The surprising answer is: nobody knows. Physicists, despite trying for almost a century to rule it out, have so far failed. The known laws of physics do not forbid time travel. In fact, they appear to make it easy - at least in principle.
Doctor Puppet is a series of stop motion animated shorts featuring characters and concepts from the sci-fi series ... "We are working on episode 6 and it will premiere at the end of August. We're actually doing something really different and exciting".
A lobster on a telephone, a clock that seems to have melted. These are some of the most famous images of the movement known as 'Surrealism', but what are they all about? Sex, mostly, explains the Dr Who actor and former art student, Peter Capaldi.