The actual shape of the universe is like a giant cosmic fingerprint that's forcing space to stretch out unevenly.
arXiv · March 16, 2026 · 2603.12319
Why it matters
Standard cosmology assumes the universe is the same in every direction and expands uniformly. This paper shows that if the universe has a finite, non-trivial 'shape' (topology), quantum fluctuations from that shape will inevitably push the expansion lopsided, breaking the perfect symmetry we expect.
From the abstract
A finite, scheme-independent Casimir contribution to the stress-energy tensor arises naturally for quantum fields in universes with non-trivial spatial topology. We compute this Casimir stress-energy tensor contribution for a conformally coupled scalar field and for a minimally coupled scalar field. We show that, for the conformally coupled case, the backreaction of this contribution to the Einstein equations during an expanding de Sitter phase drives anisotropic expansion even when the Universe