The Memory of a Memory

A year or so ago I came across my first-grade class photo online. The picture did not grab my attention merely because my six-year-old self was in it (that blond-haired tyke in the top row, second from the left). I was struck by the image of our teacher, Mrs. Stratton, whom I remembered as an old lady. There she was all right, but she was quite unmistakably a young woman. Yes, you can say that for a six-year-old, all grown-ups are old. But I had distinct memories of Mrs. Stratton being an old lady. How had I so badly misremembered her all these years?

The answer lies in the peculiar dynamics of memory. We tend of think of a memory as a snapshot of a past event filed away in a mental scrapbook somewhere. When it’s time to retrieve a memory, we open up the scrapbook, and there it is. The reality is something quite different. We aren’t looking at the snapshot of a past event, we are looking at a memory of a snapshot of a past event. The memory soon becomes the memory of memory, then the memory of a memory of a memory, and so on, ad infinitum. Just make a photocopy of a photocopy; do that a few times. The problem becomes clear. Our memories are inexorably degraded over time.

This is hardly news to most people, especially to those of us who were in first grade more than six decades ago. If we go thumbing through our scrapbook of memories, we discover that many of those old snapshots have faded with time, and some are now all but indecipherable. What remains are bits and pieces of sensory experience: a look, a smell, a snatch of song with the words garbled. Soon there is no way to reassemble the puzzle pieces into a coherent picture of the past.

We have this notion that the past is its own place that we could go back and visit some day. This, of course, is a standard trope of science fiction. Occasionally you will get legitimate scientists to speculate on how this might be theoretically possible. Albert Einstein’s good friend Kurt Gödel even did the math, based on the general theory of relativity, as a gift to the great man on his 70th birthday. But sooner or later you run into the grandfather paradox, which puts a bit of a damper on the whole enterprise. The grandfather paradox, in a nutshell, is this: what happens if your time machine lands on your grandfather in the past and kills him, thus eliminating your own future existence? You wouldn’t even be a memory and certainly in no position to venture back in time to accidentally erase yourself. Even if time travel is theoretically possible, no one has quite figured out how you can be in two places at once and yet nowhere at all.

Steven Spielberg explored the grandfather paradox in his 1985 film, Back to the Future. Michael J. Fox plays an American teenager who travels back in time in a souped-up DeLorean sports car and accidentally prevents his own future parents from meeting. Unless he can figure out a way to get them together, his own existence is imperiled. You might say he would be history, except his own history hasn’t started yet. A family snapshot he carries around in his wallet graphically illustrates his plight. As events conspire to keep his would-be parents apart, the images of his brother and sister start to fade, and he knows he will be next. (Spoiler alert: Mom and Dad do get together, and Michael J. Fox makes it back to future, which has undergone major changes due to his monkeying around with the past.)

As far as I am concerned, the only way to resolve the grandfather paradox – to say nothing of the second law of thermodynamics, which prevents time from moving backward – is to stop thinking of the past as a place. If it is not a separate place that has some sort of quasi-spatial dimension, then you can’t travel there and create temporal havoc. I am aware that Einstein’s teacher, Hermann Minkowski, theorized that past, present and future exist simultaneously in a four-dimensional space-time universe. However, these points in space-time are baked in and can’t be altered, so there is no real flow of time in any direction and no prospect that you would accidently run over your own grandpa in your souped-up DeLorean.

If there is no real flow of time, why do we think time passes? I would suggest it has everything to do with those memories of past events that we file away like snapshots in our mental scrapbook. Memory is what gives time traction; without it, there is no past event to mark duration. We know time comes to a standstill, because that it is experience of people who suffer from severe retrograde amnesia. Those mental snapshots of past events fade to nothing in a few seconds, and victims are condemned to live as if every moment were the only one.

What about those of us who can still remember the past? Is it really any different for us? Yes and no. Yes, we have memories to mark past events and to give us a sense of time passing. But we are wrong to think those memories are artifacts from another time. Each memory is called up fresh, often as a memory of a memory of an event that has long since disappeared. The past is only a thought, and once the thought fades, the past disappears along with it. In a sense, you can say an amnesiac sees the world more clearly than we do. They understand, as we do not, that right now is all there is.

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