Science and the Infinite, Sydney T. Klein [well read books TXT] 📗

voyage. On a clear night the human eye can perceive thousands of stars, in all directions, scattered without any apparent order or design; but in one locality, forming a huge ring round the heavens, there is a misty zone called the Milky Way. Let us turn a telescope with a low aperture on this, and what a sight presents itself! Instead of mist, myriads of stars are now seen surrounded by nebulous haze. We put a higher aperture on, and thus pierce further and further into space; the haze is resolved into myriads more stars, and more haze comes up from the deep beyond, showing that the visual ray was not yet strong enough to fathom the mighty distance; but let the full aperture be applied and mark the result. Mist and haze have disappeared; the telescope has pierced right through the stupendous distance, and only the vast abyss of space, boundless and unfathomable, is seen beyond.

Let us pause here for a moment to think what we have done. Light, travelling with its enormous velocity, requires on an average considerably over ten years to traverse the distance between our Solar System and Stars of the first magnitude, but the dimensions of the Milky Way are built up on such a huge scale that to traverse the whole stratum would require us to pass about 500 stars, separated from each other by this same tremendous interval; 10,000 years may therefore be computed as the shortest time which light, travelling with its enormous velocity, would take to sweep across the whole cluster, it being borne in mind that the Solar System is supposed to be located not far from the centre of this great star cluster, and that the cluster comprises all stars visible arrayed in a flat zone, the edges of which, where the stratum is deepest, being the locality of the Milky Way.

Let us once more continue our journey. We have traversed a distance which even on the wings of light we could only accomplish in many thousands of years, and now stand on the outskirts of our great star cluster, in the same way, and I hope with the same aspirations, as when we paused the last time on the confines of our Solar System. Behind us are myriads of shining orbs, in such countless numbers that human thought cannot even suggest a limit, and yet each of these is a mighty globe like our Sun, the centre of a planetary system, dispensing light and heat under conditions similar to what we are accustomed to here. Let us, however, turn our face away from these clusterings of mighty suns, and look steadfastly forward into the unbroken darkness, and once more brace our nerves to face that terrible phantom—Immensity.

We require now the most powerful instruments that science can put into our hands, and by their aid we will again essay to make another stride towards the appreciation of our subject. In what, to the unaided eye, was unbroken darkness, the telescope now enables us to discern a number of luminous points of haze, and towards one of these we continue our journey. The myriads of suns in our great star cluster are soon being left far behind; they shrink together, resolve themselves into haze, until the once glorious universe of countless millions of suns has dwindled down to a mere point of light, almost invisible to the naked eye. But look forward: the luminous cloud to which we are urging our flight has expanded, until what, at one time, was a mere patch of brightness, has now swelled into a mighty star cluster; myriads of suns burst into sight—we have traversed a distance which even on the wings of light would take hundreds of thousands of years, and have reached the confines of another Milky Way as glorious and mighty as the one we have left; whose limits light would require 10,000 years to traverse; and yet, in whatever direction the telescope is placed, star clusters are to be seen strewn over the surface of the heavens.

Let us take now the utmost limit of telescopic power in all directions. Where are we after all but in the centre of a sphere whose circumference is 100,000 times as far from us as one of the nearest fixed stars, a distance that light would take over a million years to traverse, and beyond whose circuit, infinity, boundless infinity, still stretches unfathomed as ever? We have made a step, indeed, but perhaps only towards acquaintance with a new order of infinitesimals. Once the distances of our Solar System seemed almost infinite quantities; compare them with the intervals between the fixed stars, and they become no quantities at all. And now when the spaces between the stars are contrasted with the gulfs of dark spaces separating firmaments, they absolutely vanish away. Can the whole firmamental creation in its turn be nothing but a corner of some mightier scheme? But let us not go on to bewilderment: we have passed from planet to planet, star to star, universe to universe, and still infinite space extends for ever beyond our grasp. We have gone as far towards the infinite as our sight, aided by the most powerful telescope, can hope to go. Is there no way then by which we can continue our journey further towards the appreciation of this infinity? A few years ago we should probably have denied that it was possible for man to go further; but quite lately a new method of observation has been developed, and we will try and use this to continue our flight.

