Our concept of time was drastically altered by Einstein’s realization of relativity. He realized that the speed of light is the same, no matter what individual measures it and no matter that individual’s relative speed. This means that time passes by at different speeds depending on which individual’s perspective we are talking about. Before Einstein, we had a clear and logical sense that time ticks at the same speed everywhere in the universe, that an hour spent sitting on a couch (0 mph) was equivalent to an hour spent speeding down a highway at 70 mph. We now know that is not true. Despite the fact that our experiences in every day life lead us to believe that time ticks by at the same rate everywhere, it is simply not true.
What I am trying to wrap my head around is an idea similar to the question: does a tree in a deserted the forest make a sound, since no one is there to hear it?
I have always had an assumption, due to my mundane experiences, that when something is happening in one place at a particular time, at that exact moment everyone else is experiencing that exact moment (no matter what they’re doing) at the very same time. However, if time flows at different rates, what is this exact moment to me, when compared to everyone else? Compared to myself, is there a moment occurring at the same time at the other end of the room, the world, or the galaxy? This enters into the realm of questioning the existence of things outside my awareness, which I do not want to do. But, if everything is literally on a different time schedule because of relative motion, how can there be a NOW that every individual thing in the universe can agree upon? I like to believe that there is such an objective clock ticking away the TRUE time, whatever that may be, but this could be simply wrong, as we were back before Einstein.
Physically speaking, I wonder whether this cosmic clock has any truth to it because it all depends on observations. If I were traveling at half the speed of light towards the sun, and wanted to know what time it was back on earth, the information (assuming it traveled at the speed of light to reach me) would take time to reach me. Or if I were to turn around and head back, it would take time to get back to earth before I knew the time on earth. Since instantaneous transmittance of information is impossible, how then could I know if there truly was a single NOW throughout the universe?
Even events cannot transmit their implications instantaneously - if the sun were to vanish, it would take about 8 minutes for the earth to quit its orbit and sail into outer space, because even gravity is bound by this universal law of relativity.
My questions to you:
Is there some cosmic clock ticking the exact time EVERYWHERE in the universe, or does the fact that there is no NOW for everything mean that every individual is experiencing a different NOW?
If an event occurs NOW, at the other end of the galaxy, does it really happen NOW, if no one is there to observe it and the information physically cannot be known until light years later?
The thought and implications perplex me.