Inflation as a semiclassical instability*

We show that the semiclassical Einstein equation with a quantized massive scalar field permits exact static solutions. The curvature and cosmological constant Λ in the solution arise as quantized values associated to the eigenstates of the scalar field. Linear stability analysis reveals stable and unstable modes that are functions of Λ, and independent of the size and curvature of the static universe. The unstable mode leads naturally to an inflating "emergent" universe.