Some of the most important of these quantities are mass, time, length, force, energy, momentum, electric charge, electric field strength, entropy and wavelength. These quantities and the relations among them, which we call laws, have been found to serve in and to explain a wide range of phenomena such as occur in mechanics, heat, electricity, magnetism, light, atomic and nuclear physics and in such related subjects as engineering, biophysics, meteorology and geophysics. In addition, the subject of philosophy is profoundly influenced both by the methods and development of physics. The department also offers a variety of courses in astronomy.