We determine the first two
derivatives of the classical Boltzmann–Shannon entropy of the conjugate heat
equation on general evolving manifolds. Based on the second derivative of the
Boltzmann–Shannon entropy, we construct Perelman’s ℱ and 𝒲 entropy in abstract
geometric flows. Monotonicity of the entropies holds when a technical condition is
satisfied.
This condition is satisfied on static Riemannian manifolds with nonnegative Ricci
curvature, for Hamilton’s Ricci flow, List’s extended Ricci flow, Müller’s Ricci flow
coupled with harmonic map flow and Lorentzian mean curvature flow when the
ambient space has nonnegative sectional curvature.
Under the extra assumption that the lowest eigenvalue is differentiable
along time, we derive an explicit formula for the evolution of the lowest
eigenvalue of the Laplace–Beltrami operator with potential in the abstract
setting.