Posted: Oct 05, 2011 7:04 pm
It means that everything in the universe is getting further apart, relatively speaking. It's kind of like bread dough with raisins or something in it. As it sits on the counter to rise the raisins get further apart. The size of the 'dough' doesn't matter- it could very well be infinite. (Whether or not the universe is infinite, and what that means for expansion is a fascinating subject that I won't go into right now, but trust me- it's pretty cool stuff)
Remember, you can't think about the universe in a normal three-dimensional way because it IS the normal three dimensions. Asking what it's expanding into, for example, is like asking what happens when you go south of the south pole.
Remember, you can't think about the universe in a normal three-dimensional way because it IS the normal three dimensions. Asking what it's expanding into, for example, is like asking what happens when you go south of the south pole.