public static void checkCollision(ActorSet actors, int start, int stride){
        // TODO it would be nice use a single list for all our threads
        List<Actor> actorsList = actors.getCopyList();
        // Check our guy we stride to against all the others
        for(int i = start; i < actorsList.size(); i += stride){
            Actor a = actorsList.get(i);
            // Don't collide with actors we added this frame to prevent or minimize runaway collision
            if(a.getAge() == 0)
                continue;
            for(int j = i + 1; j < actorsList.size(); ++j){
                Actor b = actorsList.get(j);
                if(b.getAge() == 0)
                    continue;

                if(a.isColliding(b)){
                    a.handleCollision(b);
                    b.handleCollision(a);
                }
            }
        }
    }