Because the universe is not a definite quantity.
Ω
It is impossible to conceive of a limit to the extension of matter. Limitless space, the inexhaustible source of the transformation of potential energy into visible motion, and thence into heat and other forces, confronts us, and not a simple, finished piece of mechanism, running like a clock and stopping forever.
The future of the universe is its past. If the universe were to have had an end, this end would have been reached long ago, and we should not be here to study this problem.
It is because our conceptions are finite, that things have a beginning and an end. We cannot conceive of an absolutely endless series of transformations, either in the future or in the past, nor that an equally endless series of material combinations, of planets, suns, sun-systems, milky ways, stellar universes, can succeed each other. Nevertheless, the heavens are there to show us the infinite. Nor can we comprehend any better the infinity of space or of time; yet it is impossible for us to conceive of a limit to either, for our thought overleaps the limit, and is impotent to conceive of bounds beyond which there is no space nor time. One may travel forever, in any direction, without reaching a boundary, and as soon as anyone affirms that at a certain moment duration ceases, we refuse our assent; for we cannot confound time with the human measures of it.
These measures are relative and arbitrary; but time itself exists, like space, independently of them. Suppress everything, space and time would still remain; that is to say, space which material things may occupy, and the possibility of the succession of events. If this were not so, neither space nor time would be really measurable, not even in thought, since thought would not exist. But it is impossible for the mind even to suppress either the one or the other. Strictly speaking, it is neither space nor time that we are speaking of, but infinity and eternity, relative to which every measure, however great, is but a point.
We do not comprehend or conceive of infinite space or time, because we are incapable of it. But this incapacity does not invalidate the existence of the absolute. In confessing that we do not comprehend infinity, we feel it about us, and that space, as bounded by a wall or any barrier whatever, is in itself an absurd idea. And we are equally incapable of denying the possibility of the existence, at some instant of time, of a system of worlds whose motions would measure time without creating it. Do our clocks create time? No, they do but measure it. In the presence of the absolute, our measures of both time and space vanish; but the absolute remains.
We live, then, in the infinite, without doubting it for an instant. The hand which holds this pen is composed of eternal and indestructible elements, and the atoms which constituted it existed in the solar nebula whence our planet came, and will exist forever. Your lungs breathe, your brains think, with matter and forces which acted millions of years ago and will act endlessly. And the little globule which we inhabit floats, not at the center of a limited universe, but in the depth of infinity, as truly as does the most distant star which the telescope can discover.
The best definition of the universe ever given, to which there was nothing to add, is Pascal’s, “A sphere whose center is everywhere and circumference nowhere.”