Mass-energy equivalence is a principle in physics that suggests that mass and energy are interchangeable, and they are two forms of the same entity. This concept is famously encapsulated in Albert Einstein's equation: \[ E = mc^2 \] In this equation: - \( E \) is the energy, - \( m \) is the mass, - \( c \) is the speed of light in a vacuum (approximately \( 3 \times 10^8 \) meters per second).