Okay so before i start off here, I would like to point out right off the bat that I will do my best to keep this as un-biased as possible as far as religious standpoints. This theory perfectly merges beliefs of christianity with beliefs of my own. So please dont start a religion war with me.
Okay so picture our entire life, The people you know, everything you see and experience from the time you are born until the time you die, as one big picture frame. Now, picture a human transport belt (those things you walk on at airports and such). Picture rows and rows of frames on the belt. These many frames all represent different dimensions. they all travel at the same speed. But we cant jump back and forth between them... at least yet... Now suppose that the frame in front of yours is one second ahead in time. and the one behind yours is one second behind. And as the frames all move down the line, they all become more advanced and civilized.
Now, in my eyes, nothing in the world is perfect. so imagine that somewhere these frames cross lines with each other.. this would explain paranormal activity. Also, is it possible that some advanced dimension down the line figured out how to jump dimensions? that would explain the extra terrestrial. Of course eventually, we all die. This is where you would fill in the blank based on what you believe. If you are christian, you may believe that your frame falls off the end and you go on to face judgment day.
If you believe in reincarnation you may chose to believe that you start back on another frame all together.
Keep in mind this is all a big metaphor. Obviously life isnt a picture frame
Please dont bash me, Its merely just an idea!