Sunday, December 30, 2007

FAQ 4 - Aren't there 11 dimensions?

4. Doesn't science (M Theory) say there are really 11 dimensions?
This question was asked a lot more during the first few months of this project, when it was launched back in the summer of 2006. It still comes up from time to time. M Theory says there are 11 dimensions, but one of those is time. This framework for discussion says that time can be enfolded back into the ten spatial dimensions, and that time for whatever dimension you are examining is the way you move from one state to another. For we three dimensional creatures, we think of time as being in the fourth dimension. A two-dimensional flatlander would think of time as being in the third dimension. In any case, time is only a limited way of viewing the full dimension that it resides in.

Time is a Direction
Hypercubes and Plato's Cave
Aren't There Really 11 Dimensions?

Likewise, some people wonder why this project doesn't spend time talking about Calabi-Yau manifolds. There are some important tie-ins with this project to concepts from string theory that are worthy of note: for instance, string theorists are saying our reality is created by the interaction of a seven-dimensional (D7) brane and a three-dimensional (D3) brane. The idea from the Imagining the Tenth Dimension project that the basic laws for our three dimensional reality are defined at the seventh dimension could be thought of as a way to tie this in. Likewise, the idea that the higher dimensions are curled up down at the planck length and therefore invisible to us ties in quite easily: our "line of time" is being constructed from the available probabilistic choices at the fifth dimension, one planck length at a time. This means that, like the flatlander on the mobius strip, our line of time is actually twisting and turning in the fifth dimension but we are unaware. Imagining that the higher dimensions could also have a shape that we see as a Calabi-Yau manifold is really not that big a stretch: a Calabi-Yau manifold is just another way of visualizing how are universe is enfolded within the extra dimensions. It should still be noted, though, that string theory is not the main focus of this project, and the math tools that string theorists use are inherently vastly more complex than the way of visualizing the higher dimensions that we are playing with here.

For more on this:
Flatlanders on a Line
How to Make a Universe
An Expanding 4D Sphere
Slice of Reality
The Holographic Universe
What's Around the Corner?