Teddy told me that in Greek, nostalgia literally means 'the pain from an old wound'. It's a twinge in your heart, far more powerful than memory alone. This device isn't a spaceship, it's a time machine. It goes backwards and forwards and takes us to a place where we ache to go again. It's not called the wheel, it's called The Carousel. It lets us travel like a child travels; round and round and back again, to a place where we know we are loved.
Nostalgia doesn't mean "pain from an old wound". Νόστος = the return to your homeland. + άλγος = pain. So it literally means pain from the longing to return home, and metaphorically it means longing to return to a psychologically-fulfilling past condition/situation/state.