Home > Encyclopedia of Science > Physics

• Classical and modern physics
• Words to Know
• Divisions of physics
• Interrelationship of physics to other sciences

Physics is the science that deals with matter and energy and with the interaction between them. Perhaps you would like to determine how best to aim a rifle in order to hit a target with a bullet. Or you want to know how to build a ship out of steel and make sure that it will float. Or you plan to design a house that can be heated just with sunlight. Physics can be used in answering any of these questions.

Physics is one of the oldest of the sciences. It is usually said to have begun with the work of Italian scientist Galileo Galilei (1564–1642) in the first half of the seventeenth century. Galileo laid down a number of basic...