I should elaborate on ActorSelection: while this is how you look up an actor reference, it's not inherently a 1-1 lookup to a single actor.
Technically, ActorSelection does not point to a specific ActorRef, it points to every ActorRef that matches the expression given. Wildcards are supported in this expression. So it's an expression that selects 0+ actors
ActorSelection will also match two different ActorRefs with the same name if the first one dies and is replaced by another (not restarted, in which case it would be the same ActorRef).
Technically, ActorSelection does not point to a specific ActorRef, it points to every ActorRef that matches the expression given. Wildcards are supported in this expression. So it's an expression that selects 0+ actors
ActorSelection will also match two different ActorRefs with the same name if the first one dies and is replaced by another (not restarted, in which case it would be the same ActorRef).