Is Time Travel Possible ?

Time travel has been the main topic of science fiction and has fascinated human minds ever since H G Wells' 'Time Machine'. But i think actually it is not possible because of the revolution of the theory of relativity. It is known that space and time are intertwined. Any body that has mass causes the space-time around it to curve so that it accommodates that body with mass. You can only move forward in time, although you can move forward and back in any of the three spatial directions.