Part II. On the Possible Bases of a Universal Human Creed
Chapter 6: Life and the Planets
I. Living Planets in the Universe
1. From the point of view of the Immense: the apparent insignificance of the earth
From what we now know of astronomy the planets would seem at first sight to be a perfectly insignificant and negligible element in the
universe as a whole. How does the sidereal universe look to the eyes of modern science? No doubt you have gazed up at the sky on a fine winter’s night and, like innumerable human beings before you, had an impression of a serene and tranquil firmament twinkling with a
profusion of small, friendly lights, all apparently at the same distance from yourself. But telescopic and spectroscopic observation, and increasingly exact calculations, are transforming this comfortable spectacle into a vision that is very much more unsettling, one which in all probability will profoundly affect our moral outlook and religious beliefs when it has passed from the minds of a few initiates into the mass-consciousness of Mankind as a whole: immensities of distance and size, huge extremes of temperature, torrents of energy. . . .
That we may better understand what the earth means, we must try to penetrate, step by step, within this ‘infinity’.
First, the stars.
The stars constitute the natural sidereal unit. It is towards them therefore, the analysis of their structure and the study of their
distribution, that the researches of astrophysics are principally directed.
The process of research is one based entirely on the analysis of light, calling for miracles of patience, ability and acumen; but it is
astonishingly fruitful, since it enables exact measurements to be made of the mass, energy, diameter, distance and movement of objects vast in themselves but ultra-microscopic to us because of their remoteness.
The first thing to note is that, in certain aspects, the stars seem to vary a great deal among themselves. Certain of them, the ‘red giants’, are of colossal dimensions, their diameter exceeding 450 times that of the Sun (if the sun were as large as they it would extend beyond Earth, Jupiter and Saturn as far as Uranus!) Others, the ‘white dwarfs’, are smaller than the earth; and still others, the most numerous category, closely resemble the sun both in their dimensions and their yellow colour. We find similar contrasts of brilliance and temperature. One star may be the equivalent of 300,000 suns in luminosity, whereas another may amount to only a fifty-thousandth part of it (as great a difference, the astronomer Sir James Jeans observed, as there is between a lighthouse and a glow- worm). These, of course, are extreme cases. In the matter of surface- temperature, if the Sun and the majority of stars are round about 6,000•
Centigrade (three times the temperature of an electric arc) there are some of 11,000•(Sirius) and even of 23,000•; and on the other hand there are some as low as 3,500• (the red giants).
But beneath this great diversity, which is due principally to the varying ages of the stars, there is concealed a sort of deep identity. Whether giants, medium-sized or dwarfs, the stars are curiously similar in mass (from one to ten times the mass of the sun), which proves, incidentally, that they must vary prodigiously in their mean density -- 1.4 in the case of the Sun, but 50,000 and even 300,000 in the case of the dwarf stars (a fragment the size of a pinch of snuff, brought from one of these to
Earth, would weigh a ton!)
So we have approximate identity of mass, and therefore calibration. If we now consider the number of the stars (15,000 x 106 visible to the optical telescope alone) you will understand how it is possible to say, cosmically speaking, that we are enveloped in a sort of monstrous gas formed of molecules as heavy as the Sun moving at distances from each other so great that they have to be reckoned in light-years (bearing in mind that light travels at a speed of 186,000 miles per second, and that
we are only 8 light-minutes distant from the sun) -- a gas made of stars!
A gas of stars. The very conjunction of the two words is startling. But the shock is even greater when we learn that these myriads of suns scattered in the void are no more than the grains forming a super-grain of infinitely greater magnitude, and that this in its turn is no more than one unit amid a myriad of similar units! Imagination is confounded. . . . Yet this is what we learn, beyond any possibility of doubt, from the Milky Way and the other galaxies.
You will all have gazed in curiosity at the Milky Way, that long whitish ribbon which, extending from east to west over the two hemispheres, girdles our firmament. Astronomers have long felt that this mysterious, luminous train must constitute one of the most important structural features of the Universe. They sought, therefore, to decipher it, and they have succeeded in doing so. This is the conclusion, dumbfounding but certain, at which they have arrived. The Milky Way, they tell us, is not at all, as one might suppose, a sort of cloud of diffused matter drifting like a mist among the stars. Instead, it denotes the boundary, it marks the equatorial contour, of a prodigious lenticular accumulation of cosmic matter nursing, in its spiral arms, the solar system, all our
constellations, all our visible stars, and further millions besides (perhaps 100,000 x 106 altogether); these latter being so remote from us that they convey no more than a vague, milky impression to our eyes. It has been possible to calculate the dimensions of this extraordinary celestial formation and the speed with which it rotates upon itself. According to Jeans its diameter is about 200,000 light-years and it takes 3 million years to complete a single revolution, at a peripheral speed of several hundred miles per second. Compared with this stupendous disc, Jeans remarks, the earth’s orbit is no bigger than a pin’s head compared with the surface of the American continent.
