| Abstract Note | Why do most ‘elementary particles’ which form the constituents of all matter have a non-zero mass? Strange question, apparently in contradiction with our physical intuition. In this little book we attempt to explain that the question is far from being trivial and that the answer can be found in the recent discovery of a new particle in the Large Hadron Collider (LHC) at CERN near Geneva. We offer the reader a guided tour, starting from the tiny fractions of a second after the Big Bang, when all particles have been created, to the present experiments we perform in our laboratories. We show that the Universe follows a profound symmetry principle which seems to determine the structure of the world. |