Remarks on the Chemical Conditions on the Surface of the Primitive Earth and the Probability of the Evolution of Life

Abstract

The inner planets were formed from smaller objects that had no gases associated with them. These objects contained relatively small amounts of water and carbon in a form similar to that found in carbonaceous chondrites. The first forms of life must have originated during the time when the water reacted with the carbon (and also with nitrides, phosphides, etc.), while the hydrogen formed by this reaction was continuously lost from the gravitational field of the Earth. About 10⁴⁴ atoms of carbon reacted with water during less than 10¹⁷ s. The crucial question is whether some form of life will always develop under these conditions, or whether the origin of life is an improbable, perhaps an immensely improbable event. At present it is still impossible to answer this question.

On leave from the University of California, San Diego, La Jolla, Calif. 92037, U.S.A.

In the post-session discussion Professor Harold Urey expressed this in the following way: The evolution of life is not a miracle in the ordinary sense of the word, but it might be a ‘Fermi-Miracle’. A first order Fermi-Miracle is defined as an event that occurs with a probability of 1/10. A Fermi-Miracle n-th order is an event occurs with the probability of (1/10)ⁿ.