Antimatter is not just in the realm of science fiction and Star Trek. It exists, and has been measured. But what is antimatter?
Antimatter is simply a substance that has some opposite qualities of regular matter.
To explain this more fully, atoms make up everything we see. Just as water is made of hydrogen and oxygen atoms, so it is with every other substance. The atoms, in turn, are made up of electrons, protons, and neutrons. Electrons each have a single negative charge, protons have a single positive charge, and neutrons have no charge at all.
The first antimatter particle discovered was the positron, or anti-electron. It has exactly the same mass as an electron, but it has a single positive charge. Using particle accelerators that slam particles together at near light speeds scientists produced the first observed anti-proton, though it lasted far less than a second. It had the same mass as a proton, but had a single negative charge.
Anti-neutrons have also been observed, but since they have no charge, it isn't the difference in charge that distinguishes the particle. Instead, it is the spin that makes it an anti-neutron. All neutrons possess a certain spin. Anti-neutrons, while having the same mass, have an opposite spin.
An interesting aspect of antimatter is that in contact with identical matter, there is a total inhalation of both. In essence, they cancel each other out. So an electron making contact with a positron will destroy both the electron and the positron, releasing a great deal of energy. To understand how this is possible, we need to look at Einstein's law of relativity.
Before doing that, we should look at Isaac Newton's law of Conservation of Energy. This states that energy can neither be created nor destroyed, it can only be altered.
Einstein's law went a step further, and tells us that matter and energy are the same, they are just different sides of the same coin. By this law, energy is equal to mass times the speed of light, squared. That number is enormous, and it is the basis of atomic power, as we know it today. The thing is that atomic power is less than 20% efficient, meaning that most of the power created can't be used. For comparison, though, a light bulb is less than 1% efficient, most of the excess being converted to heat. (The same is true in a nuclear reactor.)
However, since matter and antimatter totally destroy one another on contact, there is 100% efficiency. Put in another way, if we could figure out how to combine 1 gram of water and 1 gram of anti-water, and harness all the resultant energy, we could produce enough energy in that one exchange to power the electrical needs of this planet for the next thousand years!
Science is working feverishly to try to figure out a way to do this. The obstacles are many and great, such as how to create the anti-water to begin with, and how to contain it without causing a detonation prematurely. Still, the rewards are clearly worth the effort.
In any event, antimatter is a fascinating substance that is nowhere near being fiction. We know it exists, and probably in great quantities naturally. The question is; so now what?