But the Milky Way, our Milky Way, is not the only one of its kind in the Universe. Here and there small milky patches are to be discerned in the sky, which the telescope shows to be spiral clouds containing sparks of brilliance. These, as we now know, are infinitely further away from us than the stars. They do not belong to our own, immediate world -- or, as one might put it, to the sidereal vessel which bears us. They are other islands, other fragments of the Universe, other Milky Ways sailing in convoy with our own through space (or even diverging from it at fantastic speeds). Several millions of these galaxies have already been counted (each, we must remember, composed of millions upon millions
of stars), separated from one another by an average distance of 2 million light-years, and all of approximately the same size! A gas of galaxies on top of a gas of stars. . . . This is the truly overwhelming spectacle, far beyond our power to picture it, in which our present vision of the Universe culminates when we look in the direction of the Immense.
But must we not assume, following the logic of this principle of
recurrence, that even beyond this there are super-galaxies, each formed of a group of spiral nebulae? We cannot be sure, but it seems
improbable. The Universe is not composed, as Pascal thought, of pieces enclosed one in another, repeating themselves indefinitely and
identically from bottom to top, from the infinitesimal to the immense.
At a certain level the cosmic structure stops dead, and we pass on to
‘something else’. Beyond the galaxies there is nothing, according to Einsteinian physics, unless it be the spherical frame of Space- Time within which all things move in a circle, without ever coming to an end or being able to leave it. . . . Let us put aside this still unresolved
problem of the upper limits of the world, and since we do not yet know what may be beyond or around the galaxies, let us at least consider what unites them -- that is to say, try to describe the genesis of their swarm. It is along this path, as you will see, that we shall eventually encounter the planets in search of which we started out.
At the very beginning, so the astronomers tell us -- that is to say,
billions of years ago -- there was in place of the present world a diffused atmosphere, billions of times less dense than air, spreading in all
directions over billions of miles. This ‘primordial chaos’, as Jeans calls it, must have seemed homogeneous; but inasmuch as it was subject to the force of gravity it was excessively unstable. A slight unevenness of distribution occurring by chance at any given point (a contingency that was bound to arise) was all that was needed to cause the entire edifice to break up into parts which, sundering themselves from their neighbors, coiled in more and more tightly upon themselves in enormous clots -- their vastness, by the law of celestial mechanics, being directly
proportionate to the lightness of the matter of which they were
originally composed. This was the first stage of the birth of the galaxies.
The same disruptive process then operated within the separate galaxies, engendering smaller clots, since cosmic matter had become heavier.
Thus the stars appeared.
Are we then to suppose that a third stage occurred in which the stars, in their turn, gave birth to planets through the condensation of their
substance? This was the famous theory of Laplace; but a more thorough analysis of the problem has shown that it could not have happened in this way. Astronomers are today agreed that the distribution and
movement of the heavenly bodies composing the solar system can only be explained by the hypothesis of a purely fortuitous occurrence -- for example, the near contact of two stars. This is to say that Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus or little Pluto, the furthest of all, would not exist had not another Sun, by an extraordinary chance, passed so near to our Sun as almost to touch it (within three diameters!) wresting from it, by force of attraction, a long, cigar-shaped filament which in the course of time broke up into a string of separate globes.
And this brings us to the heart of the problem we set out to solve, namely: What is the place, the significance and the importance of our planets in the Universe?’
Because of their very small dimensions (even Jupiter is a dwarf compared with the Sun), the extreme weakness of the energy they radiate, and the short time they have been in existence (the galaxies were billions of years old when the solar system was born); even more important, because of their mode of existence, the planets look not merely like poor relations but like strangers and intruders in the sidereal system. Created by chance, they have no place in the normal and
orthodox evolution of astral matter; with the exasperating result that we know nothing for certain about the existence or frequency of occurrence of planets outside the solar system. In Laplace’s thesis almost every star should have its girdle of planets. In present-day theory perhaps one star in 100,000 (Jeans’s estimate: Eddington puts the figure at millions) possesses them. And if to this we add the fact that, in the case of any given planet, it calls for a further extremely rare accident to produce the conditions which would endow it with life, we can see what a
fantastically small figure, quantitatively speaking, our Earth cuts in the Universe.
I said just now, in seeking to describe the magnitude of the human events which are overtaking us, that they were of ‘planetary’
importance. But is not ‘planetary’ almost synonymous with
‘infinitesimal’? Let me recall from memory the hard words of Jeans (he wrote more hopeful ones later, you will be relieved to learn): ‘What does life amount to? We have tumbled, as though through error, into a universe which by all the evidence was not intended for us. We cling to a fragment of a grain of sand until such time as the chill of death shall
return us to primal matter. We strut for a tiny moment upon a tiny stage, well knowing that all our aspirations are doomed to ultimate failure and that everything we have achieved will perish with our race, leaving the