Solving Einstein's Equations for Binary Black Hole Spacetimes

Constraint Damping in Electromagnetism
Electromagnetism is described as the hyperbolic evolution
equation ∇ a ∇ a A b = ∇ b H.
Where have the usual ⃗ ∇ · ⃗E = ⃗ ∇ · ⃗B = 0 constraints gone?
Gauge condition becomes a constraint: 0 = C ≡ ∇ a A a − H.
Maxwell’s equations imply that this constraint is preserved:
∇ a ∇ a
(
∇ b A b − H ) = ∇ a ∇ a C = 0.
Lee Lindblom (Caltech) Binary Black Holes UW Milwaukee 10/14/2011 11 / 32