This statement tugs at the strings of very theoretical physics theory.  To grasp what all is going on, a look at the Special Theory of Relativity   where t' is how fast time is moving, t is time, v is an objects velocity, and c is the speed of light is necessary.  This equation models how time acts  if the velocity of an object is less than or equal to the speed of light and says that the faster an object moves the slower time progresses for that object.

What the Special Theory of Relativity says in regards to this Norris claim is interesting.  If Chuck Norris could move at the speed of light then, theoretically, time would not be moving.  However, if he can travel faster than the speed of light, then the STR cant explain what is happening.  However if the trend of time slowing down is followed, then theoretically he could go back in time an unknown amount of time.  Upon doing so he could, indeed, punch himself in the back of the head.

Holy Chuck