Another major form of energy is nuclear energy, the energy that is trapped inside each atom. One of the laws of the universe is that matter and energy can't be created nor destroyed. But they can be changed in form.
Matter can be changed into energy. The world's most famous scientist, Albert Einstein, created the mathematical formula that explains this. It is:
This equation says:
E [energy] equals m [mass] times c2 [c stands for the velocity or the speed of light. c2 means c times c, or the speed of light raised to the second power — or c-squared.]
You can listen to Einstein's voice explaining this at:
Please note that some web browser software may not show an exponent (raising something to a power, a mathematical expression) on the Internet. Normally c-squared is shown with a smaller "2" placed above and to the right of the c.
Scientists used Einstein's famous equation as the key to unlock atomic energy and also create atomic bombs.
The ancient Greeks said the smallest part of nature is an atom. But they did not know 2,000 years ago about nature's even smaller parts.
As we learned in chapter 2, atoms are made up of smaller particles -- a nucleus of protons and neutrons, surrounded by electrons which swirl around the nucleus much like the earth revolves around the sun.
Read about Ocean Energy in the next chapter.