Einstein's Equation, E = mc2
What does this famous and mysterious equation mean? We've all seen it, and yet a lot of us don't understand it or its implications.
Essentially, it states:
Energy = mass x c. ; c is the speed of light. This is an incredibly large number because light travels extremely quickly. Think about it: When you flick a light switch, light appears instantaneously. This is because light travels so fast from the light source to you that it seems to take no time at all. The actual speed of light is about 300,000 kilometers a second (186,000 miles/second). If you were in an airplane that traveled at the speed of light, you could completely circle the earth in less than a second. That's FAST!!
Now that we know what the equation means literally, what are its implications? Basically, it shows that energy is matter, and that they are interchangeable. Matter can be turned into energy, and energy can be turned into matter. This means that if a particle gains a lot of energy, it appears to have gained mass, because energy is mass. Thus, a particle's mass depends on its environment. If its environment is very hot (and thus has a lot of energy), it can gain mass in the form of gained energy. Additionally, if even a small amount of mass is converted to energy, a gargantuan amount of energy is still released. This is because the speed of light is so large a number. For instance, we can determine the amount of energy that composes one kilogram of mass by plugging the numbers into the equation using the speed of light in meters/second. The energy is measured in joules, which is the standard energy unit in the metric system.
Energy = 1 kg x (the speed of light in meters/second)2
Energy = 1 x 300,000,0002
Energy = 90,000,000,000,000,000 joules (a metric energy unit)
This is equivalent to 25,000,000,000 kWh (kiloWatt hours) of electricity, or 25 billion kWh. This is enough electricity to power 47,000 60-watt light bulbs for an entire year. Thus, it is quite easy to see that just one kilogram of matter is equivalent to an enormous amount of energy. However, it turns out that there is no practical way to convert mass completely into energy. At least, not yet.
This article is from:
http://library.thinkquest.org/17940/texts/atom2/atom2.html