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$\begingroup$This is far too broad a question to be answered here. There are numerous books and blog posts on the subject. You need to go off and do some reading around the area and come back to us if there are any specific technical issues you need clarifying.$\endgroup$
$\begingroup$@New_new_newbie : Feel I now need to promote String Theory in face of Smolin! So 'at' user24176 try reading The Fabric of The Cosmos by Brian Grene. I read it as a first year undergrad and really loved it. I hear there is also a movie now, but I cannot comment on it. Moreover, I believe that one can watch it online, but I'm unsure where.$\endgroup$
The Trouble With Physics', or
Three roads to quantum gravity' by the same author. $\endgroup$