Some of us are wondering: how is the universe we live in, how long has it existed and above all how long will it last? Many, on the other hand, prefer not to think about it so much, the answer does not exist and in any case it does not interest us, what surrounds us seems to have always existed and it is not worth asking these questions. However, man has always asked himself these questions since ancient times and many philosophers have filled pages and pages with hypotheses on the possible end of the world. Today we have been able to understand how the universe has evolved up to our days, but the very first moments of its existence remain obscure and above all what could have been before its birth, if there was a before. It is not yet known how the universe could evolve in the future, how it could end and what could exist after its end. In this paper the author tries to give some possible answers and, in order to be able to easily delve into the complex laws that govern the genesis and evolution of the cosmos, at the beginning of this text the theory of relativity is briefly illustrated, that of quanta and the most recent string and loop gravity theories.