Einstein's Theory of Special Relativity

 Norton describes what Einstein’s theory of special relativity is and what it is not. What Einstein's theory of special relativity is the idea that two events occurring at the same time are not universally occurring at the same time as it depends on the viewpoint of the observer. What it is not is what Norton defines as what we call, “appearance simultaneity,” and this means that the theory does not include the senses of an event. 

The theory of special relativity is illustrated by Norton. An observer stands in the middle of a long platform that has endpoints labeled A and B where two momentary flashes of light occur at each. The lights arrive to the observer at the same moment and come from equal distances away. Due to the observer's frame of reference, these events are  simultaneously occurring. Now if the platform were to be rapidly moving in the direction of A towards B, the observer will have a different observation of this event due to them also, being at the midpoint, moving relative to the platform. The same flashes will occur from both sides, but to the new observer the flash from A happens earlier than the flash from being because the observer is moving away from A and towards B.

On the other hand, appearance simultaneity gives the observer the sensation that two  events happen at the same time when it is reality they may not have. What happens in this scenario is that the observer’s sensations lead them to believe that two events are simultaneously occurring. Norton illustrates this through  the example of you being under a tree and hearing thunder and seeing lightning. For you the two events of thunder and lightning are simultaneous, but for someone standing on a hilltop in the distance, there is a flash of lightning and seconds later the boom of thunder. For the  observer, the events are not simultaneous. Another example he provides is that of us looking at a galaxy 10 light years away from us; we are viewing this galaxy in our present day now when in reality the galaxy we are seeing is that galaxy 10 million years ago. 

Under this theory, I see time as an illusion; the time is defined by the viewpoint of the observer. Depending on where the observer is, the time will either be faster or slower.