We all heard it many times, [the theory of Time](http://everythingforever.com/einstein.htm) suggest it is parallel rather than being linear. This leaves the door opened for alternate realities and well, immortality.

However, even after reading tones of lines and watching tones of documentaries, I still cannot understand how it makes sense while everybody in the scientific community seems to accept a theory they yet cannot prove.

I don't understand how the past, present and the future can exist at the same time. I cannot warp my head around the idea that our younger and grown selves are somehow "living" at the same time creating different versions of ourselves in an infinite loop that is... 

How can the 5 year old me still be out there while the 28 year old me is here? That means the 56 year old me is already out there?

Does it mean that our lives are already predefined? I have so many questions but I will end it here in order to stay relevant to the topic.