CHAPTER III. THE PRESENT PHYSICAL UNIVERSE, "The cloud-capp'd towers, the gorgeous palaces, Yea, all which it inherit, shall dissolve; And, like this insubstantial pageant, faded, Leave not a rack behind."-SHAKESPEARE, Tempest. "All worldly shapes shall melt in gloom, The sun himself must die Before this mortal shall assume His immortality."-CAMPBELL. 92. HAVING in the last chapter briefly indicated the nature of the proposition which we intend to bring forward, we must next study, as a preliminary to further discussion, what science tells us about the present physical universe: what are the general laws to which it is now subject; when and what must have been its beginning; when and what will be its inevitable end. We have been driven into becoming accustomed to the phrase, "the material universe," which is generally used in a sense absolutely identical with that which we have chosen as our title. We shall soon see that the term is a very inapt one, inasmuch as matter is (though it may sound paradoxical to say so) the less important half of the material of the physical universe. In the present chapter we shall still further restrict ourselves by omitting, as far as possible, any reference to life 69 (even in its lowest aspect), and we likewise defer to a future chapter our account of the more reasonable speculations which have been advanced with regard to the intimate structure of matter and ether. 93. It is only within the last thirty or forty years that there has gradually dawned upon the minds of scientific men the conviction that there is something besides matter or stuff in the physical universe, which has at least as much claim as matter to recognition as an objective reality, though, of course, far less directly obvious to our senses as such, and therefore much later in being detected. So long as men spoke of light, heat, electricity, etc., as imponderables, they merely avoided or put aside the difficulty. When they attempted to rank them as matter,-heat, for instance, as caloric,-they at once fell into errors, from which a closer scrutiny of experimental results would assuredly have saved them. The idea of substance or stuff as necessary to objective existence very naturally arises from ordinary observations on matter; and as there could be little doubt of the physical reality of heat, light, etc., these were in early times at once set down as matter. Fire, in fact (including, it is to be presumed, everything which involved either heat or flame, real or apparent), was in early times one of the four so-called elements. In those days the sun was supposed to be only a great fire; a lightning-flash, an aurora, or a comet, was merely a flame; in other words, the essence of all these was the element fire, or, as it was later called, caloric. The sun, except when he appeared as the spreader of pestilence, was the beneficent fire, as were also some of the planets; the lightning, the comet, even the moon and Saturn, were baleful fires. This endeavour to assign a substantive existence to every phenomenon is, of course, perfectly natural; but on that very account excessively likely to be wrong. Humanum est errare comes with quite as much heartfelt conviction of its truth from the lips of the honest Pagan as from those of the Christian believer; though perhaps its meaning may be considerably less extended in the former than in the latter case. 94. But, before discussing what is that something else besides stuff which has an objective though not a substantive existence, let us in the first place inquire into the grounds of our belief, that matter itself has a real existence external to us; that, in fact, the so-called evidence of our senses is not a mere delusion. Now, some extreme thinkers write as if they would persuade us that a species of hallucination affects with similar impressions every individual mind, so that, for instance, one man may usefully warn another about a pitfall on a dark road, and so save him from a catastrophe which might otherwise be caused by something which exists, if at all, in the mentor's mind only,- at all events not as yet in that of his pupil; though, if the warning be unheeded, or not given, there will presently be another mind in which the pitfall will certainly exist with startling vividness. But this is altogether repugnant to every conviction which experience (our only guide in such matters) enables us to form; and, in the shape in which we have put it, could hardly be held at all by any reasonable being. Now physical science furnishes us with the following among many other arguments in proof of the reality of the external universe:-Experience of the most varied kind consistently shows us that we cannot produce or destroy the smallest quantity of matter. Exer cise our greatest powers of imagination, do with it what we please, we cannot make our senses indicate to us an increase or diminution in a given quantity of what we call matter. We find it so far amenable to our control that we can alter its arrangement, form, density, state of aggregation, temperature, etc.; nay, by so approximating it to other matter as to produce a chemical combination, we may entirely transform its appearance and properties,—all but one: its mass or quantity is completely beyond our control. Measure it by what process we please, by the "muscular sense,' by weight, anyhow, there it is, altogether independent of us, laughing our efforts to scorn! Can this be a mere mental idea which the mind that conceived it (or, at all events, in some way received the conception of it) is unable to destroy? But there is one other argument on this point which must be mentioned. Not only do our own senses invariably indicate to us the impossibility of altering the quantity of matter, but the senses of all men alike point to the same quantity, quality, and collocation of matter in the earth and external to the earth. Whence this extraordinary agreement between the evidences of the senses in different men, when the minds are so different? Our conviction then of the objective reality of matter is based upon the experimental truth that we can neither increase nor diminish its quantity, in fact on what we may conveniently for our present purpose call the Conservation of Matter. 95. Here let us pause for a moment to compare together this view of matter and the definition of the laws of the universe, which we have already given. The laws of the universe we defined (Art. 54) to be the laws according to which the beings in the universe are trammelled by the Governor thereof as regards time, space, and sensation. Now, it may be asked, is this definition consistent with a belief in the objective reality of matter? We reply, that the two are in perfect accordance. We do not here intend to enter into any metaphysical discussion. It is enough for us to say that our practical working certainty of the reality of matter means, firstly, that it offers resistance to our imagination and our will, and, secondly, that in particular it offers absolute resistance to all attempts to change its quantity. We shall soon see that both properties belong to something else. 96. Returning from this digression let us therefore assume that the objective reality of the external universe has been proved, and that this reality is strongly impressed upon us in virtue of that principle which we have called the conservation of matter. But as soon as we grant this, we are obliged by our reason, however little our senses may incline us to it, or rather however much they may dispose us against it, to allow objective reality to whatever is found to be in the same sense conserved. (We have here italicised these four words for a reason which will afterwards appear.) This is a question which deserves and must get careful consideration. 97. In abstract dynamics several things are said and mathematically proved by deductions from experiment to be conserved, but one only of these in the strict sense in which we have spoken of the conservation of matter. We will examine them briefly, and our non-mathematical readers must pardon us if in this examination we make use of certain technical expressions belonging to the domain of mathematical physics. |