How many dimensions are there?

A special thanks to zandcruzher for this idea. Check out his fine stories.

When we think of dimensions, we normally think of three: length, width and height or X, Y and Z. Einstein added a fourth: time or T. However, the number of dimensions doesn’t stop there because according to physicists there are many more, and the number depends on who you talk to. What I mean by that is: it depends upon which theory you like--Superstring theory or M-theory. Superstring theory says that there are 10 dimensions, whereas M-theory says that there are 11. Why the difference? That would require a book to answer.

These higher dimensions are considered to be very compact and in extremely tiny spaces. They’re hidden from view and are curled up so tightly they can’t be measured or detected using current instruments. Another problem is that trying to visualize more than four dimensions will give one a headache. The math to describe them is very complicated. The physicists describe the extra six dimensions as existing in Calabi-Yau manifold space. What the heck is that? The answer is that it’s a type of K3 surface that uses six dimensions. See what I mean. This is very complex. A 2D image of a 6D Calabi-Yau manifold looks like a bad car wreck or an elaborate Christmas ornament. There is no easy way to visualize dimensions beyond four. It’s equivalent to a two dimensional person who is flat trying to visualize a third dimension. The only way to get an inkling of what more than four dimensions looks like is to take a slice of it, but even then it appears to be weird.

Superstring theory predicts the existence of strings as being the ultimate sub-particles. These strings can be open or closed and they vibrate at specific frequencies. This idea comes from the supersymmetry idea of particle physics, which states that for every boson (an integer spin particle) there is an associated fermion (a half-spin particle). In other words, particles are arranged in marriages with the boson being the male and the fermion being female. Superstring theory tries to reconcile all of the forces of nature (including gravity) into one underlying idea: strings. This is something that Einstein wanted to do but never succeeded.

In order for superstring theory to work it needs more than four dimensions. It has to do with the math, which is too complex to explain here. In any event the math predicts ten dimensions, or at least makes the theory valid.

M-theory, on the other hand, requires eleven dimensions in space. What M-theory does is consolidate all of the string theories into one unified theory. I guess they needed an extra dimension to do that because of trying to incorporate quantum gravity into the math. The main reason is the M-theory relies on G2 manifold, which is a seven-dimension space.

The main reason that these extra dimensions are needed is to make the math easier, and I use the word ‘easier’ in a satirical manner because the theoretical math for this subject is outrageously complicated. There is no proof that these extra dimensions actually exist. They’re all based on the math connected with these crazy quantum theories. This is why there is a lot of disagreement about what theory better describes all of the forces, including gravity. I don’t know if we’ll ever know which theory is correct or if some new theory will come along. That’s the way it is with theoretical physics; theories abound because there is no proof other than a mathematical one. The math and the labels they apply to concepts in these theories are just too darn complicated to comprehend, unless you’re a theoretical physicist, that is.

Thanks for reading.