so basically the reason why we cannot see the other side of the moon is that the moon takes 28 days to spin on its axis and it takes 28 days to make a revolution around the earth, thus we only see one side.

it also seems like i may have misworded my question. the word dark is being stresssed too much. i guess what i meant was why can't we see the other side of the moon? i used the "dark side" of the moon as a reference to what is more popularly known.