Credit
-Lyrics from “Tonight, Tonight” by Smashing Pumpkins
But what exactly is time?
Philosophers have always attempted to understand and define the nature of time at least since Aristotle. After work done by Isaac Newton, many came to the conclusion that time is a concept with many aspects. That is to say, there are individual "times." This means to these philosophers, that to say an event happened at a certain time is to indicate that the event filled that part, or unit, of time.
Philosopher Gottfried Wilhelm Leibniz didn't agree with the Newtonian perspective. For Leibniz, there were events, which happen before, after, or simultaneously with each other. Time is basically the way we organize these relations in our minds. It is not consider an additional concept distinct from the things that stand in these relations.
Philosopher Immanuel Kant argued against Leibniz's claims. Kant maintained that time was neither something that exits in itself, nor an order of relations among things that exist in themselves. Kant claimed that time is merely a method in which our minds organize the experiences we have. For Kant, things that exist in themselves, outside of our minds and that are independent to us, are not in time.
Another philosophical investigation interest has been the way in which we experience time.
According to ordinary idiom, time flows. However, does it? Whenever you say, "Now is the present," no matter when you say it, you are saying something true. Furthermore, the present is basically when you are. Some philosophers believe this is because you and I are special: we simply live at the present. According to these philosophers, time does flow: First, some time is the past, then it is the present, and finally it is the future.
Other philosophers believe that now is just like here; here doesn't refer to a particular place, just the particular place you happen to be when you say it. These philosophers believe that you and I are not special. In other words, Time does not flow. It has many parts, just like space. We are living in one part of time, which to us is the present, just how like our physical location is our here.
Another philosophical perspective belief is that all the times (the past, present, and future) all exist simultaneously. According to this perspective, dinosaurs, caveman, and even dodo birds exist- just not where we exist.
Sources & Further Readings
Stanford University
University of Tennessee at Martin
Princeton University An Introduction of Space and Time by Bas C. van Fraassen
Wikipedia- Philosophy of Space and Time
Wikipedia- Eternalism (Philosophy of Time)