STARRY HEAVENS

Southland Times, Issue 22188, 2 December 1933, Page 11

STARRY HEAVENS

THE EXPANDING UNIVERSE.

(By

R. D. Thompson, M.A., M.Sc., F.R.A.S.)

BRITISH ASSOCIATION MEETING. Ji is reported that at the recent British Association meeting held at Leicester which was attended by eminent scientists from all countries of the world, none of the discussions aroused greater interest or attracted larger audiences than those which were devoted to atomic transmutations and to the theory of the expanding universe. Professor Regener, of Stuttgart, described recent investigations on cosmic radiation —those mysterious highlypenetrating rays of unknown origin which reach the earth from all directions of space. By means of measuring instrumenst attached to balloons the intensity of cosmic radiation has now been measured up to a height of 16} miles in the stratosphere, and in one ascent on a day on which there was a magnetic disturbance, it was found that the intensity registered was 15 per cent, greater than on other occasions. Lord Rutherford reviewed the history of twenty-five years’ work on atomic transmutation, and described the stages of the brilliant experimental work which has culminated in the successful “splitting” of the atom. Lord Rutherford warned his audience that there was no likelihood of any great source of power being obtained from atomic transformations, and he pointed out that the subject was of interest mainly in revealing the nature and structure of the atom rather than in its bearing on the production of chemical or industrial power. In the Astronomical Section a discussion on the “expanding universe” theory was initiated by Professor Sir A. S. Eddington, one of the leading English exponents of the theory of relativity. “This discussion,” states the London Observer, “indicates the strength of popular as well as scientific interest, not merely in the origin and mechanism of life, but in its ultimate destinies. Not even the recondite or abstruse mathematical calculations involved deterred a large audience from attempting to follow discussions which, if mathematical in technique, are yet essentially philosophical. Popular difficulties in tills field are, however, scarcely lightened by the differing views of the experts when almost all save the physicist himself, must accept on trust, for example, Professor Eddington’s contention that relativity theory affords some confirmation of astronomical observations that the galaxies, or spiral nebulae, are scattering at a rate which doubles their distance from us and from one another in about 1300 million years. The interest taken in such discussions testifies to the vigour of scientific thought, and to man's almost universal attempt to grope through to some satisfying philosophy of existence.” Spiral Nebulae. The term “nebula” was at first indiscriminately applied to all celestial objects of an ill-defined, hazy character which would not be resolved into separate stars by the naked eye. The telescope and photography have since shown that many of these cloud-like structures are simply huge clusters of individual stars, and it was then drought that as the power of telescopes increased, all such nebulae would ultimately be resolved into component stars. Such, however, was not proved to be the case, and the nebulae are now divided into two main classes — the “gaseous” nebulae, which, as the name implies, are probably composed of gas or fine cosmic dust, and are irregular in outline and diffuse in character—together with ■ the “spiral” nebulae, all of which appear to be more or less regular in pattern, and resemble “vast whirlpools of light” with a central nucleus surrounded by fainter spiral formations. Island Universes. The spiral nebulae, whose numbers are now known to run into millions, afford one of the most baffling problems of modern astromony. Measurements have shown that in comparison with other celestial objects they are incredibly remote in space, some at distances exceeding even 100 million light years. Some idea of this enormous scale of distance may be gained when it is remembered that the sun is only 8} light minutes distant from the earth, and the nearest star 4} light years from the sun Other stars are separated at distances of hundreds and even thousands of light,years, but nothing approaches the millions of light | years of the spiral nebulae. It has therefore been held by many prominent astronomers that these spiral nebulae should properly be regarded as entirely separate “island” universes, or galaxies, and that all the stars visible in the sky, together with the Milky Way, form only one such system. 15,000 Miles a Second. Not only are these other universes so enormously remote from our own particular stellar system, but it vzould appear that they are actually moving farther away at terrific speeds, and the farther they move away, the faster they go! The universe as a whole would therefore seem to be scattering or “expanding,” and it is the observational determination of this fact which Professor Eddington speaks of ,as being confirmed by the relativity theory. It was in 1917 that Professor W. de Sitter brought forward his famous “expanding universe” hypothesis, in which he predicted that distant objects should be receding still farther away at huge velocities, although at the time of his announcement the then available experimental evidence was insufficient to confirm his theoretical deductions. De Sitter’s mathematical investigations were based upon Einstein’s relativity theory of gravitation, and Professor Eddington has pointed out that the universe, according to this theory, must necessarily be in an unstable condition, so that either a continuous expansion, or else a contraction, is an inevitable result of Einstein’s law of gravitation. Why there should actually' be expansion rather than contraction is still undetermined, but once started, the expansion or contraction must continue at an increasing rate. Recent measurements show that some spiral nebulae , are receding nt speeds up to 15,000 miles a second, which amounts to one-twelfth of the velocity of light itself. Objects moving anart at a speed greater than the speed of light would utterly vanish in so far as any knowledge of the presence or movements of one could be ascertained from the other; to all intents and purposes they would ass into entirely separate worlds. Professor Eddington uses the phrase “sink below the horizon,” and suggests that probably a great part of the universe is already below our horizon. “Thus, in time,” he says, “the universe will become virtually a number of disconnected universes no longer bearing any physical relation to one another.”