IS THE UNIVERSE LIMITLESS?

Evening Star, Issue 23174, 25 January 1939, Page 2

IS THE UNIVERSE LIMITLESS?

SCIENCE FINDS NEW KIND OF STAR CLOUD 300,000 LIGHT YEARS OFF Not all the work of astronomy is done by the biggest telescope. The 100-inch reflector on Mount Wilson, turning away from its chief task of revealing the mega-universe, the universe of universes, has just picked out'two more moons of Jupiter’s brood, but hitherto the most successful moon-finder has been the 30in refractor on Mount Hamilton, which James Lick paid to put there in the hope of having the biggest and best telescope in the world for his funeral monument. He is buried beneath it, writes E. S. Grew, in the Loudon ‘ Observer.’

On Mount Palomar the work is steadily proceeding on the 200 in reflector, which is to enlarge the powhr and dominion of its lOOin brother and help to carry a stage farther the question whether the greater universe is limitless, filled, as with worlds without end, with flying universes racing away till light can no longer catch them up. It may leave the question as undecided as before, or it may compel astronomers and mathematicians to be-. lieve that there is some law of Nature undiscovered which organises the universal flight, such as that of a gravity which is a push rather than a pull. Or it may simply show, as Sir Arthur Eddington seemed to suggest, that there may be something wrong in the way the universes have been counted. Counting is the largest preoccupation of observatories, great and small. Meanwhile, the comparatively modest 60in reflector which Harvard Observatory maintains at Bloemfontein, in South Africa, has discerned a most remarkable congregation of stars, which have hitherto escaped the perception of the bigger light-grasping powers of Mount Wilson’s giant. Dr Howard Shaplcy described it at Cambridge as' an extremely faint star system of an unknown kind. It is not a globular cluster, one of those balldike assemblages of stars which are like sentinels of our Milky Way, and seem to be flying inward towards it. Nor is it an assembly of stars like those of the Magellanic clouds, which are like banners floating from the Milky Way and may not be in any way related to it. Nor yet is it a spheroidal group, a regularly shaped island of stars, floating away by itself. But it is like all three of these concourses. It is an immense aggregation of stars, of which 5,000 have been counted, and its light takes 300,000 years to reach us; or to adopt some of the astronomer’s benumbing distances, it is 18,000,000 billion miles away. It is nevertheless part of the territory of our Milky Way, and it may be the farthest, the very farthest, promontory of it. It is one of the commonplace miracles of astronomic observation that a way has been found to find the probable distance of an object so faint, and stars so distant, with some approach to certainty. It is done by noting among the 5,000 stars that have been counted some of those pulsating stars, the Cepheid variables, which partake of the nature of revolving lighthouses and are at the same time the astronomer’s receding lamp-posts of the sky. All these variable stars, wherever thev are found, have a real brightness which depends precisely on the time they take to wax and wane iu their pulsation. Consequently their real brightness is always known, and when this is compared with their apparent brightness, as ascertained by the astronomer’s most delicate light measuring instruments, then by rule of three their distance also becomes known. These calculations, as we need hardly point out, are the task of the most patient observers; and the study of the Cepheid, pulsating stars, and the reasons why they pulsate is a branch of astronomy likely to occupy the calculators and the counters for many years to come.

The general idea is that they blow up like a balloon from the expansion of the star’s hot gases, and then deflate from the pull of gravity, drawing the gas particles hack again. But this mechanism leaves many things unexplained. Another aspect of the importance of counting was revealed by Dr Howard Shapley in recording the observations made by the lesser telescopes of the number and distribution of the distant universes, the spiral nebulae, as seen through what he calls a “galactic window,’’’ a view through an open space in our Milky Way.

He told the astronomers at Cambridge that large inequalities in the distribution of these migrating flows were discernible. Across the South Pole of our Milky Way these distant replicas of our own particular universe show what he calls a major inequality of density of distribution. This we take to moan that they cluster much more thickly in one direction than another.

This observation, if confirmed, clashes with the idea that however far we peer with the lOOin or 200 in reflector into space we shall find distant universes spread out in orderly succession. We may not. Then we shall have to begin all over again to try to frame a Cosmogony, with that high degree of probability of which old Simon Newcombe said, at the end of his long and fruitful career as an astronomer, he still entertained a doubt.

We do not even know the shape and stability of our own Milky Way, which by the latest accounts shows a puzzling lopsidedness. It is generally held that the centre or apex of this immense revolving disc of million upon millions of stars is the same as that of the far loss imposing number of globular clusters which revolve with it. Theirs is a problem

yet unsolved ; but it seems to be clear that the two centres do not agree, and this fact, combined with the other disturbing fact that the stars rotating fastest are inward bound anti the slower ones arc moving outward, docs n-' J - fit iu with the idea of a steady universe.