Other relevant investigations are the ones being made into the possibility of spontaneous life generation; even though we have seen some evidence that seems point to the existence of life in places other than Earth, which is still not conclusive enough. Also, it does not offer an explanation for life and therefore somewhat suspect. Many experiments on the generation of life have been conducted so far; Speaking at a conference on communicating with extraterrestrial intelligence (CETI), Carl Sagan is describing such a series, " . . . with this encouragement we can do the experiment one more time and mix together a mixture of methane, ammonia and water, supply it with energy and see what molecules are constructed." (And later on,) " . . . a wide variety of such experiments have been performed . . . and what we find is that not only are amino acids made in high yield but also the nucleotide bases and sugars, and indeed all the small fundamental building blocks of biochemistry."

     Mr. Sagan is presenting a formulation of the " . . . number of technological civilizations in the Milky Way at or beyond our level of technological advance." The formulation as devised by Frank Drake is as follows: N = R*fpnef1f;fc1.
This formulation is the central issue of the CETI conference and its factors are discussed at length by an international panel of scientists. The applicable ones are: the rate of star formation averaged over the lifetime of our Galaxy, the fraction of stars which have planetary systems, the mean number of planets within such planetary systems which are ecologically suitable for life, the fraction of such planets on which the origin of life actually occurs and the fraction of such planets on which intelligence arises. (For a fuller development, please refer to the proceeds of the CETI conference.) This formula is revealing the extent of extraterrestrial intelligence. Most of the factors in our formula can only be replaced by probable figures; at the present time these probabilities are not even statistical because we do not have any data at all on some of them. What we are talking about are subjective probabilities; their nature is defined by Terrence Fine thus, "The subjective view . . . encourages the holder to use his informal judgement, beliefs,