MIT Philosopher Explains Why Time Doesn't Pass
When discussing the experience of time in layman's terms, people generally refer to the "passage of time," where the future does not exist yet and the present is an elusive "now" that soon becomes the past, which is lost to us forever. However, many physicists and philosophers alike believe that this is not the case, and that our experience of time "passing" or "moving forward" does not reflect the physical reality of time.
Dr. Brad Skow, an assistant professor who recently received tenure at MIT, explained that the concept of time is ultimately so complex, people tend to avoid directly talking about it. "When you ask people, 'Tell me about the passage of time,' they usually make a metaphor. They say time flows like a river, or we move through time like a ship sailing through the sea."
Physicists tend to conceive of a four-dimensional spacetime in which time is just another dimension, rather than a three-dimensional space that is modulated by time. In other words, time is a dimension that operates in the same way as height or width. As a result, different times are analogous to different locations; although we experience time as "moving forward," the theory of eternalism, or the "block universe" theory of time, states that the past, present, and future are all equally in existence, and our consciousness is present at a specific point in time. But just as places do not cease to exist when one leaves them, the past and future are not lost or imaginary simply because we are located in the present.
Some modify eternalism to create the "moving spotlight" theory of time, which is more compatible with our subjective experience. According to this theory, although the past and future "exist" just as much as the present, the current, ever-changing instant takes on the property of "absolute presence." Skow argues in a recent paper that this theory is not only needlessly metaphysical, but incompatible with special relativity. "I think that the moving spotlight is metaphysically extravagant," Skow explains. "It's got this extra mysterious thing - 'objective presentness' - that moves around. I wouldn't want to believe in that unless I saw good arguments for it... Contemporary physics doesn't need to use the objective passage of time to explain anything."
He succinctly elaborates his own "block universe" theory: "If you could look down on the universe, you would see things spread out in time as you would see the universe spread out in space. You could see that things are one way at earlier times and different at later times, but you wouldn't say the universe as a whole is changing."
Skow's teachings lie in the intersection between philosophy and science, and he stated that he has many physics students in his class. "They know a lot of quantum mechanics, [and they] tend to be very curious about questions they don't have time for" in their science classes.
Skow is of the opinion that not only is philosophy necessary for the comprehensive study of scientific concepts like time, but that science is integral to the study of philosophy. "I think it's as important for philosophers to know some physics as it is for them to know some [formal] logic," Skow said. "Maybe more important."