Summary

Randall acknowledges the important role that ordinary matter played in the formation of stars, planets, solar systems and galaxies. She also acknowledges the difficulties of finding the origins of life for the simple reason that no one can really define what life is. Nevertheless, she reviews some of the ideas that have been put forth to explain how life started on earth.

One is the notion of panspermia that comets or asteroids in effect seeded earth with the necessary elements and some of the basic structure of life.

Another hypothesis rests on the idea that earth has the conditions needed for the emergence of life—without the the need for extraterrestrial intervention.

There is no way to avoid the obvious fact that heavy elements such as carbon, nitrogen, phosphorus and sulfur originated in deep space, Randall says. Hydrogen...