The inflaton field rolls down its potential, driving exponential expansion of the universe
Inflation is driven by a scalar field φ rolling on potential V(φ). Equations:
φ̈ + 3Hφ̇ + V'(φ) = 0
H² = (φ̇²/2 + V)/(3M²ₚₗ)
Slow-roll: φ̈ ≈ 0, ε = (V'/V)²/2 ≪ 1. Inflation ends when ε = 1.
e-folds: N = ∫H dt ≈ 60 needed to solve flatness/horizon problems.
Quantum fluctuations δφ generate the CMB temperature anisotropies.