Is there such thing as time travel? Do we really have the ability to travel to other dimensions?

If there was a chance that such possibilities existed, what would one have to acquire to be able to travel to these other dimensions? I've always believed in the existence of other dimensions, but it's always been unclear to me whether or not the life-forms in these other dimensions can actually see us, or make contact with us. Are they just replaying, like still frames of memories, or moments? Or, are these beings tangible. Maybe not to us... but I have to believe that, in some dimension, they could be touched.