Space

"Space is big. Really big. You just won't believe how vastly hugely mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space."
— Douglas Adams

Most significantly for magic users, there are no connections to the Aether in space. That means that magic doesn't work in space, unless you take mana batteries with you.