SPACE
We have seen that our very thoughts, and therefore consciousness of living, are limited by Time and Space, but we cannot with the utmost endeavour conceive a limit to Time and Space; they are two twin sisters, alike in many respects but different in others, and we shall realise later on that they are readily interchangeable. The sensuous aspect of Motion is, as we have seen, the time that an object takes to go over a certain space—namely, what is called the rate at which it passes from one point to another, and we cannot imagine Motion unless it contains both of these modes in however small a quantity; we may have the greatest imaginable space traversed in a moment of time, or the smallest imaginable space covered in what may be called, for want of a better word, an eternity, but we still have to postulate what we call Motion; this, of course, follows from the fact that our thoughts require both these modes for forming concepts. If we compare our conception of Matter with that of Time and Space, we see that the two latter are not separately the object of any sense, but are the modes or conditions under which all our senses act, to a greater or less degree, and these conditions cannot therefore carry the same impression of objectivity to our senses as Matter does, except perhaps in the sense that all physical phenomena are simply motion, and motion is the product of both of these limitations but not of either of them separately.
If we analyse our conceptions of Time and Space we seem forced to postulate that they are both infinitely divisible and infinitely extensible; they are both what is called continuous and not discrete, we cannot conceive any minimum in their division; both duration in Time and extension in Space can be reduced, as it were, to a mathematical point; nor can we conceive any maximum in either duration or extension. They are both therefore comprised in every conception possible to our consciousness; all parts of Time are time and all parts of Space are space; there are no holes, as it were, in Space which are not space, nor intervals in Time which are not time, they are both complete units; Space cannot be limited except by space, and Time cannot be limited except by time. So far they are alike, but, on the other hand, Space is comprised of three dimensions—namely, length, breadth, and depth, whereas Time has the appearance to us of comprising one dimension only—namely, length.
Under our present conditions we can only think of one finite subject at a time, and, at that moment, all other subjects are cancelled. We can therefore only think of points in Time and Space as situated beyond, or in front of, other fixed points, which again must be followed by other points; we cannot fix a point in either so as to exclude the thought of a point beyond; we can only in fact examine them in a form of finite sequences.
The Idea of Infinity, which we shall refer to in a later View and show to be a false conception, is therefore a necessary result of the limitation of our thoughts; our physical Ego cannot conceive beyond the Finite as long as we are conscious of living under present conditions. With every act of perception by our senses, we have therefore not only intuition of the Visible or Finite, but we become at the same moment aware of an Invisible Infinite beyond. Time appears to us as an inconceivable, intangible something, which gives us the impression of movement without anything that moves it. Space is an omnipresent, intangible, inconceivable nothing, outside of which nothing which has existence can be even thought to exist. Let us now try and get an insight into what we mean by perception of distance in space.
The appreciation of distance depends upon what is called parallax, or the apparent displacement of projectment of an object when seen by our two eyes separately. If you hold up a finger and look at it, with each eye separately, you will see that the finger is projected by each eye on to a different part of the background; the angle which the lines of sight, from each eye, make when they meet at the object, is called the angle of parallax, and the further the object is away the smaller that angle becomes; it is, in fact, the angle subtended, at the object, by the distance between the two eyes. As the object is brought nearer the eyes have to be inclined inwards to impinge on that object; the appreciation of distance then, in our sense of sight, is dependent upon our perception of the amount of inclination of those two lines of sight, and is therefore an acquired knowledge. The distance between the eyes is about 2-1/2 inches, and this is a very short base line upon which to estimate distance; in fact, without the help of perspective and known dimensions of surrounding objects, it is doubtful if anyone could by its means estimate distance beyond a few hundred yards. The object would, of course, also have to be an unknown one, as, otherwise, the converse of the above comes into play, and the distance could be estimated by the angle which the known diameter of the object subtends at the eye; but this necessitates the size of the object being known beforehand and the employment of perspective.
We can extend our perception of distances by, ourselves, moving from one place to another, gaining thereby a longer base line, and noting the displacement of projection of the object on a distant background; by that means, distance up to several miles can probably be appreciated. But, when we try to determine the distance of, say, the Moon (240,000 miles away), we are helpless, especially as we have no marked background, except in the case of occultations of the Sun or Stars. But the Astronomer at once comes to our aid; a distance of several miles is carefully measured on a level plane, and, by placing telescopes at the extremities of that known line, we can mark the inclination of those telescopes to each other when focussed upon a particular mountain peak on the moon; by this means we know the angle of parallax (180° less the sum of the two angles of inclination), and, from this and our known length of base line, we can calculate the distance. When however we go a step further and attempt to calculate the distance of the Sun (93,000,000 miles), we find our last base line again absolutely inadequate. But the astronomer helps us again; we now separate our two telescopic eyes by the whole diameter of the earth (7900 miles); this is accomplished by taking from the Equator two simultaneous observations of the Sun, at its rising and setting; for when the Sun is setting, at say the Equinox, it is at that moment rising at exactly the other side of the earth; the inclination of the two telescopes, directed to a certain point on the Sun, will now give the distance approximately, though even this base line is too short for exactitude. When however we attempt to go still further and try to ascertain the distance of stars, which are a million times further off than the Sun, such a base line is quite out of the question. How then can we get a base line for our telescopes longer than the whole width of the earth? The Astronomer again provides the means. The earth takes one year to complete its vast orbit round the sun, and the diameter of that path is 186,000,000 miles. This is made our new base line for separating our telescopes; an observation of a star is taken, say, to-day, and after waiting six months, to enable the earth to reach the other extremity of its vast orbit, another observation is taken, and yet it is found, as we shall see later on, that the distance of the nearest fixed star is so stupendous that even this base line, of 186,000,000 miles, shows absolutely no inclination between the two telescopes except in about a dozen cases, and even in those the angle of parallax, perceivable, is so minute that no reliable distance can be calculated; we can only say that the star is at least as far away as a certain distance, but it may be much farther.
