Part 1 (1/2)

The Outline of Science.

by J. Arthur Thomson.

INTRODUCTION.

There is abundant evidence of a widened and deepened interest in modern science. How could it be otherwise when we think of the magnitude and the eventfulness of recent advances?

But the interest of the general public would be even greater than it is if the makers of new knowledge were more willing to expound their discoveries in ways that could be ”understanded of the people.” No one objects very much to technicalities in a game or on board a yacht, and they are clearly necessary for terse and precise scientific description. It is certain, however, that they can be reduced to a minimum without sacrificing accuracy, when the object in view is to explain ”the gist of the matter.” So this OUTLINE OF SCIENCE is meant for the general reader, who lacks both time and opportunity for special study, and yet would take an intelligent interest in the progress of science which is making the world always new.

The story of the triumphs of modern science is one of which Man may well be proud. Science reads the secret of the distant star and anatomises the atom; foretells the date of the comet's return and predicts the kinds of chickens that will hatch from a dozen eggs; discovers the laws of the wind that bloweth where it listeth and reduces to order the disorder of disease. Science is always setting forth on Columbus voyages, discovering new worlds and conquering them by understanding. For Knowledge means Foresight and Foresight means Power.

The idea of Evolution has influenced all the sciences, forcing us to think of everything as with a history behind it, for we have travelled far since Darwin's day. The solar system, the earth, the mountain ranges, and the great deeps, the rocks and crystals, the plants and animals, man himself and his social inst.i.tutions--all must be seen as the outcome of a long process of Becoming. There are some eighty-odd chemical elements on the earth to-day, and it is now much more than a suggestion that these are the outcome of an inorganic evolution, element giving rise to element, going back and back to some primeval stuff, from which they were all originally derived, infinitely long ago. No idea has been so powerful a tool in the fas.h.i.+oning of New Knowledge as this simple but profound idea of Evolution, that the present is the child of the past and the parent of the future. And with the picture of a continuity of evolution from nebula to social systems comes a promise of an increasing control--a promise that Man will become not only a more accurate student, but a more complete master of his world.

It is characteristic of modern science that the whole world is seen to be more vital than before. Everywhere there has been a pa.s.sage from the static to the dynamic. Thus the new revelations of the const.i.tution of matter, which we owe to the discoveries of men like Professor Sir J. J. Thomson, Professor Sir Ernest Rutherford, and Professor Frederick Soddy, have shown the very dust to have a complexity and an activity heretofore unimagined. Such phrases as ”dead” matter and ”inert” matter have gone by the board.

The new theory of the atom amounts almost to a new conception of the universe. It bids fair to reveal to us many of nature's hidden secrets. The atom is no longer the indivisible particle of matter it was once understood to be. We know now that there is an atom within the atom--that what we thought was elementary can be dissociated and broken up. The present-day theories of the atom and the const.i.tution of matter are the outcome of the comparatively recent discovery of such things as radium, the X-rays, and the wonderful revelations of such instruments as the spectroscope and other highly perfected scientific instruments.

The advent of the electron theory has thrown a flood of light on what before was hidden or only dimly guessed at. It has given us a new conception of the framework of the universe. We are beginning to know and realise of what matter is made and what electric phenomena mean. We can glimpse the vast stores of energy locked up in matter. The new knowledge has much to tell us about the origin and phenomena, not only of our own planet, but other planets, of the stars, and the sun. New light is thrown on the source of the sun's heat; we can make more than guesses as to its probable age. The great question to-day is: is there one primordial substance from which all the varying forms of matter have been evolved?

But the discovery of electrons is only one of the revolutionary changes which give modern science an entrancing interest.

As in chemistry and physics, so in the science of living creatures there have been recent advances that have changed the whole prospect. A good instance is afforded by the discovery of the ”hormones,” or chemical messengers, which are produced by ductless glands, such as the thyroid, the supra-renal, and the pituitary, and are distributed throughout the body by the blood. The work of physiologists like Professor Starling and Professor Bayliss has shown that these chemical messengers regulate what may be called the ”pace” of the body, and bring about that regulated harmony and smoothness of working which we know as health. It is not too much to say that the discovery of hormones has changed the whole of physiology. Our knowledge of the human body far surpa.s.ses that of the past generation.

