Page:Astounding Science Fiction v54n06 (1955-02).djvu/137

 that in all that time, Earth has been just as rich in hemoglobin as it is now. If that were true, the total number of hemoglobin molecules ever to have existed on Earth would be 10$50$. This is still nowhere near the hemoglobin number.

Well, then, let us stop fooling around with one dinky little planet and its history. We have all of space and time at our disposal and as science-fiction enthusiasts we ought to have no

qualms about using it. It is estimated that there are one hundred million stars in the galaxy and at least that many galaxies in the universe. Let's be generous. Let's never stint in our generosity. Let's suppose that there are a billion stars in the galaxy, rather than merely a hundred million. Let us suppose there are a billion galaxies in the universe. The total number of stars in the universe would then be 10$9$ x 10$9$ or 10$18$.

Suppose now that every star—every single star—possessed in its gravitational field no less than ten planets, each one of which was capable of holding as much life as Earth can and that each one was as rich in hemoglobin. There would then be IO19 such planets in existence and in one year, the number of hemoglobin molecules that would have existed on all those planets—assuming always a life-expectancy of a third of a year for each molecule—would be 3 x 10$59$.

Now let us suppose that each of these planets remained that rich in hemoglobin for, from first to last, three hundred billion years—3 x 10$11$. This is a very generous figure, really, since the sun's life expectancy is only about ten to twenty billion years, during only a portion of which time will life on Earth be possible. And this life expectancy is rather longer than average for other stars, too.

Still, with all the generous assumptions we have been making, all the hemoglobin molecules that could possibly exist in all the space and time we have any knowledge of—and more—comes out to 10$71$. This number is still virtually zero compared to the hemoglobin number.

Let's try a different tack altogether. Let's build a computing machine—a big computing machine. The whole known universe is estimated to be a billion light-years in diameter, so let us imagine a computing machine in the form of a cube ten billion light-years on each edge. If such a machine were hollow, there would be room in it for one thousand universes such as ours, including all the stars and galaxies and all the space between the various stars and galaxies as well.

Now let us suppose that computing machine was completely filled from edge to edge and from top to bottom with tiny computing units, each one of which could test different combinations of hemoglobin amino acids in order to see whether it was the hemoglobin combination or not. In order to RV 138