The Basics What do the E = mc
2
units mean?
Solving the Equation A simple walk-through of the equation
Deriving the Equation 1 Deriving E = mc
2
without calculus
Deriving the Equation 2 Deriving E = mc
2
using calculus (advanced)
Energy from Radioactive Decay What is radioactive decay?
Energy from Nuclear Fission Pulling atoms apart
Energy from Nuclear Fusion Squeezing atoms together

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.

Special Relativity in 15 Minutes A quick summary of Special Relativity
Time Dilation How time changes during very high speed travel
Time Dilation Calculator New! 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 New!
The Light Clock A theoretical proof of time dilation

Galileo’s Relativity The Galilean transformation co-ordinate equations
E = mc
2
& Relativity in the News 5 new particles detected - March 2017
FAQ Isn’t it just a theory?
Páginas en Español Pages in Spanish
Seiten auf Deutsch Pages in German
SI Units Explained:
The mole How many atoms are there in a diamond?
The ampere How many electrons are needed to make a cup of tea?
The metre How long does it take to walk around the Earth?
The candela How many candles are as bright as a light bulb?
The kilogram How much would you weigh on the Moon?
The kelvin How hot is a bolt of lightning?
The second Is a second always a second?
SI Derived Units Just what is a henry?

The Basics
What do the E = mc
2
units mean?
Solving the Equation
A simple walk-through of the equation
Deriving the Equation 1
Deriving E = mc
2
without calculus (easy)
Deriving the Equation 2
Deriving E = mc
2
using calculus (advanced)
Energy from Radioactive Decay
What is radioactive decay?
Energy from Nuclear Fission
Pulling atoms apart
Energy from Nuclear Fusion
Squeezing atoms together

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.

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
How they are mathematically linked
The Light Clock
A theoretical proof of time dilation

Galileo’s Relativity
The Galilean transformation co-ordinate equations
E = mc2 & Relativity in the News
5 new particles detected - March 2017 New!
FAQ
Isn’t it just a theory?
Páginas en Español
Pages in Spanish
Seiten auf Deutsch
Pages in German
SI Units Explained:
The mole
How many atoms are there in a diamond?
The ampere
Number of electrons for a cup of tea?
The metre
How long does it take to walk around the Earth?
The candela
How many candles are as bright as a light bulb?
The kilogram
How much would you weigh on the Moon?
The kelvin
How hot is a bolt of lightning?
The second
Is a second always a second?
SI Derived Units Just what is a henry?

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.