History of Energy in Timeline

Energy is a fundamental quantitative property that can be transferred to a body or system, manifesting as work, heat, or light. A key principle is the law of conservation of energy, stating that energy transforms but is neither created nor destroyed. The standard unit for measuring energy in the International System of Units (SI) is the joule (J).

1900: Henri Poincaré's Mass-Energy Formulas

In 1900, Henri Poincaré derived mass-energy formulas.

1904: Friedrich Hasenöhrl's Mass-Energy Formulas

In 1904, Friedrich Hasenöhrl derived mass-energy formulas.

1905: Einstein's Mass-Energy Equivalence Formula

In 1905, Albert Einstein derived the formula E = mc², which quantifies the mass-energy equivalence between relativistic mass and energy within the concept of special relativity.

1905: Einstein's Theory of Special Relativity

In 1905, Albert Einstein's theory of special relativity showed that rest mass corresponds to an equivalent amount of rest energy, meaning rest mass can be converted to or from equivalent amounts of energy.

1913: Bohr Theory of the Atom

In 1913, the notion of quantized energy levels was proposed by Danish physicist Niels Bohr in the Bohr theory of the atom.

1918: Noether's Theorem

In 1918, Noether's theorem stated that any differentiable symmetry of the action of a physical system has a corresponding conservation law.

1918: Conservation of Energy and Noether's Theorem

In 1918, theorists understood that the law of conservation of energy is a direct mathematical consequence of the translational symmetry of the quantity conjugate to energy, namely time, according to Noether's theorem.

1926: Schrödinger and Heisenberg's Quantum Mechanical Theory

In 1926, Erwin Schrödinger and Werner Heisenberg advanced the modern quantum mechanical theory, using the Schrödinger equation to explain energy levels.