Special Relativity According to Einstein

Can two events occur at the same time? According to Einstein's special relativity, the answer is not a simple yes or no. Two events happening simultaneously may not be happening during the same time, since it is dependent on the viewpoint of the observer. In a definition, relativity of simultaneity states that "inertial observers in relative motion disagree on the timing of events at different places" (Norton). To help understand this relativity of simultaneity, let's assume that there is an observer at the midpoint of Point A and B. If two flashes of light are sent from these points at the same time, they will be simultaneous to the observer since he is at the midpoint. However, once this observer is moving relative along the length of the platform with the lights, this changes. If light is shot at the same time from Points A and B, one side will be received quicker than the other depending on which way the observer is moving (Norton). Or, if they are received simultaneously, then the one point waited to shoot its light. Therefore, the two events are not simultaneous according to the observer. So in conclusion, relativity of simultaneity is the idea that two events that happen at the same time is not absolute, but depends on the observer. 

Many times this relativity of simultaneity can be confused with appearance simultaneity. In this appearance simultaneity, events are "simultaneous if our sensations of them happen at the same time" (Norton). Likewise, they are not simultaneous in this sense if our sensations of them occur during different times. Additionally, during this we correct for differences in appearance simultaneously, meaning we justify it in our head. Norton illustrates this theory with an example of thunder and lightning. When we see lightning, we know is is followed by a loud boom of thunder. We correct this in our minds because we know that light travels faster than speed (Norton). So, even though the two events happen at different times, we believe it to be simultaneous because we know they come from the same thing. 

I believe that in Special Relativity, time is neither real nor unreal. In one sense time, timing lines up simultaneously with events. On the other hand, like when the observer is moving along the platform, time does not line up simultaneously with events. I think that time is a situational factor, and whether is is real or unreal depends on the situation. Time itself is simply an illusion and its reality is based off of the perception of the observer. 

Norton, John D. Special Relativity Basics, 2007, www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/Special_relativity_rel_sim/index.html.