I Am a Strange Loop - Douglas R. Hofstadter [46]
Enigmatic, Emergent Reverberation
At some point during the session, I accidentally stuck my hand momentarily in front of the camera’s lens. Of course the screen went all dark, but when I removed my hand, the previous pattern did not just pop right back onto the screen, as I expected. Instead, I saw a different pattern on the screen, but this pattern, unlike anything I’d seen before, was not stationary. Instead, it was throbbing, like a heart! Its “pulse rate” was about one cycle per second, and over the course of each short “heartbeat”, the shapes before my eyes metamorphosed greatly. Where, then, had this mysterious periodic pulsation come from, given that there was nothing in the room that was moving?
Whoops — I’m sorry! What I just wrote is a patent falsity — there was something in the room that was moving. Do you know what it was, dear reader? Well, the image itself was moving. Now that may strike you as a fatuous, trivial, or smart-alecky answer, but since the image was of itself (albeit at a slight delay), it is in fact quite to the point. A faithful image of something changing will itself necessarily keep changing! In this case, motion begat motion endlessly because I was dealing with a cyclic setup — a loop. And the original motion that had set things going — the prime mover — had been my hand’s motion, of which this video reverberation now constituted a stable, self-sustaining visible memory trace!
This situation reminds me of another loopy phenomenon that I call “reverberant barking”, which one sometimes can hear in a neighborhood where many dogs live. If a jogger passes one house and triggers one dog’s bark, then neighbor dogs may pick up the barking and a chain reaction involving a dozen dogs may ensue. Soon the barking party has taken on a life of its own, and in the meantime its unwitting instigator has long since exited the neighborhood. If dogs were a bit more like robots and didn’t eventually grow tired of doing the same thing over and over again, their reverberant barking could become a stable, self-sustaining audible memory trace of the jogger’s fleeting passage through their street.
The dynamically pulsating patterns that I encountered in my video voyage were completely unlike the unwavering “steady-state universes” that I had observed up till then. Stable, periodic video reverberation was a strange and unanticipated phenomenon that I’d bumped into by accident while exploring the possibilities lurking in video feedback.
Even today, all these years later, the origins of such pulsation remain quite unclear, even mysterious, to me; for that reason, it is an emergent phenomenon, otherwise known as an epiphenomenon, as discussed in Chapter 3. In general, an emergent phenomenon somehow emerges quite naturally and automatically from rigid rules operating at a lower, more basic level, but exactly how that emergence happens is not at all clear to the observer.
I admit to feeling a little dense for not having fully fathomed what lies behind video reverberation, but at this point I am so accustomed to it that it “makes sense” to me. That is, I have a clear intuition for how to induce it on the screen, and I know that once it starts, it is a robust phenomenon that will continue unabated probably for hours, perhaps even forever, if I don’t interfere with it. Rather than trying to figure out how to account precisely for video reverberation in terms of phenomena at lower levels, I have come to just accept it as a fact, and I deal with it at as a phenomenon that exists at its own level. This should sound familiar to you, since it’s how we deal with almost everything in our physical and biological world.
Feeding “Content” to the Loop
As I mentioned at the outset, one lucky thing about the Stanford setup was the seemingly random metallic strip on one side of the television set