If a child wants proof, we can think of 10 different ways to show that we are surrounded by air, but we are, of course, normally unaware that we live at the bottom of an 'ocean" of air. It is claimed, in this book, that we are unaware, similarly, that we are surrounded by an atmosphere of aether. There is one major difference, however: We have not been able to detect the aether. Nevertheless, the aether provides a solution to the following mystery: How can light, or any electromagnetic wave, travel for billions of years across the vastness of the Universe, without losing any energy? The answer is that the Universe is filled with a light-transmitting medium, The Aether. The proof that there is an aether is the subject of the present book.