The reason why, to our sight, an object becomes apparently smaller and smaller as it is withdrawn from the eye, until it at last disappears entirely, is that the eye is a very imperfect instrument for viewing objects at a great distance; it can only form an image of an object when that object is near enough to subtend a certain angle, or, in popular language, to show itself a certain size—the rays of light must converge—in fact, the eye cannot single out and appreciate parallel rays: could it do this, objects would not appear to grow smaller as they are removed. A pencil might be removed to the Moon, 240,000 miles away, and would still appear to the eye the same size as it does here close to you; with perfect vision there would be no such thing as perspective, but, with our present conditions of sight, the result would be inconvenient. We should never be able to see, at one and the same time, anything larger than the pupil of our eye. The beauties of the landscape would be gone, and our dearest friends would pass us unheeded and unseen; everyday life would resolve itself into a task similar to that of attempting to read our newspaper every morning by means of a powerful microscope; we should commence by getting on to a big black blotch, and, after wandering about for half an hour, we might perhaps then begin to find out that we were looking at the little letter "e," but anything like reading would be quite out of the question. We may, therefore, with our limited aperture of sight, be thankful that our eyes have the imperfection of not appreciating parallel rays. But we will now consider how this imperfection may be remedied by science.

There are two different ways of doing this—viz., first, by increasing the amount of light received, by means of telescopes of great aperture; and secondly, by employing an artificial retina a thousand times more sensitive than the human. Now, the human retina receives the impression of what it looks at in a very minute fraction of a second, provided of course that the eye is properly focussed, and no further impression will be made by keeping the eye fixed on that object; but in celestial photography, when the telescope is turned into a camera, the sensitive plate, having received the impression in the first second, may be exposed not only for many seconds, or minutes, or hours, but for an aggregate of even days by re-exposure, every second of which time details on that plate new objects, sunk so deep in the vast depths of space as to be immeasurably beyond the power of the human eye, even through telescopes hundreds of times more powerful than the largest instruments that science has enabled us to construct; and yet here is laid before us a faithful chart, by means of which we may once more continue our journey through space. A short exposure will show us firmaments and nebulæ just outside the range of our greatest telescopes, and every additional second extends our vision by such vast increases of distances that the brain reels at the thought; and yet, as we have seen, exposures of these sensitive plates may be, and have been, made not only for seconds, but for thousands and even hundreds of thousands of seconds! And still there is no end, no end where the weary mind can rest and contemplate; the finite mind of man can only cry out that there is no limit. In spite of all its strivings and groping by aid of speculative philosophy, the finite cannot attain to the Infinite, nor get any nearer to where the mighty sea of time breaks in noiseless waves on the dim shore of eternity.

In this journey through space we have apparently exhausted our power of conception of the extension of this View. Although we have travelled in one direction only, our flight was applicable to every possible known direction outwards into the vast abyss of Infinite space. But there is another path, by which we can also travel with profit to our understanding of this subject, running in the opposite direction—namely, inwards. Just as the outward journey seemed to take us towards the appreciation of what our finite senses call the infinitely great, so does this other path appear to intend to infinity, in the opposite direction, leading us to appreciate what is called the infinitely small. We have already considered this direction in View One, under the heading of "Relativity," and by combining these two experiences, we may see still more clearly that our very conception of Space is one of the modes only under which motion or physical phenomena are presented to our consciousness.

VIEW SEVEN TIME

In the last View I referred to the mysteries of Time and Space as twin-sisters; they have, as we saw, many aspects in common, and are the two modes or conditions under which all our senses act and by which our thoughts are limited. We arbitrarily divide each of these two mysteries into two parts, which parts are separated from each other, in either case, by a point which has, apparently, as its centre, our very consciousness of living. In the case of Space we call this point the Here, and on one side of it, as we saw in our last View, we have extension towards the infinitely great, and, on the other, intension towards the infinitely small. In the case of Time we call the middle point the Now, and on one side of this we place the duration of Time towards the future, and, on the other, we place what we call the duration of Time towards the past. In the case of Space we have the here and the overthere, equivalent in Time to the present and the future, but, though Time and Space are, as it were, twin-sisters, upon whose combined action depends our very consciousness of living, we do not treat them both equally.

It is a remarkable fact that the human race on this particular world has, in some inexplicable