In later episodes, where the Doctor travels into the future, the space-time vortex in the opening credits appears red instead of blue. Fans speculate that's because light emitted by an object ...

Vortex rings are pretty cool ... the pulses evolve toward stronger space-time nonseparability and closer proximity to the canonical Hellwarth–Nouchi toroidal pulses". The process, though ...

we see the TARDIS in flight from the outside as it travels through the space/time vortex. It’s not spinning on its axis yet though, which will become the standard in later years. After almost ...

A research team from Würzburg and Dresden has demonstrated the phenomenon predicted eight years ago. This could make data ...