If you want to know... how images are stored on a compact disk, how a laser works, the composition of the DNA molecule, or whether the universe has a beginning or an end, then you want to study physics. Physics is the basic science that underlies astronomy, biology, chemistry, engineering, geology, and all the other applied sciences.
The subject matter of physics is the physical universe, and the primary reason for studying physics is to gain a unifying understanding of the world around us. This is accomplished through the interplay of experiment and theory that constitutes the scientific method. Beyond the purely intellectual pursuit of knowledge for its own sake, there is the vast use of discovered laws of nature for the purpose of improving our material well-being. Just look around you. Innovations like computers, high-definition television, nuclear power, lasers, communications satellites, ultrasonic scanners, recombinant DNA, magnetic resonance imaging in medicine, and high temperature superconductivity are revolutionizing the world in which we live. Physicists are at the very center of the expansion of knowledge and technology, and career opportunities have never been better!