First, proponents could not devise a plausible mechanism to explain the successive reexpansions of the universe after the gravitational collapses they envisioned. Even on the somewhat implausible assumption that something like the expansion force of the cosmological constant would reinflate the universe after each collapse, the model ran into difficulties with the second law of thermodynamics, as MIT physicist Alan Guth demonstrated in 1984.53 (The second law says that the disorder or entropy of an isolated system of matter and energy will increase over time.)
