Here are my less-than-scientific theories about this terribly puzzling and highly trivial matter, culminated from my own thoughts and a number of conversations with friends.
Splicing theory
Memory loss leaves holes. However, remaining memories do not play back like a tape on which areas have been erased, and on which the “empty” spots or silent areas still take up time when played back. Rather, the remaining memories are “spliced” together, leaving no time gaps. This results in a “condensed” memory continuum. Because the frequency of memory loss increases each year, leaving fewer “fragments” from which to construct the memorized year just past, each year that passes seems shorter (in memory) than the one that preceded it. (Or at least it would seem shorter if you could still remember the one that preceded it.)
Absorption vs. Deflection theory
As children, we pay close attention to everything happening around us, and we absorb sensory input like sponges. As we age and begin to take a lot of familiar sensory input for granted, we start to “deflect” or “discard” large portions of our daily experiences. This is a different take on the splicing theory above, in which involuntary memory loss is the culprit. The deflection theory contends that at least some of the memory loss is a result of our consciously or deliberately discarding portions of our sensory input. To use a computer analogy, we choose not to write/save some of our experiences to “disk.”
Constant-forever theory
If “forever” is defined as the period of time from the beginning of your personal memory (conception, birth, infancy, or whatever) to the current time (or “now”), this theory contends that the perceived length of forever is constant, so that as each year passes, the beginning of memory (or the beginning of personal time) never seems to be any farther in the past. In other words, as a child, possibly even from within the womb, the beginning of personal time seems just as far in the past as when you are old. Whether you are two years old or ninety-nine years old, the length of your life just seems like “forever.”
In youth, a year still seems very long (and slow) because it takes up a very large and significant percentage of the constant-length reverse-looking “forever.” (I believe this perception of years advancing slowly contributes to the common — and incorrect — belief among youth that they have all the time in the world to plan for career, retirement, etc.)
As you age, each year that passes takes up a smaller percentage of the constant-length “forever continuum,” and is therefore perceived (in memory) as taking up a shorter period of time. This often results in ever-increasing amazement regarding the speed with which years seem to pass in later life. Of course, increased awareness of — and concern about — one’s own mortality can also contribute to a desire for the years to “slow down again.”
Final Word
I’m sure the right people could easily discount, disprove, or ridicule all of these theories, but who cares? It’s fun to think about things like this, isn’t it?
