Description: In very basic terms energy is defined as the capacity of a system to do some work. However, this definition does not capture the rich, multilayered aspect of energy, and its manifestation from the scale of fundamental particles to the entire Universe. One of the fundamental principles of physics is that total energy is always conserved. Energy takes various forms (e.g. kinetic, gravitational potential, thermal) depending on the context and can be converted from one form to another. Relativistic physics describes an innate connection between mass and energy. The unit of energy is the joule, and it quantifies the amount of work done on an object by a force of one newton moving it a distance of one meter. In particle physics, however, energy is expressed in electron volts.

Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".