Energy

The quantity energy (E) is sometimes described as the ability to perform work or to heat an object. The name is derived from the Greek word energeia (ἐνέργεια), meaning "being at work". The corresponding unit is joule (J).

Energy may manifest itself mechanically, electrically and thermally, but also (classically) as mass and (quantum mechanically) as photon.

History

The concept of energy was introduced by the English scientist Thomas Young (1773 – 1829), but the word itself goes back to the Greek philosopher Aristotle (384 BC – 322 BC).

Related quantities

• energy (electrical)
• energy (mass)
• energy (mechanical)
• energy (photon)
• energy (thermal)
• power