The Theory of Everything

CERN

Even particles leave tracks in the BEBC (Big European Bubble Chamber)

Superstrings and the 10th Dimension

Superstring theory combines relativity and quantum in an elegant, intuitive way. First, it describes the myriad of quantum particles of nature because each particle represents a "note" on a vibrating string. Think of a violin string. No one says that A or B is more fundamental than C. What is fundamental is the string itself.

Superstring theory says that, if we had a supermicroscope and could peer at an electron, we would see a string vibrating in a certain mode. The string is extremely small (10 to the minus 33 centimeters!) so that the electron looks like a point particle to us. If we shake the string, so it vibrates in a different mode, then the electron can turn into something else, such as a quark, the fundamental constitute of protons and neutrons. Shake it again, and the string could vibrate in the mode which describes photons (the quanta of light). Shake it again and it turns into a graviton (the quanta of gravity).

In fact, the collective set of vibrations corresponds to the entire spectrum of known particles. Instead of postulating millions of different particles, one only has to postulate a single object, the superstring. The sub-atomic particles are notes on the superstring. Our bodies are symphonies of strings, and the laws of physics are the laws of harmony of the superstring.

The superstring theory can also explain gravity. When the superstring moves in space and time, splitting and rejoining into other strings, it forces the space-time surrounding it to curl up, just as Einstein's equations predict. In other words, even if Einstein never dreamed up general relativity, we might have discovered it through superstring theory.

CERN

Dimensions in the quantum world: the decay of a kaon leaves tracks behind it

Hyperspace

Superstring theory, of course, has its detractors. Many point out it predicts the universe is defined in 10 dimensional hyperspace, which sounds more like science fiction than real physics. It's indisputable that the universe exists in four dimensions (3 spatial dimensions and one time dimension). Every object in the universe, from the tip of your nose to the farthest star, can be located by giving just 3 co-ordinates (length, width, and height). If we also give the time, then we can describe every event in the universe with just four numbers. For example in New York, we might say to a friend, "meet me at 42nd street and 5th avenue, on the 25th floor, at 12:00." Thus, four numbers (42,5,25,12) completely specifies this event in space-time.