A particle is in the ground state of the harmonic oscillator with classical frequency ω, when suddenly the spring constant quadruples, so ω′=2ω, without initially changing the wave function (of course, Ψ will now evolve differently, because the Hamiltonian has changed). What is the probability that a measurement of the energy would still return the value ℏω/2? What is the probability of getting ℏω? *Answer:* 0.943.