The early universe underwent cosmic inflation
A brief epoch of exponential expansion in the first fraction of a second explains the universe's flatness, homogeneity, and the origin of structure.
Evidence balance
Supporting
3- Cosmic inflationw65
Alan H. Guth · 1981 · Peer-reviewed
Inflation is the hypothesis; this is its proposal.
- Planck constraints on inflationw60
Planck Collaboration · 2020 · Peer-reviewed
Planck data are consistent with simple inflation.
- Singularity theoremsw30
Hawking & Ellis · 1973 · Book
Singularity theorems motivate seeking a pre-classical epoch like inflation.
Opposing
1- JWST observations of the early universew30
STScI / JWST · 2023 · Observation
JWST's early mature galaxies stress-test structure-formation timelines.
Assumptions
A suitable inflaton field exists
unjustified
Planck data favor inflation over alternatives
justified — Consistent with simple models.
Open questions within this hypothesis
- What is the inflaton?
- Will primordial gravitational waves be detected?
Falsification criteria
Detection of primordial B-mode polarization would strongly confirm it; a robust observation incompatible with inflationary predictions, or a better-fitting bounce model, would falsify it.