Here we have a recent talk from Caltech, which is dedicated to the 50 years anniversary of the discovery of quasars. After 50 years the research of quasars is still alive and kicking in astronomy, astrophysics and cosmology. Professor Rees gives a great overview of the progress in astrophysics, cosmology and space science since the discovery of quasars. This is discussed in a wider context by presenting how important discoveries in astrophysics are made and what they mean to science. As always, for more videos visit our video section and the Caltech channel.