Meh....
Go to
Popular Science Homepage | Popular Science they have a very good article to explain this, and it makes sense.
A definition of a brane is an object rests on another object with one more deminsion. The analogy goes something of the skin on your soup that arrises over a period of time. The two deminsional skin is resting on a three deminsional volume. Therefore a brane.
The brane theory says we are a three deminsional world resting on a fourth deminsion plane. This plane is time. Also through this grouling math, there comes to be about six more deminsions. The displacement of these deminsions create a six deminsion object that I can't pronounce, and even the people who came up with it have a hard time comprehending what the object would look like. It turns out you can cut this object into the fourth deminsion with another three deminsion figure inside it and a two deminsion plane.
So what do they conclue? That there are two branes, each a three demensional world resting in the fourth deminsion, and they are seperated from a two demensional object. So, there are parallel universes with a two demensional plane seperating the two. That is all I know, its pretty wack if you know what I mean.
And here is a really really wierd thing. The only thing that can travel between these deminsions (I just realized I keep on altering my spelling of demensions....too lazy to look it up) are gravitrons. The particles of gravity. That is why gravity is such a weak force relative to all the others. When an object is falling, some of the gravitrons are traveling between demensions. Therefore force is lost.
That introduces particle theory, and I don't want to go over that because it is off topic. You can easily google it up and find out about it. But keep in mind this theory goes againse relativity, and then a genius by the name Stephen Hawking came with an answer. I honestly think he should get more credit than Einstein, not saying Einstein is stupid or anything, but saying Hawking is that smart. Whatever, hope that helped.