IN STARRY SKIES

Evening Post, Volume CXV, Issue 123, 27 May 1933, Page 22

IN STARRY SKIES

AN EXPANDING UNIVERSE

(By "Omega Contauri.")

•Wo'live somewhere in. the midst of a marvellous. series of worlds within worlds. The infinitesimal appears to be just as wonderful as tho infinitely great. Wo can peer only a limited distance into each, and can merely speculate on what lies beyond. It ia distinctly dangerous to bo too dogmatic. Tho wisdom of tho past has been proved to be mixed with error, and it would bo very rash to,suppose that now at last we have reached finality. The indications indeed aro just the other way. Tho pendulum of scientific opinion is rather apt to swing so violently that in breaking free from one error, it flies to ' another. The nineteenth ■ century presented us with a depressing ' pieturo of a glorious universe attacked by tho germs of decay, and steadily, even if extremely slowly, moving towards eternal death, through the aggregation of matter and tho dissipation of energy. Now we are offered a picture of the past and future which is more spectacular but in no respect more satisfactory. Its details are mostly blurred and indistinct, though oceasionalfy we are startled by some precise numerical statement of the value of some quantity that appears to most of us to be beyond, the possibility of discovery by human intelligence, such for instance as the total number of electrons in the whole universe. Fortunately the picture of the future is for ever changing, so if we are unsatisfied with its aspect today, we may hope for better things tomorrow. Man's knowledge of tho universe is yet in its infancy. We can set no limits to the possibilities of its growth. But liowovcr wonderful future discoveries may be, and indeed almost certainly will be, the real universe must far transcend any conception of it, formed by beings isolated on,, ones living ■ speck

in its infinity. Today wo must glaneo at ono of the latest views with regard to evolution and the impending fato of this universe. It is not easy,-how-ever, to form any clear idea of what the loading scientists of today actually mean. Nineteenth century science may have been mistaken, but it was clear and distinct. Twentieth century scionco appears to the layman full of contra- j dictions and absurdities. Its exponents delight especially in paradox, aud cannot bear any appeal to common sense. Explorations in either direction, among the subatomic entities in the matter around us, or among the yast systems •in the remotest regions of space, are dependent chiefly on tho messages-of light. All ■must marvel at bho wealth of facts which this single agent, has revealed. Our earth, which seemed so large, has turned out to be one of the smaller planets of a dwarf suu in a gigantic galaxy. This galaxy is not alone. It appears to be a unit in a vast system of a higher order. But what, of tho whole hosts of -galaxies'? Do they form a unit iv a system still more immense? Is there any limit to the series of worlds within worlds? It seems extremely rash to set any such limit, but modern writers do not hesitate 'to do so. Sir Arthur- Eddington, for instance, in "The Expanding Universe," published in 1933, gives numerical results which he considers, to be not likely in error by more than a factor 2. these, are: The total mass of the universe in grams, the number of protons, and the number of electrons in it, and the initial radius of the universe before it began to expand. Expansion by the way is a very mild term for the stato of > affairs presented for our consideration. Explosion would be more in keeping with the facts. Eddington pictures the .universe as having been formed by'the gradual condensation of primordial matter. Protons and electrons in the first stage were traversing /ho void. They, gradually combined into greater systems until at present a hundred thousand million stars make one galaxy, and a hundred thousand million galaxies ono universe. This use of tho word "one" is peculiar. Does it mean that he uses the term universe for cosmic system and not for everything that exists1? Now the hypothesis of an explosion actually iv progress rests partly on theory and partly on observation. The observational fact is that tho light of the most distant spirals is reddened, its wave frequency being slowed down. Doppler's principle seems to act splendidly within our own galaxy. By minute changes in

the lines of tho spectrum astronomers can tell us whether each star, that sends :us sufficient light, is moving towards us or from us, and can measure tho relative velocity in miles per second. But when we come to such distant systems as tho spiral nebulae a strange fact is noted. Out of niuety line-of-sight velocities determined, only live are towards us. Further, the velocities seem to increase with distance, and at present a nebula in Gemini, which' is 1 estimated to be 150,000,000 light years away, holds tlio record for speed of recession, 15,000 miles .per second. ■ The question is whether this apparent motion is real, or whether tho wave frequency has been slowed down during the 150,000,000 years that tho light lias been on its way to us, through the vast reaches of space that wo know arc traversed by flying atoms and other particles. Tho '■resent data would undoubtedly be insufficient to build more than a tentative theory had not certain mathematical investigations suggested something of tho same kind. The relativists offer us a choice of many different universes, each evolved out of the inner consciousness, and then tested by some reference to observational facts. If not satisfied with the original Einstein universe, or any of its subsequent modifications, we may adopt in its*stead' j the de Sitter universe, the Lemaitre one, or take our choice from those of Friedmann, Dirac, Wey], McVittio, McCrea, Bobortson, Eddington, or any other we please. If the .theory doesn't fit the facts we have only to add [ another term to one side' of our equation and make it do so. Eddington • explains that Einstein's theory . did. not work properly as he approached infinity. Ho tella us that Einstein showed his greatness in a I simple and drastic way. "He abolished infinity! Ho slightly altered his equa- ! tioits ho as to make spnee at great distances bend round until it closed up."] | Then de Sitter predicted by the relativity theory that the velocity of rci cession of distant systems would appear i proportional to tho squaro of tho disI tanco. In de Sitter's universe the re- | cession is too large, iv Einstein's there

lis none. ■ But: a compromise has been effected and simple proportionality to ' distance is said to bo theoretically cor-1 rect. It is strange how the fate of.tho whole universe seems to depend on tho additional terms that individual thinkers deeido to add to one or the other side of an equation. The term which Einstein added at one stage is said to give rise to de Sitter's cosmical repulsion. The conceptions of the universe and its destiny, so briefly and inadequately referred to here, are impossible to picture clearly, for they involve tho mixing up of time and space, tho multiplying of time measurements by the square root of minus one, the curvature of space, the finite but unbounded, or perhaps the infinite but bounded, character of the universe. Einstein^s universe we are told contains matterbut no motion, whilst de Sitter's contains motion but no matter. Eddington reaches the conclusion that tho world started as an Einstein universe, passed continuously along tho series of models, and will finish up as a de Sitter universe, one full of motion though absolutely devoid of anything that can move.