The persistent patience of microscopists and technical improvements like the ”ultramicroscope” have greatly increased our knowledge of the invisible world of life. To the bacteria of a past generation have been added a mult.i.tude of microscopic animal microbes, such as that which causes Sleeping Sickness. The life-histories and the weird ways of many important parasites have been unravelled; and here again knowledge means mastery. To a degree which has almost surpa.s.sed expectations there has been a revelation of the intricacy of the stones and mortar of the house of life, and the microscopic study of germ-cells has wonderfully supplemented the epoch-making experimental study of heredity which began with Mendel. It goes without saying that no one can call himself educated who does not understand the central and simple ideas of Mendelism and other new departures in biology.

The procession of life through the ages and the factors in the sublime movement; the peopling of the earth by plants and animals and the linking of life to life in subtle inter-relations, such as those between flowers and their insect-visitors; the life-histories of individual types and the extraordinary results of the new inquiry called ”experimental embryology”--these also are among the subjects with which this OUTLINE will deal.

The behaviour of animals is another fascinating study, leading to a provisional picture of the dawn of mind. Indeed, no branch of science surpa.s.ses in interest that which deals with the ways and habits--the truly wonderful devices, adaptations, and instincts--of insects, birds, and mammals. We no longer deny a degree of intelligence to some members of the animal world--even the line between intelligence and reason is sometimes difficult to find.

Fresh contacts between physiology and the study of man's mental life; precise studies of the ways of children and wild peoples; and new methods like those of the psycho-a.n.a.lyst must also receive the attention they deserve, for they are giving us a ”New Psychology” and the claims of psychical research must also be recognised by the open-minded.

The general aim of the OUTLINE is to give the reader a clear and concise view of the essentials of present-day science, so that he may follow with intelligence the modern advance and share appreciatively in man's continued conquest of his kingdom.

J. ARTHUR THOMSON.

I.

THE ROMANCE OF THE HEAVENS.

THE SCALE OF THE UNIVERSE--THE SOLAR SYSTEM.

-- 1.

The story of the triumphs of modern science naturally opens with Astronomy. The picture of the Universe which the astronomer offers to us is imperfect; the lines he traces are often faint and uncertain. There are many problems which have been solved, there are just as many about which there is doubt, and notwithstanding our great increase in knowledge, there remain just as many which are entirely unsolved.

The problem of the structure and duration of the universe [said the great astronomer Simon Newcomb] is the most far-reaching with which the mind has to deal. Its solution may be regarded as the ultimate object of stellar astronomy, the possibility of reaching which has occupied the minds of thinkers since the beginning of civilisation. Before our time the problem could be considered only from the imaginative or the speculative point of view. Although we can to-day attack it to a limited extent by scientific methods, it must be admitted that we have scarcely taken more than the first step toward the actual solution.... What is the duration of the universe in time? Is it fitted to last for ever in its present form, or does it contain within itself the seeds of dissolution? Must it, in the course of time, in we know not how many millions of ages, be transformed into something very different from what it now is? This question is intimately a.s.sociated with the question whether the stars form a system. If they do, we may suppose that system to be permanent in its general features; if not, we must look further for our conclusions.

The Heavenly Bodies.

The heavenly bodies fall into two very distinct cla.s.ses so far as their relation to our Earth is concerned; the one cla.s.s, a very small one, comprises a sort of colony of which the Earth is a member. These bodies are called planets, or wanderers. There are eight of them, including the Earth, and they all circle round the sun. Their names, in the order of their distance from the sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Ura.n.u.s, Neptune, and of these Mercury, the nearest to the sun, is rarely seen by the naked eye. Ura.n.u.s is practically invisible, and Neptune quite so. These eight planets, together with the sun, const.i.tute, as we have said, a sort of little colony; this colony is called the Solar System.

The second cla.s.s of heavenly bodies are those which lie outside the solar system. Every one of those glittering points we see on a starlit night is at an immensely greater distance from us than is any member of the Solar System. Yet the members of this little colony of ours, judged by terrestrial standards, are at enormous distances from one another. If a sh.e.l.l were shot in a straight line from one side of Neptune's...o...b..t to the other it would take five hundred years to complete its journey. Yet this distance, the greatest in the Solar System as now known (excepting the far swing of some of the comets), is insignificant compared to the distances of the stars. One of the nearest stars to the earth that we know of is Alpha Centauri, estimated to be some twenty-five million millions of miles away. Sirius, the brightest star in the firmament, is double this distance from the earth.

