Mass-Energy Equivalence:This principle, famously expressed by Einstein's equation E=mc², states that mass and energy are interchangeable and equivalent.
Photon:A photon is a particle of light that carries energy. It is considered a quantum of electromagnetic radiation.
Conservation Laws: Conservation laws state that certain properties, such as energy or momentum, remain constant within an isolated system unless acted upon by external forces. They play a crucial role in understanding energy in modern physics.