Hey I’m Khalid and today with About.com we are going to define physics and discuss some of its principles and disciplines using lessons from the About.com guide site.Physics is the study of the motion of matter through space and time. In this study, concepts such as energy and force along with their effects on objects are examined and explained. The implications of physics and the laws that it outlines influence many other sciences and can be seen at work in our everyday lives.Physics originally grew out of philosophy, as people tried to further understand the world around them. One of the first people to develop physics as a science was Galileo Galilei, who’s work was later refined by Sir Isaac Newton. In 1687, Newton published “The Mathematical Principles of Natural Philosophy” which established the law of gravity as well as his three laws of motion that served as cornerstones of physics until Albert Einstein’s introduction of the Theory of Special Relativity in 1906.Physics can be broken down into two categories, classical and modern. The key difference between classical and modern physics is that classical physics can be roughly applied to object bigger than an atom but smaller than galaxies which move much slower than the speed of light, while modern physics deals with extreme conditions (very small particles and distances) and incorporates the work of quantum mechanics.Since the understanding of physics is fundamental to so many different applications, the science can be broken down into a number of special studies including electromagnetism, astronomy, mechanics, nuclear physics, thermodynamics, and quantum physics, plus many more. All of these studies however can be traced back to the simple study of the movement matter. So, even as the science and mathematics applied get increasingly complex, there are certain equations and laws that are understood by all physicists.Physics is at its root the study of how the world operates and by using the collected work and publication of the science, people can not only understand the world around them but can also explain the universe at large.Thanks for watching, for more information, please visit About.com.