignoring them can create the misleading impression that the entire universe uniformly stretches. A more complete view embraces spacetime geometry as continuous and evolving on all scales — from voids to stars — with expansion and contraction coexisting as parts of a complex, differentiated cosmic fabric.

Structural Contrast Redshift (SCR)

On the largest cosmic scales, the universe appears smooth and isotropic — the same in all directions — supporting the widely accepted view of uniform expansion. This large-scale stretching of spacetime is inferred through the consistent redshifts of distant galaxies. But zoom in, and the universe is anything but uniform.

Imagine a ball rolling toward you across a hilly, undulating surface — a landscape of valleys and peaks. Up close, you can see how each bump and dip affects the ball’s motion: speeding it up downhill, slowing it uphill. But from a distance, those features blur. The ball’s movement seems smoother — even slower — not because its speed changed, but because you're missing the detail beneath the motion.

Now imagine beams of light instead of rolling balls. Each photon crosses a “wavy” spacetime — not a smooth vacuum, but a patchwork of voids, filaments, gravitational wells, and energy gradients. With each structural feature encountered, a small shift in the photon’s wavelength accumulates. Over billions of years, these interactions add up, producing a redshift not from velocity, but from the cumulative contrast in the Ground.

From our perspective, light from more distant sources appears increasingly redshifted — not necessarily because those sources are racing away, but because their light has crossed a more intricate path. Like the rolling ball, the farther back the light started, the more terrain it has had to cross. What we observe is not a clear signal of velocity, but the integrated effect of cosmic structure.

In the standard model, this redshift is attributed to expanding space itself — a stretching of the universe over time. But what if it’s not uniform expansion, but cumulative structural contrast that builds as light travels through a dynamically textured universe?

In this alternative, what cosmology calls “cosmological redshift” is reinterpreted as Structural Contrast Redshift (SCR) — not the result of space expanding, but of photons interacting with the large-scale structure of the Ground.

Both interpretations produce the same redshift–distance pattern. Both make distant galaxies appear to recede faster. But in one model, space stretches evenly over time. In the other, the light’s journey is lengthened by the uneven terrain it must traverse. The illusion of acceleration might not reflect motion at all, but underlying structure.

To make this more intuitive, consider a real-world analogy:

The distance between Calgary and Vancouver is about 972 kilometers “as the crow flies.” If someone assumed you could drive that path directly at 100 km/h, they’d expect you to arrive in 9.72 hours.

But in reality, you drive a longer, more winding route — through foothills, over mountain passes, around valleys. By the time you reach Vancouver, your car’s odometer shows that you’ve traveled perhaps 1,150 km. You still drove at a steady 100 km/h, but the journey took longer due to the terrain — not because your speed changed.

Now imagine someone in Vancouver unaware of the topography. If you arrived later than 9.72 hours, they might wrongly conclude you were driving slower — or that the road stretched while you were en route — when in fact, it was the path itself that was more complex. Your odometer tells the truth: the longer time came from a longer route.

In the same way, photons travel at the constant speed $ c $, but through a universe filled with complex structure. The light’s path isn’t a straight shot through emptiness, but a winding course through the structural fabric of the cosmos. This extended journey doesn't mean the photon slowed down or lost energy — it means we misunderstood the nature of the terrain it crossed.

We interpret the redshift as a loss of energy or the result of expanding space. But in reality, it's an accumulated delay — the light followed a longer, more intricate route than we accounted for. Like a cosmic odometer, redshift reflects distance across structure, not expansion through emptiness.

This has significant implications: galaxies and supernovae that appear ancient in expansion-based models may, in fact, be much more recent. Their light simply had farther to travel through a complex universe — not because of recessional velocity, but because of structure.

On the largest observable scales, cumulative contrast smooths out into what appears like uniform expansion — or even accelerated expansion. As light travels through a cosmic web of expanding voids and contracting matter-rich regions, each variation adds a subtle redshift. Over vast distances, these shifts add up. From Earth, this accumulation mimics the signature of galaxies speeding away faster — the same signal standard cosmology attributes to dark energy.

But perhaps what we’re seeing is not the effect of a repulsive force stretching space, but the integrated imprint of a deeply structured cosmos. In this view, the redshift is not a stretch in space, but an echo of the path taken.

Importantly, this reinterpretation doesn’t alter the measure of cosmic time. Light still travels at $ c $, and lookback time remains valid. A galaxy seen as it was 12 billion years ago is still 12 billion light-years away by travel time. What changes is our understanding of the shape of its journey — and what that shape tells us about the evolution of the universe. It's not expansion that explains redshift, but structure.

Differentiated Spacetime Evolution

If spacetime evolves unevenly due to large-scale structure formation, we can describe the changing curvature with a dynamic relation:

$$\frac{dR(x,t)}{dt} = f\big(\rho(x,t),\ \nabla\rho(x,t),\ \Lambda_{\text{eff}}(x,t)\big)$$

R(x,t): Local Ricci curvature scalar
ρ(x,t): Local matter-energy density
∇ρ(x,t): Density gradient — capturing structural contrast
Λ_eff(x,t): An evolving vacuum energy term tied to structure

This captures how voids and overdensities push and pull the geometry of spacetime over time — not uniformly, but regionally.

Redshift as Integrated Structural Contrast

This reframes cosmic redshift as a record of cumulative structural contrast, rather than just global expansion velocity.

$$1 + z = \exp\left( \int_{\gamma} \alpha(x)\, ds \right)$$

γ: The light path (null geodesic) through cosmic structure
α(x): A local contrast-expansion rate term
ds: Proper distance element along the path

Redshift is not just a Doppler or stretching effect from uniform expansion, but a record of how much structural contrast light accumulates as it travels. The more 'uneven' the path, the greater the redshift — and this grows exponentially.

The Hubble Tension

The so-called “Hubble tension” refers to a mismatch between two measured values for what’s traditionally called the universe’s expansion rate:

~67 km/s/Mpc, derived from the cosmic microwave background (CMB), reflects conditions in the early, relatively smooth universe.
~73 km/s/Mpc, derived from observations of nearby supernovae and galaxies, reflects the late-time, highly structured universe.

But what if this tension isn’t about expansion at all?

This mismatch can be reinterpreted as a difference in the cosmic Differentiation Rate (DR) — the rate at which contrast between dense and underdense regions (structure) emerges and evolves across space and time.

In this view:

The late-universe value (~73) reflects redshift accumulation driven by increasing structural differentiation — not by expanding space, but by the deepening contrast between gravitationally bound regions and expanding voids. There is no true global "metric expansion." Instead, what’s observed is a cumulative redshift effect caused by photons traveling through increasingly differentiated structure. The resulting redshift is misread as a faster expansion, artificially inflating the inferred rate.
The early-universe value (~67) reflects a time before significant structure formed, when space was nearly uniform. It doesn’t capture present-day differentiation, which may be lower — perhaps closer to ~60 km/s/Mpc. In this model, the differentiation rate likely began high in the early universe, as structure formation surged, deepening contrasts between low- and high-density regions. Over billions of years, as large-scale structure stabilized, the rate would have gradually slowed, settling into a lower but still dynamic state. A present-day average global value around ~60 is speculative — not fixed, but likely lower than the CMB-derived 67, and certainly lower than the inflated late-time value of ~73.

So, the Hubble tension, from this perspective, reveals a need to rethink what redshift measures. It's not a precise expansion clock, but a differentiation signal, shaped by evolving structural contrast across time.