(In the "Nineteenth Century")
In the beginning (about 2,000,000, mui 000 years ago) the universe was without form but not Void; it was a gas made up Of the simpler Wmits of matter, protons and electrons. It Was suffused with brilliant light, because it Was cts scalding density and hotness. In SAL tate innumerable interactions and com-nations went on between its particles, of longer possible in the universe These interactions built up the varieties of nuclei of the 92 sical sements, Many of these nuclei were radioactive, and decayed spontaneously owing to an inner instability; a few of the heavier ones, such as those of thorium and uranium, decay so slowly that some still remain even now.
The building up of the units of matter into complex nuclei released immense quantities of energy. This made the gas hotter and the pressure more intense, Under the impulse of the pressure the gas expanded, and cooled as it did so; the expansion stored potential energy of the matter as this spread outwards agains® its own mutual attraction. The universe of gas thus became much rarer, until space was almost void; also, owing to the cooling, "darkness was upon the face" of the universe. Many of the nuclei became linked with electrons to form neutral chemical atoms such as exist today upon the earth, save that all was as yet à rare gas, nothing was liquid or solid. The expansive forces were weakened by the fall of pressure and temperature. Chance concentrations and rarefactions in different regions gave play, here and there, to the mutual gravitational attraction of the gas. This began to condense towards numerous centres, forming separate clouds of gas of different sizes and irregular shapes, whose own attraction, however, in time made them spherical This was the beginning of the stars.
The stars were at first cool and rare, and their diameter far exceeded that of the sun as it now is; it exceeding even the diameter of the whole solar system, to the outermost planets: The surface of each star was then not far from that of the next, but the empty spaces between them increased as the stars contracted owing to the self-attraction of their own substance; moreover the stars continued to move apart with the pre-existing motion of general expansion of the gas, The universe had thus become a great mass of expanding star-gas, in which the huge stars themselves formed the "particles"; but some of the original gas remained here and there, aiid the process of condensation into stars has never wholly ceased.
Chance irregularities in the distribution of the stars led to lack of balance between their mutual attractions, and this i to them random motions s on general motion of separation. When these random motions brought two or three stars near to each other, their mutual attractions greatly distorted their shapes; they set each other rotating as they passed by. Often also pieces of their nearer parts broke off and formed planets, rotating about their own axes and revolving round their parent stars; many of the planets, being small, soon cooled and developed a solid crust. This formation of planets happened relatively often while the stars were still not widely separated, whereas now chance encounters between stars. can occur' extremely seldom.
As the star-gas expanded a stage came when chance irregularities in the distribution of the stars led (as had happened, on a different scale of space and time, with the primeval expanding gas) to a separation into many vast clouds of star-gas, of differing shapes and sizes, but each containing many billions (U.S.) of stars. These clouds set each other in. rotation, and this gave them the form of flattened revolving "discs" of star-gas; in many cases their mutual attractions drew "arms" outward from them, which took a spiral form as the clouds rotated. These clouds continued to separate, but even now their mutual distances do not very greatly exceed their own diameters; they are the spiral nebule, fi "island universes," of which our own galaxy or Milky Way, including the stars Visible to the naked eye the night sky, is one example. Our sun isa star of this galaxy nearer the edge than the centre.
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The individual stars in these many island galaxies. continued to contract; potential energy of gravitation was re-converted into heat as the outlying gas "fell" inwards upon, and the inner parts. The heat thus generated raised the internal pressure and temperature; this occurred specially near the centre, where the heat could least easily escape outwards through the overlying strata. The internal heat made the stars luminous, at first only with a dull red glow, later rising in brightness and becoming bluer. The fifiement of heaven thus shone with innumerable starry points.
e growing heat of the stars, in the hottest central regions, stripped the gas atoms of their outer company of reducing the gas to nuclei and electrons, as at an earlier stage; nuclear reactions again became possible, between protons (of which many still remained uncombined) and the nuclei of the light chemical elements lithium, beryllium and boron. This process released at energy, which long maintained the traction. When these light nuclei were all used up (at least in the hot central regions) another series of reactions began, in which carbon and nitrogen, without When the hydrogen fuel last used up, Sour may at last become as small as that of the or even less, though the mass may be immensely greater; the density therefore rises to high values (a few tons per cubic E Though the surface is bright, its area is so much reduced that the light from the
companion in this state, and perhaps 10,000,- is far less than before. Binns has a 000,000 years hence the sun and all stars we now see will share this fate. the earth (then cold and frozen) the sun will the future.
This is a brief paraphrase of the past and future history of our universe, as set forth in a new book, "The Birth and Death of the Sun, by George Gamow. The author is a brilliant young Russian professor of theoretical physics, now of the George Washington University in the United States capital. His story is, of course, in many respects still tentative. It is an essay. of outstanding excellence in the popular exposition of science.
The excellence of such a book depends largely on the selection of the salient material from the vast extent of science, and on the presentation of this material in suitable sequence. The author has himself made outstanding specialist contributions to the subject, but he remains able to see the field as a whole; and he is a delightful companion to the educated everyman who wishes to view the drama of material creation and evolution in its grandest outlines, During the last fifty years physics and astronomy have expanded in the most astonishing and unexpected ways: physics, by experiment and theory, has reached out towards the almost infinitely little, and astronomy, by observation and theory, has explored the vast spaces of the universe. Their progress, apparently in opposite directions, has led during the last two or three years to an amazing synthesis; the many mysterious discoveries in the sky and in the laboratory and study have fallen, like the pieces of a jigsaw puzzle, into a coherent picture of surpassíng grandeur.
The author names his story "The Birth and Death of the Sun," but the title "The Birth and Death of the Universe" would better fit his subject The process is depicted as moving in a definite direction from a beginning to an end, like the life of a man; but there remain many great questions; Who or What started the process? Is there not something beyond the "beginning" or the "end," which men may later be able to Is there a continuing purpose in it And is there not, in the actual universe, int that the picture does not, but should, include?
Text read from the printed page and cleaned; old type leaves the occasional error.