Last updated: March 2, 2026

Einstein's Mass-Energy Equivalence

Formula

E = mc² is perhaps the most famous equation in physics. It shows that mass and energy are interchangeable, with the speed of light squared (c² ≈ 9 × 10¹⁶ m²/s²) as the conversion factor. Even a tiny amount of mass contains an enormous amount of energy, which is the principle behind nuclear power and nuclear weapons.

Common use cases:

  • Nuclear energy calculations
  • Particle physics mass-energy conversion
  • Understanding stellar energy output

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