Albert Einstein 60th anniversary: What does his most famous equation actually mean?

It is 60 years the great scientist Albert Einstein died but despite this his legend lives on.

Widely regarded as the most famous scientist ever, Einstein’s name is synonymous with problem solving and genius-like intellect.

With his shock of white hair and bushy moustache, he is instantly recognisable, but for all this it is one small equation that has ensured his legacy lives on.

In 1905, the German published his now famous theory of special relativity – E=mc2.

It is an equation that is known all around the world and one that adorns posters, t-shirts and has even been turned into tattoos.

But what is it and how does it help us today?



Put simply, the equation states that energy ‘stored’ in any object is equal to that object’s mass, multiplied by the speed of light squared.

The theory, which was revolutionary at the time, proposes that mass and energy are equivalent to each other and that atoms have massive amounts of energy stored up in them.

Each of the letters in the equation stands for a particular physical quantity.

The E is for the energy, measured in joules, the M is for the mass, measured in kilograms, and the C is for the speed of light – which is squared, i.e. multiplied by itself.

Before Einstein’s theory, scientists defined energy as the ‘stuff’ that allows objects to move or interact in some way.

For example, kinetic energy is associated with movement and thermal energy with heating.
After Einstein’s theory, mass was accepted as a new type of energy rather than just a measure of how much of the ‘stuff’ there was.

It also changed how scientists viewed the universe, with mass now being thought of in completely different terms.

E=mc2 meant that the mass of something became a new way to measure the total amount of energy present in an object – essentially, it allowed us to find ways of getting more energy.

This has best been shown, and to devastating effect, by the nuclear bomb - perhaps the reason why the equation has remained so famous.

It appeared in a US Government report by physicist Henry DeWolf Smyth on how preparations for creating an atomic bomb were going.

These days it is still used in nuclear power plants, working out how much energy can be got from an atoms mass through nuclear fission.
Electricity is then generated by this reaction boiling water, which in turn drives turbine generators.


Credit: Daily Mirror