“Time passes”, “Time waits for no one”, “As time passes”: When we talk about time, we tend to strongly imply that the passage of time is some kind of real process happening in the world. We live in the present moment, moving through time as events come and go, fading into the past.
However, try to actually verbalize what the flow and passage of time means. What flow? Rivers flow because water is moving. What does it mean to say that time passes?
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Humans have been thinking about time for as long as there are records of humans thinking about anything. The concept of time necessarily pervades every idea about yourself and the world around you. That is why, as a philosopher, I have always considered philosophical and scientific developments in our understanding of time to be particularly important.
ancient philosopher who keeps time
Ancient philosophers were very skeptical about the whole concept of time and change. Parmenides of Elea was a Greek philosopher from the 6th to 5th centuries BC. Parmenides wondered how events could pass from the future to the present to the past if there was no future yet and no past anymore.
He reasoned that if the future is real, it is also real now. And if all that is real now is what is now, then the future is not real. Therefore, if the future is not real, then the occurrence of present events is a case of something mysteriously arising out of nothing.
Parmenides was not alone in his skepticism about time. Similar reasoning about the contradictions inherent in the way we talk about time appears in the writings of Aristotle, the ancient Hindu school of thought known as Advaita Vedanta, and Augustine of Hippo, also known as St. Augustine, to name just a few.
Einstein and the theory of relativity
Early modern physicist Isaac Newton assumed an unrecognized but real flow of time. For Newton, time is a dynamic physical phenomenon that exists in the background, a regularly ticking cosmic clock that can objectively describe all motion and acceleration.
Then along came Albert Einstein.
In 1905 and 1915, Einstein proposed the special theory of relativity and the general theory of relativity, respectively. These theories verified all long-standing doubts about the very concepts of time and change.
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The theory of relativity rejects Newton’s concept of time as a universal physical phenomenon.
By Einstein’s time, researchers had shown that the speed of light is constant, regardless of the speed of the light source. To take this fact seriously, he argued, was to regard the speeds of all objects as relative.
Nothing is ever really still or really moving. It all depends on your “frame of reference”. A frame of reference determines the spatial and temporal coordinates that a particular observer assigns to an object or event based on the assumption that it is stationary relative to everything else.
Someone drifting through space sees a spaceship passing by on their right. But the universe itself is completely neutral as to whether the observer is stationary and the ship is moving to the right, or the ship is stationary and the observer is moving to the left.
This concept affects our understanding of what watches actually do. Because the speed of light is constant, two observers moving relative to each other will assign different times to different events.
In a famous example, two equidistant lightning strikes occur at the same time, and an observer at a train station can see both at the same time. An observer on the train assigns different times to the lightning strikes, moving toward one lightning strike and away from the other. This is because one of the observers is moving away from the light coming from one blow and towards the light coming from the other blow. The other observer is stationary relative to the lightning strike, so the light from each observer reaches him at the same time. There is no right or wrong.
The amount of time that passes between events, and the time at which something happens, depends on the observer’s frame of reference. Observers moving relative to each other will disagree about what events are currently occurring at any given moment. An event that is happening now, according to one observer’s calculations, will happen in the future to another observer at any given time, and so on.
Under the theory of relativity, all times are equally real. Everything that has ever happened or will happen is happening now to the virtual observer. There are no events that are merely potential events or mere memories. There is no single, absolute, universal present, and therefore there is no flow of time in which events seem to “become” in the present.
Change means that the situation is different from time to time. I always remember one thing. In later moments I remember even more. That’s how time passes. This doctrine is widely accepted today among both physicists and philosophers and is known as “eternalism.”
This brings us to a very important question. If the passage of time doesn’t exist, why does anyone think it does?
Time as a psychological projection
One common option is to suggest that the passage of time is an “illusion.” Exactly as Einstein famously explained at one point.
Calling the passage of time an “illusion” suggests that our belief in the passage of time is misleadingly the result of a false perception, as if it were some kind of optical illusion. However, I think it is more accurate to think that this belief stems from a misunderstanding.
As I suggest in my book A Brief History of the Philosophy of Time, our sense of the passage of time is an example of psychological projection, a type of cognitive error that involves misunderstanding the nature of our own experience.
A classic example is color. A red rose is not actually red per se. Rather, roses reflect certain wavelengths of light, and the visual experience of this wavelength can cause a sensation of redness. What I’m trying to say is that roses aren’t actually red, nor are they conveying the illusion of redness.
The visual experience of red is simply a matter of how we process objectively true facts about roses. It is not wrong to distinguish roses by their redness. Rose lovers do not make deep claims about the nature of color itself.
Similarly, my research suggests that the passage of time is neither real nor an illusion, but a projection based on how people understand the world. Just as we cannot explain our visual experience of the world without reference to the colors of objects, we cannot explain the world without reference to the passage of time.
I can say that my GPS “thinks” that I have gone in the wrong direction without seriously committing to me being a conscious, thinking being. My GPS is unconscious. So while we don’t have a mental map of the world, it’s safe to assume that the GPS output is a valid representation of our location and destination.
Similarly, although physics has no room for a dynamic passage of time, time is effectively dynamic for me as far as my experience of the world is concerned.
The passage of time is closely tied to how humans express their experiences. Our images of the world are inseparable from the conditions under which we, as perceivers and thinkers, experience and understand the world. The depictions of reality that we come up with are necessarily infused with our perspective. The error lies in confusing our view of reality with reality itself.
This edited article is republished from The Conversation under a Creative Commons license. Read the original article.
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