Now, let's tackle the key ideas of special relativity:
Einstein explored the consequences of the absoluteness of light speed and motion at relativistic speeds (relativistic means near the speed of light) using “thought experiments.” In the following pages, we will explore the postulates of special relativity and explain them through thought experiments.
The consequences of special relativity will be easiest for us to visualize with thought experiments involving spaceships in freely floating reference frames (inertial reference frames). This means that the spaceships are not influenced by gravity – assume there are no massive objects nearby, and are moving at constant velocities – no acceleration.