As it returns to the stage this month, Digital Spy spoke to the stars of the two-hander - Rafe Spall and Sally Hawkins - and here's what they had to say.
"At it's core it's a romantic comedy - it's about a boy and a girl who get together," Spall said.
"The boy is a beekeeper and the girl is a quantum physicist... who works in the field of multiverse.
"The idea that every decision that you ever make, there's another you in another universe - a parallel universe - making a different decision an infinite number of times. The structure of the play reflects multiverse.
"You'll play a scene, then you'll change universes and play the scene in a different way, if the character had made a different choice. It's about consequence and the choices you make."
Hawkins said: "The rewind of it is quite thrilling to play - it's quite fun to do that."
Constellations runs Monday to Saturday at 7.30pm until Saturday, January 5, 2013 at London's Duke of York's Theatre, with Wednesday and Saturday matinees at 2.30pm.
Tickets are priced at £10, £25 and £37.50, and concessions and group discounts apply.