It's been 100 years since Einstein broke the world of physics with his theory of general relativity. What better way to celebrate it than by having the Doctor himself explain it to us?
Of course, the caveat here is that anyone who's been binging Jessica Jones is going to have an a immediate visceral reaction to the sound of Tennant's voice.
Put those feelings aside! Remember the amazing science at work, and enjoy this adorable animation along with it.