The Dispossessed by Ursula K. Le Guin

'There was a wall. It did not look important - even a child could climb it. But the idea was real. Like all walls it was ambiguous, two-faced. What was inside it and what was outside it depended upon which side of it you were on...'
 
Shevek is brilliant scientist who is attempting to find a new theory of time - but there are those who are jealous of his work, and will do anything to block him.

So he leaves his homeland, hoping to find a place of more liberty and tolerance. Initially feted, Shevek soon finds himself being used as a pawn in a deadly political game.