Attention All Nerds:

This is string theory, in the shortest and most simplistic manner possible.

In physics, there are four forces of nature; 1) strong nuclear force, 2) weak nuclear force, 3) electromagnetism, 4) gravity. Einstein's theory of general relativity explains gravity as a force that acts on the very largest objects in our universe (e.g. planets, stars, etc.). Quantum mechanics describe the other three forces that act on the very smallest objects in our universe (e.g. atoms, protons, electrons, etc.). When we attempt to combine general relativity and quantum mechanics (i.e. to describe the events in the universe under a single law), inconsistencies in both theories are conjured and the laws break down.

String theory attempts to describe all four forces of nature under a single law, and thus seeks to describe all events in the universe as a result of one complete set of physical properties. String theory suggests that there is a single unit of energy that makes up all things. An object is made of molecues; molecues are made of atoms; atoms are made of protons, neutrons, and electrons; protons and neutrons are made of quarks (currently the smallest known unit of matter); and at the heart of each quark is a proposed "string." This string is a vibrating, pulsating loop of energy that makes up all matter. The different ways this energy undulates determines whether the string will be an electron, a proton quark, or a neutron quark, etc. If we take into account this string (which cannot be seen or otherwise determined to even exist by today's scientific methods), the four forces of nature can be used to explain it's actions. In other words, the movement of strings obey both the theory of general relativity and quantum mechanics. Additionally, string theory proposes an additional six dimensions to our known four (three dimensions of space [left-right, front-back, up-down] and one of time [before-after]). These six dimensions exist at the level of the string in a spiral pattern that regulates how the energy of the string vibrates.

This doesn't seem like a lot, but for physicists this single theory means that everything from a radioactive decay, to friction, to a sneeze can be described with a single law. Of course, others (e.g. chaos theorists) argue that when equations become more complex (i.e. when you try to explain larger events in terms of the movements of tiny tiny strings inside atom particles), other independent law of physics must come into play. However, because no modern scientific test can be developed (with our present knowledge) to even determine the existence of strings, string theory remains on the border between science and philisophy.

For more info, watch "The Elegant Universe" on NOVA, PBS.

PS - My opinion: Why do you even need to explain EVERYTHING on just a single theory? Who says that the universe even runs on a single law? Why can't we just say that different things act differently because of different laws? Bah!

PSS - I apologize for this post. But you can blame Spencer, he asked.