How Things Looked One Hundred Years Ago
As scientific discoveries accumulated in the centuries leading up to our own, the expectations of the materialist seemed to be confirmed. There was no evidence that the universe had a beginning, and several discoveries seemed to indicate that it had always existed.
To begin with, in Newtonian physics, time was conceived of as a single dimension stretching without limit into both past and future, just as space was conceived of as an infinite three-dimensional volume stretching without limit in every direction. In Newtonian physics, it was natural to assume that time goes on forever just as numbers go on forever, from -∞ to +∞.
Later, “the principle of conservation of energy”—the First Law of Thermodynamics—was discovered. As we all learned it in school, “energy can never be created or destroyed, but only changed in form.” I vividly remember that when I was ten and had just learned this principle in school, I used it to argue against an older brother, that the universe did not have to be created because the energy in it could always have existed. Indeed, I argued, the law of conservation of energy says that this energy could not have been created. I suppose this was a clever argument for a ten-year-old. I certainly thought so at the time.
In the nineteenth century, chemists discovered the law of conservation of mass. In chemical reactions, the total mass of the reactants does not change—at least as far as could be measured back then. Therefore, not only energy but matter itself was both indestructible and uncreatable. Eventually, with the equivalence of mass and energy, which was discovered by Einstein, these two principles were subsumed into a single principle. No violation of this principle has ever been observed.
To all appearances, therefore, both the world of space and time, and all the matter and energy in it, had always existed and always would. To say that time had a beginning, while not absolutely ruled out, would have seemed very strange from the viewpoint of nineteenth-century physics. It would have been as strange as saying that space did not go on forever but had edges to it somewhere. At that time, there was no hint of the “beginning” in which religious people believed. The materialists’ expectations seemed to have been borne out. As we shall see, however, the picture changed in quite a dramatic and unexpected way as a result of Einstein’s Theory of General Relativity.