posted on May, 20 2006 @ 07:56 AM
Well, I tend to pop up whenever there's some 4-d stuff being talked about, so here I am
The 4th dimension does exist, and in a sense can be measured. It is Space-Time (what Einstein was talking about in General Relativity).
When a moon falls into orbit around a planet, it's because the planet and the moon are creating slight imperfections (warps) in the space-time
continuum, which cause the moon and planet to be in a state of falling towards each other, but never getting there.
Think of it like this. Take a sheet of paper, and put it on a bowl. Now, take a marble and put it in the middle of this sheet of paper. See how the
sheet of paper sinks where the marble is? The marble's mass warps the fabric of the paper, and warps it's 2-dimensional space. If you were a
2-dimensional object travelling along the paper, and you tried to travel in a straight line beside the marble (which you see as a circle) you would
find yourself unexplainably starting to move around the marble. "Straight-forward" has somehow turned into a bend. Now, since paper is made of a
substance, not even the heaviest marble could bend the paper to cause a straight line to turn into a circle.
Now, if you take that example, shift the dimensions up by 1, you'll notice that you - as a 3-dimensional creature, on a 3-dimensional plane of
existance, cannot see the 4-dimensional warping of space-time. Things now appear to orbit each other, pulled towards each other. Really, the space is
warped in such a way that moving straight forward leads them in a big circle over and over again.