Let us now try by other means to get a clearer insight into the subject of this View, by tracing Space to the utmost limit of human conception. I think the best method I can adopt will be to take you, in imagination, for a journey as far as is possible by means of the best instruments at our disposal.
We will start outwards from the Sun, and glance on our way at the worlds involved in the Solar System. Let us first understand what are the dimensions of our central Luminary. The distance of the Moon from the Earth is 240,000 miles, but the dimensions of the Sun are so great that, were the centre of the Sun placed where the centre of the Earth is, the surface of the Sun would not only extend as far as the Moon, but as far again on the other side, and that would give the radius only of the enormous circumference of the Sun; another way to understand its size is, to remember that, light travelling 186,000 miles per second, would actually take five seconds to go across its disc. Let us now start outward from this vast mass. The first world we meet is the little planet Mercury, only 3000 miles in diameter, revolving round the Sun at a distance of 36 million miles. We next come upon Venus, at a distance of 67 million miles. She is only 400 miles smaller in diameter than our Earth, and, with the dense atmosphere with which she is surrounded, animal and vegetable life similar to that on our Earth would be possible. Continuing our course, we arrive at our Earth, situated 93 million miles away from the Sun. Still speeding on, a further 50 million miles brings us to Mars, with a diameter of nearly 5000 miles, and accompanied by two miniature moons. The sight of this planet in a good instrument is most interesting. Ocean beds and continents are visible, and the telescope shows large tracts of snow, though not necessarily formed from water (perhaps carbonic dioxide), surrounding its polar regions, which increase considerably during the winter, and decrease during the summer seasons on that planet; but there are no canals! The fact that our largest and best telescopes failed to show these imaginary canals, was an insurmountable barrier to the advocates of these markings, but the "Canalites" made their contention ridiculous when they actually suggested that the reason for this failure to perceive them was that our telescopes were too large to see such small markings! How such a statement could have been made is incomprehensible on any supposition, as everybody knows that the whole use of size, or what is called aperture, in a telescope, is to help us to see more clearly small and faint markings.
The distances we now have to travel become so great that I shall not attempt to give them; you can, however, form an idea of the tremendous spaces we are traversing when you consider that each successive planet is nearly double as far from the Sun as the preceding one.
In the place where, by Bode's law, we should expect to have found the next world, we find a group of small planets, ranging in size from about 200 miles in diameter down to only a few hundred yards. They pass through nearly the same point once in each of their periods of revolution round the Sun, and it has been suggested that they are fragments of a great globe rent asunder by some mighty catastrophe; over 400 of these little worlds have been discovered and have received names, or are known under certain numbers.
We now continue our voyage over the next huge space and arrive at Jupiter, the largest and grandest of the planets. This world is more than 1000 times larger than our Earth, its circumference being actually greater than the distance from the Earth to the Moon. It has seven moons, and its year is about twelve times as long as ours. Pursuing our journey, we next come to Saturn. It is nearly as large as Jupiter, and has a huge ring of planetary matter revolving round it in addition to seven moons. Further and further we go, and the planets behind us are disappearing, and even the Sun is dwindling down to a mere speck; still we hurry on, and at last alight on another planet, Uranus, about sixty times larger than our Earth; we see moons in attendance, but they have scarcely any light to reflect; the Sun is only a star now; but we must hasten on deeper and deeper into space. We shall again, as formerly, have to go nearly as far beyond the last planet as that planet is from the Sun. The mind cannot grasp these huge distances. Still we travel on to the last planet, Neptune, revolving on its lonely orbit; sunk so deep into space that, though it rushes round the Sun at the rate of 22,000 miles per hour, it takes 164 of our years to complete one revolution. Now let us look back from this remote point. What do we see? One planet only, Uranus, is visible to the unaided eye; the giant planets, Jupiter and Saturn, have disappeared, and the Sun itself is now only a star; practically no heat, no light, all is darkness in this solitary world; the Sun is 1000 times smaller than we see it from the earth, and gives, therefore, only one-thousandth part of its heat and light. Thus far have we gone, and, standing there at the enormous distance of 3,000,000,000 miles from our starting-point, we can begin to comprehend the vast limits of the solar system; we can begin to understand the ways of this mighty family of planets and satellites. But let us not set up too small a standard whereby to measure the Infinity of Space. We shall find, as we go on, that this stupendous system is but an infinitesimal part of the whole universe.
Let us now look forward along the path we are to take. We are standing on the outermost part of our Solar System, and there is no other planet towards which we can wing our flight; but all around are multitudes of stars, some shining with a brightness almost equal to what our Sun appears to give forth at that great distance, others hardly visible, but the smallest telescope increases their number enormously, and presents to our mind the appalling phantom of immensity in all its terror, standing there to withstand our next great step. How are we to continue on our journey when our very senses seem paralysed by this obstruction, and even imagination is powerless from utter loneliness? One guide only is there to help us, the messenger which flits from star to star, universe to universe; Light it is which will help us to appreciate even these bottomless depths. Now, Light travels 186,000 miles per second, or 12 million miles every minute of time. It therefore takes only about four hours to traverse the huge distance between our Sun and Neptune, where we are now supposed to be standing; but to leap across the space separating us from the nearest star, it would require many years for Light, travelling at 186,000 miles every second of that time, to span the distance. There are, in fact, only fifteen stars in the whole heaven that could be reached, on the wings of Light, in sixteen years!
Let us use this to continue our 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.