After Relativity: When Spacetime Becomes Reality: 3 Cosmology and the View from Nowhere

There is a familiar escalation in the physicist’s story.

Relativity tells us there is no preferred present. Cosmology then appears to tell us what really exists: the universe as a whole, its origin, its fate, its total inventory of matter, energy, and spacetime. What was earlier denied — a privileged standpoint — seems to return, quietly reinstated at a higher level.

This post is about that reinstatement. Not as an error in physics, but as a category mistake in how cosmological explanation is often heard — and sometimes encouraged to be heard.

From Relativity to the Universe

Relativity is, at heart, a discipline of restraint. It tells us that descriptions of motion, duration, simultaneity, and geometry must be invariant under well‑specified transformations. No inertial frame gets to declare itself the one that things are really happening in.

Cosmology inherits this discipline — but it also tempts us to forget it.

When physicists speak of the universe expanding, of spacetime curvature evolving, of the early universe being hot and dense, they are not suddenly stepping outside all frames. They are working within a very particular modelling move: treating the universe as approximately homogeneous and isotropic at large scales, and then selecting a class of coordinate systems adapted to that assumption.

This is an extraordinarily successful construal. But it is still a construal.

The Cosmological Frame

Cosmological models typically rely on a preferred foliation: a slicing of spacetime into spacelike hypersurfaces labelled by a cosmic time parameter. Relative to this slicing, one can say what is happening “at the same time” across vast distances, track average densities, and define a global expansion rate.

Nothing in the mathematics forbids this.

What is forbidden — by the very spirit of relativity — is mistaking this modelling convenience for an ontological privilege.

Cosmic time is not the time. It is a time defined relative to a particular symmetry assumption and a particular class of observers (those at rest with respect to the cosmic microwave background, for example). It is useful, powerful, and deeply informative. But it is not a view from nowhere.

The Quiet Return of Absolutes

Here is the slide that matters.

Once we start speaking of the age of the universe, the size of the universe, or the state of the universe at a given time, it becomes very easy to hear these as statements about reality as such, rather than statements internal to a modelling framework with explicit constraints.

The language invites metaphysical inflation.

The universe begins to look like an object with a biography — a thing that came into existence, developed, and may end — rather than a theoretical object constituted by the relations we use to make sense of observations.

Nothing in cosmology requires this inflation. But much popular and semi‑popular discourse quietly depends on it.

Explanation Without Escape

Cosmology explains patterns in astronomical data by embedding them in a highly constrained theoretical structure. It tells us why distant galaxies exhibit redshift patterns, why background radiation has the spectrum it does, why large‑scale structure has the correlations it has.

What it does not do is step outside all description to tell us why spacetime itself exists, or why there is a universe rather than nothing.

Those questions may be meaningful in other registers. They are not answered by cosmology, despite how easily cosmological success can make it feel otherwise.

The Moral of the View

The lesson here mirrors the earlier posts.

Relativity denied us a privileged present. Cosmology does not give it back — unless we let a modelling convenience masquerade as an ontological standpoint.

There is no cosmic balcony from which the universe can be surveyed whole. There are only constrained perspectives, carefully chosen symmetries, and extraordinarily disciplined ways of seeing.

That discipline is the achievement. The temptation to transcend it is the recurring mistake.

In the next post, we will look at what happens when this temptation crystallises into origin stories — the Big Bang as beginning, explanation, and closure — and why that final step is neither required nor earned by the physics itself.