E=mc2

The most famous equation ever written. But do you really know what it means?

E=mc2 is really important, and almost everyone knows it. But almost no one knows what it really means. Heaps and heaps of books try and try again to explain it. But as author David Bodanis says, "Who can understand that stuff?"

1905 seems a very long time ago but actually some of the things that happen today are very similar to things that happened back then. The old folks are still grumpy at younger folks because they are disrespecting them.

In 1905, it took just thirty-five days for Einstein to write a rough copy of thirty-eight pages of his theory of relativity. Four paragraphs from the end of the supplement, Einstein wrote it: E=mc2.

E is for Energy

In the late summer of 1821, Michael Faraday, an apprentice bookbinder, started working on the relationship between electricity and magnets. He propped up a magnet and dangled a wire above it. He then imagined that there were invisible circular lines circling around the magnet, and if he was right the wire should begin to move around in circles. Faraday had thought up the basis of the electric engine. He also discovered that different kinds of energy were linked.

M is for Mass

The things that fill our universe can be squashed, hammered, squeezed or chopped to bits but they will still not disappear.

In the 1980s Einstein proved his teachers very wrong on the topic that energy and mass were two completely different things.

C is for the Speed of Light

The "C" for the "speed of light" means "Celeritas." "Celeritas" meaning "swift" in Latin.

One of the moons of Jupiter called Io was meant to move around Jupiter every 42.5 hours, but it never did. It was always going a little faster or a little slower. Roemer, (a 21 year old astrologer) found out that it was not how Io was travelling but it was how Earth was travelling. For example in summer Io would be closer to us so we would see Io sooner, but in the winter of that same year Io would be farther away from us so we would not see Io that soon.

The speed that Roemer estimated for the speed of light was quite close to the current estimate of 670,000,000 mph.

Mach 1 is the speed of sound, about 700-mph. A 747 jet travels at just a little under Mach 1. A Space Shuttle travels at Mach 25. The speed of light is Mach 900,000.

Light only exists if there is a moving light wave.

What E=mc2 Really Means.

E=mc2 is about changing a substance of any quantity into pure energy so the greater the mass that is being changed the more powerful the energy becomes. Small bombs have enough power to destroy many things. Einstein�s theory has helped many things like lasers, computer chips and medicines along. But these took many years to achieve because finding out how to transform energy was the trick. Radium and uranium, because of their endless supply of energy, were the start to finding the trick.

The Future

Einstein worried that his theory would lead to the construction of atomic bombs. This happened when the Manhattan Project was started during the war with Nazi Germany. In 1945 there was a bomb that exploded over Hiroshima. The light from that bomb reached the orbit of the moon.

Biography: October 22nd Sunday magazine.