DID THE UNIVERSE EVOLVE

A new type of explanatory mechanism is proposed to account for the fact that many of the dimensionless numbers which characterize particle physics and cosmology take unnatural values. It is proposed that all final singularities 'bounce' or tunnel to initial singularities of new universes at which point the dimensionless parameters of the standard models of particle physics and cosmology undergo small random changes. This speculative hypothesis, plus the conventional physics of gravitational collapse, together comprise a mechanism for natural selection, in which those choices of parameters that lead to universes that produce the most black holes during their lifetime are selected for. If our universe is a typical member of the ensemble that results from many generations of such reproducing universes than it follows that the parameters of our present universe are near a local maximum of the number of black holes produced per universe. Thus, modifications of the parameters of particle physics and cosmology from their present values should tend to decrease the number of black holes in the universe. Three possible examples of this mechanism are described. In inflation models I show that, given the hypotheses, there is selective pressure for the very small values of scalar field self-coupling required for inflation. The second concerns the effect on changing the proton-neutron mass difference on the rate of black hole formation in our galaxy. I argue that changing the sign of the mass difference results in a large decrease in the number of black holes produced. Whether raising it results in a decrease or an increase in black hole production is difficult to determine because of the intricate physics of the star formation process. The third mechanism is that in cold, or tepid, big bang models, changes in the proton-neutron mass difference could strongly effect the evolution of the universe as a whole.