From big bang to black holes: the beginning and the end of time

Observations have revealed a systematic red shift of light from distant galaxies. Interpreted as a Doppler shift, it indicates a recession of galaxies from us. It is usual to hypothesize that this recession is not peculiar to our locale but is universal and that there is a uniformity in the entire universe. Models of the universe built up in this way lead to a collapsed state of the universe at a finite past. This is termed the Big Bang and classical physics breaks down at this stage. One presents this as a beginning of everything. In a way, a reverse situation occurs in the case of massive stars at the end of thermonuclear energy generation. Gravitation is then counter-balanced by the degeneracy pressure of fermions. However, equilibrium can he obtained only up to a limiting mass—a fact originally discovered by -Chandrasekhar in case of electron degeneracy. At higher densities, the predominant pressure may be due to neutron degeneracy and the mass limit is then about three times the solar mass. For higher masses, an uncontrolled collapse occurs to the stage of a black bole when it can no longer send any signal outside. Still later, classical physics predicts a state of infinite density. The big bang and the black hole apparently signal the beginning and the end of time. Right now one can only hope and speculate that quantum ideas will show a way out.