ABSTRACT
So far in this book we have been concerned mainly with the discrete components that go to make up the universe as a whole, only briefly mentioning the large-scale aspects of this totality of all things. The problems with which we shall now be associated are inevitably quite different in many respects from those previously considered and it is for this reason that the overall study of the universe — its dimensions, age, evolution and particularly its origin and future characteristics — has been given a special name to distinguish it from the other, somewhat narrower, concepts of astronomy. We call this particular branch of the science cosmology. Until recently, though some of the best scientific minds of the past two centuries have contributed to its better understanding, cosmology was more of a speculative than an exact science, for astronomers were working with a paucity of data. All of this is now changing rapidly. Like all other branches of science, cosmology is based upon observational or experimental data and since, as we shall see, it bears a somewhat closer relationship to physics than to astronomy, it must also obey the known physical laws. Any speculations we may make concerning the universe as a whole, therefore, should be verifiable in the physics laboratory.
