The purpose of these pages is to explain E = mc 2 in a clear, concise and understandable way with easily followed worked examples, and with further pages examining the Special Theory of Relativity in order to describe its background. Albert Einstein published his Special Theory of Relativity in 1905 and in doing so demonstrated that mass and energy are actually the same thing, with one a tightly compressed manifestation of the other. This mass-energy equivalence has had a major impact on all our lives, although how and why isn't always obvious. Although relativity has a reputation for being difficult much of it can be understood by anyone.

Try The Time Dilation Calculator and see how long it takes to reach the stars! Click me!

E = mc

2

The Basics What do the E = mc 2 units mean?

Solving the Equation A simple walk-through of the equation

Deriving the Equation Deriving E = mc 2 with simple working

E = mc 2 Calculator A quick and easy calculator

Energy from Radioactive Decay Atoms falling apart and releasing energy

Energy from Nuclear Fission Pulling atoms apart

Energy from Nuclear Fusion Squeezing atoms together

Special Relativity in 15 Minutes A quick summary of Special Relativity

Time Dilation How time changes during very high speed travel

Time Dilation Calculator How long does it take to reach the stars?

Time Dilation Worked Examples Solving the time dilation equation

Time Dilation at “Low” Speeds How is time affected when flying?

The Constant Speed of Light Light is very, very strange…

Speed, Frequency and Wavelength Explained, and a Calculator

The Light Clock A theoretical proof of time dilation

Special

Relativity

Pages

The Mole The Ampere The Metre The Candela The Kilogram The Kelvin The Second

New! Do photons have color? Click to Read

Galileo’s Relativity The Galilean transformation co-ordinate equations Einstein’s original papers - Special Relativity and E = mc 2 (in English) E = mc 2 & Relativity in the News Physics news (older pages: 1) Frequently Asked Questions Isn’t it just a theory? Do photons have color? Páginas en Español Pages in Spanish Seiten auf Deutsch Pages in German Fun page: Magic Particles - Can you work out how it’s done?

SI Units

How to Memorize Equations quickly and easily

E = mc2 Explained

NEW! Quick and Easy SuperFast Guides NEW!

Calculators: Each page contains a calculator for a given unit together with examples and rearrangements to make other units the subject:

[ Speed (m/s), distance (m) and time (s) ] [ Power (W), energy (J) and time (s) ] [ The newton (N) ] [ Density, mass and volume ] [ Force, mass and acceleration F = ma ]

[ Momentum (p), mass (m) and velocity (v) ] [Momentum, Newton and cannons ]

[ Newton’s Law of Gravity (F = G m1 m2 / r 2 ) ] [Gravity near the Earth’s surface: E = mgh, PE = mgh, U = mgh ]

More…

[ Special Relativity ] [ General Relativity ] [ Einstein ] [ Time Dilation ] [ Black Holes ] [ Twin Paradox ] [ Time Dilation Formula ]

Albert Einstein published his Special Theory of Relativity in 1905 and in doing so demonstrated that mass and energy are actually the same thing, with one a tightly compressed manifestation of the other. This mass- energy equivalence has had a major impact on all our lives, although how and why isn't always obvious. Although relativity has a reputation for being difficult much of it can be understood by anyone.

Galileo’s Relativity The Galilean transformations Einstein’s original papers - Special Relativity and E = mc 2 E = mc 2 & Relativity in the News Physics news (older: 1) Frequently Asked Questions: - Isn’t it just a theory? - Do photons have color? Páginas en Español Pages in Spanish Seiten auf Deutsch Pages in German Fun page: Magic Particles - Can you work out how it’s done?