There is no explanation in the Big Bang theory for the seemingly fortuitous fact that the density of matter has just the right value for the evolution of a benign, life supporting universe.
Robert JastrowThe critical first billion years, during which life began, are blank pages in the earth's history.
Robert JastrowThe Universe is populated by innumerable suns, innumerable earths, and perhaps, innumerable forms of life. That thought expresses the essence of the Copernican revolution. No revelation more striking has ever come from the scientific mind.
Robert Jastrow