 The cosmologist Thomas Gold 1962 proposed just this. Believing that entropy values covary with the size of the universe, Gold asserts that at the maximum radius the thermodynamic arrow will “flip” due to the re-contraction. However, as Richard Tolman 1934 has shown in some detail, a universe filled with non-relativistic particles will not suffer entropy increase due to expansion, nor will an expanding universe uniformly filled with blackbody radiation increase its entropy either. Interestingly, Tolman demonstrated that more realistic universes containing both matter and radiation will change their entropy contents. Coupled with expansion, various processes will contribute to entropy increase, e.g., energy will flow from the “hot” radiation to the “cool” matter. So long as the relaxation time of these processes is larger than the expansion time scale, they should generate entropy. We thus have a purely cosmological method of entropy generation.