How many dimensions are there?

Somebody actually read my last blog. Then they sent me this amazing link: http://www.pbs.org/wgbh/nova/elegant/program.html which leads to about three hours of incredible science movies in which not only do scientists admit they don't know what causes gravity, they also admit they really don't even know how many dimensions there are.

The latest guess is 11. This is all part of "string theory" in which scientists propose that everything is made up of incredibly small strings of vibrating energy. This is a fairly new theory and a lot of scientists are playing around with the equations it engenders.

I am having a bit of difficulty imagining what 11 dimensions are like. Imagine that our world is contained on a flat movie screen. Just like a movie screen contains only up/down, left/right, yet it does not contain the third dimension forward/backward. Are you with me so far? We watch movies and they "look" three dimensional, yet are only two dimensional, so it might be easy to imagine our whole world stuck on the movie screen. Then suddenly, when some danger is impending, the actor steps FORWARD off the screen into our world of 3 dimensions. Okay, so it is hard to imagine, but suppose somebody in our three dimensional world could figure out some way to step out of our world into the fourth dimension.

This is the basis of some pretty amazing science fiction stories. Well, apparently, today's science fiction often becomes tomorrow's science fact. Now scientists are not just proposing a fourth dimension, but 8 more dimensions. Perhaps our whole galaxy (these scientists propose) are on a huge sheet or membrane that contains the three dimensions, and this "brane" is floating around somehow inside of the other 8 dimensions.

Oh wait a moment. Einstein proposed a fourth dimension--time. That is why we sometimes speak of the "space-time continuum." So the string theoreticians are only proposing an additional 7 dimensions.

Where are they? That is the tricky part. Our brains are locked in a three dimensional world (four if you consider time a dimension) and we can't visualize any more dimensions. There are some really advanced mathematics that describe these dimensions, but they are way beyond anthing I learned in college.

So far, the "string theory" is just a mathematical model -- a theory. Some people are hoping that the new super colliders that they are making might start to prove these theories. Go watch the movies at that link I gave above and see if YOU can figure it all out.

More dimensions stretch the brain
David A. Youngs