Inflation and primordial perturbations
Inflation is a proposed burst of extremely fast expansion in the first tiny fraction of a second that would explain why the universe is so uniform and flat and would seed galaxies from quantum fluctuations. It has passed several tests but is not confirmed, and the field that drove it is unknown.
Why it matters
Inflation links the largest structures to quantum physics at energies up to $\sim 10^{16}\,\mathrm{GeV}$, far beyond any accelerator.
Review
Planck Collaboration (Akrami Y. et al.), Planck 2018 results. X. Constraints on inflation, Astronomy and Astrophysics, 2020. https://arxiv.org/abs/1807.06211 reference checked
Editors' decisions
- Accept of version 2, , on 2026-10-15. Decision record
Timestamp record
- Signed record
- 690ffa5b7344…
- Public log
- Entry 189, in checkpoint 2,123
- In the log by
- Block 969,698, 2026-10-03
This text was in the PubPhys log by that date. The date says nothing about when the problem was first posed.