In an interesting version of the energy-time uncertainty principle Δt=τ/π, where τ is the time it takes Ψ(x,t) to evolve into a state orthogonal to Ψ(x,0). Test this out, using a wave function that is a linear combination of two (orthonormal) stationary states of some (arbitrary) potential: Ψ(x,0)=(1/2)[ψ1(x)+ψ2(x)].