Albert Einstein the great scientist proved time relativity which we discussed in the previous topic which proves that as you travel faster time expands relatively to the observer from the Earth. This phenomenum had a very strange effect that length contracts in the frame of reference of that traveller. lets explain it in a simple way. Imagine that you are at Earth and you measured the length between two stars then the spaceship which holds the traveler starts its travel from one of these stars to the other with a very high velocity approaching that of light. Then the time you will observe is the relative time which is the expanded time. While the time in the spaceship is the time at the frame of reference of the event itself so its the time that the traveller feels which is not expanded. As the relative time at the frame of refernce of the spaceship did not expand but it did expand the traveller must feel that the length of the distance between the two stars has contracted so that the velocity stays constant for both frames.