Marty! You’ve gotta come back with me!
…Back to the future.
‘Doc’ Emmett Brown: Back to the Future Part II
For as long as I can remember I have been curious about time. According to Einstein and others, it is another dimension like the three dimensions of length, width and height. I always found that confusing. I know that it time can be treated that way mathematically but time is clearly different from the other three dimensions (or more than three if we accept some theories about the universe). The nature of time falls into a branch of philosophy known as metaphysics which deals with questions regarding the fundamental nature of reality.
In the early 1900s there was a disagreement between Albert Einstein and Henri Bergson with a formal debate in April 1922. Bergson was a philosopher and mathematician who believed that Einstein’s ideas about space and time missed the point. The time in Einstein’s formulas was not the time that we know and understand. To Bergson, time is something that we know and experience because we live through it. When I first read about this debate in the book The Physicist and the Philosopher: Einstein, Bergson and the Debate That Changed Our Understanding of Time by Jimena Canales, I thought that Einstein was clearly right and Bergson was just guilty of ‘fuzzy thinking’. Of course Bergson is much smarter than I and it is a bit foolish to write him off so casually. The more that I have thought about this debate the more I have come around to Bergson’s point of view. No one that I know of has a truly definitive explanation of the true essence of time. It can be plugged into a lot of equations that deal with things like motion, but do these formulae really capture what it really is? I have a sense that both Bergson and Einstein were both correct in their own way but were not really talking about the same thing.
There are many ideas about the nature of time. There are the ‘a-theory’ and b-theory’ of J. M. E. McTaggart. The a-theory is that there is a distinct past, present and future. Events in the future come to be in the present and then exist in the past while in the b-theory there is nothing special about the present. In the b-theory what we call the present is only an artifact of consciousness with no special significance. We should not use the term ‘present’ but only speak of a specific time that we are experiencing. All events exist equally, regardless of whether they are before, at, or after, some specified time.
The b-theory is related to the idea of block time, or eternalism, where all of time exists forever similar to locations in space. One consequence of this might be that it is theoretically possible to ‘travel’ to some event that according to our perception is in the past or future.
The opposite of eternalism is presentism which holds that only the present exists. The past may or may not have existed, but it no longer does. An intermediate view is known as the growing block universe where the past exists but the future only exists as we ‘move’ into it. The totality of ‘time-space is therefore continually growing. This is sometimes known as ‘no-futurism’.
Another question is whether or not time has any existence separate from space and the objects within it. What if everything in the universe were to disappear. Would time still pass by withe no clocks or other objects/events to mark it? What does that even mean? What if everything in the universe was to stop moving and changing, including our thoughts and perceptions, every electron was frozen in place and then it all started up again with everything having the same position, momentum and velocity that it had when it stopped. Our minds would resume mid-thought. There would be nothing to mark that time had stopped. Could we say that some period of time had gone by? How could we determine how much time, either nanoseconds or millennia? How do we know that this has never happened or hasn’t happened repeatedly. Does the question have any meaning?
Next month I will talk about my ideas regarding the true nature of time.
Wayne
September 2025
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