E = Mc² Easily Explained

You've heard the equation E = mc² many times. Here's the easy explanation.

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Matt Anderson's Take
It's probably the most famous equation on the planet, E = mc². You learned about it in school. You probably know that Albert Einstein came up with the equation and that it is derived from his Theory of Relativity. But, do you really know what it means? Follow along and we'll explain E = mc² in plain English.

The Equation


First, let's do the longhand version of E = mc² so you can see what each letter stands for:

E = Energy (measured in joules)
m = Mass (the weight in kilograms)
c = The speed of light (in meters per second, which gets squared)

So the equation is:

Energy = mass x the speed of light, squared

The Explanation

In its most basic terms, the equation describes the relationship of energy to matter and how energy and matter are two different forms of the same thing.

Energy
We know that energy cannot be created or destroyed but it can take on a different form.

Mass
Mass is basically the amount of matter in any given object. Most people think of mass as the weight of an object which isn't quite true. Weight is based on gravity so a 10 pound object here on Earth isn't going to weigh 10 pounds on the Moon. An object's mass is always the same regardless of gravity and can only change if the object is physically altered. Just like with energy, mass cannot be created or destroyed and can only change form.

Real World Examples


Take an energy source like propane that, when burned, can convert its potential energy into thermal energy which can then turn a generator to make electricity or heat your grill.

Remember earlier how we said that energy and mass are two different forms of the same thing? In our propane example we're showing how that mass (which is another form of energy) was turned into heat energy. Nothing was created or destroyed, simply transferred from one form of energy (the propane, or mass) into another (heat).

While this is certainly a very simplified explanation of E = mc², and things can get very complicated from here, I hope this give you a general understanding of Einstein's' world changing equation.
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Matt Anderson
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