Mini

Torus Universe: A Quantum Jackpot for the Big Bang

Original: "Inflation and topology from the no-boundary state"
· Victor Godet
arXiv:2605.05317v2 · 2026-05-06 · CC BY · ⏱ 1 min · HEP Theory General Relativity
The Hartle-Hawking wave function on a three-dimensional torus turns exponentially suppressed inflation into an almost guaranteed scenario, predicting over 250 e-folds.
Links in the knowledge graph 1

Topology changes the rules. Before, quantum birth spawned microscopic universes, but the T³ torus almost guarantees prolonged inflation: an average of 250 e-folds, 80% chance for >60. The secret is the group SL(3,Z), which converts exponential suppression into a gentle power law. And behind the scenes, the Riemann zeta function—whose zeros tune the orchestra of the cosmos.

🎯 In string theory, the modular group SL(2,Z) rules; here its three-dimensional cousin SL(3,Z) makes its debut. And the physical answer is expressed through the zeros of the Riemann zeta function—as if the distribution of galaxies is dictated by prime numbers. The nearest zero: ~14.1347i—and numbers like these govern quantum corrections to the shape of the Universe.

🎬 In the story 'The Wall of Darkness' (1949), Arthur C. Clarke sent his heroes on a journey through a torus universe, where the edge of the world loops back on itself. Today, we test this geometry not with our feet but by gazing at the sky—through the subtle ripples of the cosmic microwave background.

\langle \Psi | \Psi \rangle \propto \frac{M_P^4}{V(\phi_*)}
The norm of the Hartle-Hawking wave function for T³—the probability of starting inflation is inversely proportional to the potential, not exponentially small.
P(N) = 2\varepsilon_V e^{-2\varepsilon_V N}
Exponential distribution of the number of e-folds with a mean N ≈ 1/(2ε_V) ≈ 250.
Scientists
Alan GuthAndrei LindeGeorges LemaîtreJames PeeblesAdam RiessBrian Schmidt
Tags
big bang expansion of the universe cosmic microwave background spacetime curvature gravity Quantum Field numerical simulation inflation
Laws
Friedmann equationsHubble's lawNoether's theoremEinstein field equationsPlanck's lawequivalence principle
Original: arXiv:2605.05317v2 · CC BY · bridge42worlds