Again, three observed dimensions of SPACETIME:
A traveler in a fast vessel takes off from Earth for the Centauri system and according to his onboard clock takes four years to arrival in the Centauri system four light years (Earth at 0-point time minus four years observed per the speed of light Centauri system to Earth) away. He had one massive continuous light show of a powering blast observed all the way to the Centauri system by all observers.
The Earth observer observes him to take eight years (time dilated), not four years, to arrival in the Centauri system, though the traveler would be observed to have only aged four years in those eight years of time.
The Centauri system observer observes him to come through a wormhole from Earth, instantaneously traveling from Earth to the Centauri system, though the difference on the traveler's clock would show four years of time passage.
At no time did the traveler exceed or even approach, must less reach, the speed of light, regardless of appearances. The traveler annihilated the barrier of "relativity" -- annihilating relativity -- to every external observer, the Centauri system NOT being minus four years to Earth but an unobserved and unobservable Schrodinger's cat-like box (t=0) REALTIME NOW to (t=0) REALTIME NOW which is minus four years (t=-1(history)), plus four years (t=+1 (history)). . . and/or counter-intuitively, plus four years (t=-1 (history)), minus four years (t=+1 (history)). The far Horizon always being (Planck equals t='1' ('Unity') and never anything but).