During the show in the finale of season 1, he breaks lightspeed and collides with a fast Particle that forms a singularity. In the show it has been mentioned many times that Barry is faster than light. read more
Now, to time travel he runs at a speed of more than mach 2 to go at such an immense speed that he breaks the time barrier and opens a worm hole through which he can travel to anywhere in time. read more