If I take two spherical regions of space about one metre in radius, they would contain about 10 ^ - 27 kg of dark energy each. If I now say that the centres of these regions are one metre apart, and assume that there is rest mass associated with dark energy (this rest mass being uniformly distributed in each of the spherical regions), then using Force = G m1 m2 / r^ 2 I would get a force of attraction for the spheres of 10^ -11 x 10^ -27 x 10^ - 27 / 1 x1 = 10^ -65 Newtons. If these two spherical regions obeyed Hooke's law F = - constant x extension then 10^ - 65 = k x 1 (I am assuming that earlier in the universe when it was smaller the centres of the spheres converged and at equilibrium there was no distance between them) k = 10^ -65 Let's postulate that the universe oscillates regularly between a big bang and a big crunch. The frequency of a harmonic oscillator is given by: w = ( k/m)^1/2 w = ( 10^ -65 / 10^ -27) ^ 1/2 w = 10^ -19 s^-1. So the universe would oscillate once every 10^ 19 seconds. Is my calculation a valid calculation?