We must imagine the colony of planets to which we belong as a compact little family swimming in an immense void. At distances which would take our sh.e.l.l, not hundreds, but millions of years to traverse, we reach the stars--or rather, a star, for the distances between stars are as great as the distance between the nearest of them and our Sun. The Earth, the planet on which we live, is a mighty globe bounded by a crust of rock many miles in thickness; the great volumes of water which we call our oceans lie in the deeper hollows of the crust. Above the surface an ocean of invisible gas, the atmosphere, rises to a height of about three hundred miles, getting thinner and thinner as it ascends.

[Ill.u.s.tration: LAPLACE.

One of the greatest mathematical astronomers of all time and the originator of the nebular theory.]

[Ill.u.s.tration: Photo: Royal Astronomical Society.

PROFESSOR J. C. ADAMS.

who, antic.i.p.ating the great French mathematician, Le Verrier, discovered the planet Neptune by calculations based on the irregularities of the orbit of Ura.n.u.s. One of the most dramatic discoveries in the history of Science.]

[Ill.u.s.tration: Photo: Elliott & Fry, Ltd.

PROFESSOR EDDINGTON.

Professor of Astronomy at Cambridge. The most famous of the English disciples of Einstein.]

[Ill.u.s.tration: FIG. 1.--DIAGRAMS OF THE SOLAR SYSTEM.

THE COMPARATIVE DISTANCES OF THE PLANETS.

(Drawn approximately to scale).

The isolation of the Solar System is very great. On the above scale the nearest star (at a distance of 25 trillions of miles) would be over one half mile away. The hours, days, and years are the measures of time as we use them; that is: Jupiter's ”Day” (one rotation of the planet) is made in ten of our hours; Mercury's ”Year” (one revolution of the planet around the Sun) is eighty-eight of our days. Mercury's ”Day” and ”Year” are the same. This planet turns always the same side to the Sun.]

[Ill.u.s.tration: THE COMPARATIVE SIZES OF THE SUN AND THE PLANETS (Drawn approximately to scale) On this scale the Sun would be 17-1/2 inches in diameter; it is far greater than all the planets put together. Jupiter, in turn, is greater than all the other planets put together.]

Except when the winds rise to a high speed, we seem to live in a very tranquil world. At night, when the glare of the sun pa.s.ses out of our atmosphere, the stars and planets seem to move across the heavens with a stately and solemn slowness. It was one of the first discoveries of modern astronomy that this movement is only apparent. The apparent creeping of the stars across the heavens at night is accounted for by the fact that the earth turns upon its axis once in every twenty-four hours. When we remember the size of the earth we see that this implies a prodigious speed.

In addition to this the earth revolves round the sun at a speed of more than a thousand miles a minute. Its path round the sun, year in year out, measures about 580,000,000 miles. The earth is held closely to this path by the gravitational pull of the sun, which has a ma.s.s 333,432 times that of the earth. If at any moment the sun ceased to exert this pull the earth would instantly fly off into s.p.a.ce straight in the direction in which it was moving at the time, that is to say, at a tangent. This tendency to fly off at a tangent is continuous. It is the balance between it and the sun's pull which keeps the earth to her almost circular orbit. In the same way the seven other planets are held to their orbits.

Circling round the earth, in the same way as the earth circles round the sun, is our moon. Sometimes the moon pa.s.ses directly between us and the sun, and cuts off the light from us. We then have a total or partial eclipse of the sun. At other times the earth pa.s.ses directly between the sun and the moon, and causes an eclipse of the moon. The great ball of the earth naturally trails a mighty shadow across s.p.a.ce, and the moon is ”eclipsed” when it pa.s.ses into this.

The other seven planets, five of which have moons of their own, circle round the sun as the earth does. The sun's ma.s.s is immensely larger than that of all the planets put together, and all of them would be drawn into it and perish if they did not travel rapidly round it in gigantic orbits. So the eight planets, spinning round on their axes, follow their fixed paths round the sun. The planets are secondary bodies, but they are most important, because they are the only globes in which there can be life, as we know life.

If we could be transported in some magical way to an immense distance in s.p.a.ce above the sun, we should see our Solar System as it is drawn in the accompanying diagram (Fig. 1), except that the planets would be mere specks, faintly visible in the light which they receive from the sun. (This diagram is drawn approximately to scale.) If we moved still farther away, trillions of miles away, the planets would fade entirely out of view, and the sun would shrink into a point of fire, a star. And here you begin to realize the nature of the universe. The sun is a star. The stars are suns. Our sun looks big simply because of its comparative nearness to us. The universe is a stupendous collection of millions of stars or suns, many of which may have planetary families like ours.

-- 2.

The Scale of the Universe.