The holy grail for 21st century physics is to produce a unified theory of everything that can describe the world at every level, from the tiniest particles to the largest galaxies. Currently the strongest contender for such a theory is something called M-theory. In this video Costis Papageorgakis from Queen Mary, University of London tells us more about this "mother theory".

You can also find out more about M-theory in this article.

This interview is part of our Researching the unknown series featuring physicists from Queen Mary, University of London.