A Fly Fisher's String Theory

This article was originally titled "String Theory" in the Seasonable Angler column of the Feb-March 2015 issue of Fly Fisherman magazine.

The month before graduation was reserved for modern physics. That term always made me smile because some of those topics were over one hundred years old.

Only the final topic of string theory was younger than my teenage students. When those high school seniors came to my introductory physics class in August, they were two-dimensional thinkers. Their algebra skills allowed them to solve problems only in the horizontal or the vertical plane. Trigonometry could drag them grudgingly into three dimensions, but that was a huge intellectual leap for most of them.

To reach the fourth dimension we factored in time, allowing us to calculate a particle’s velocity. That was about all their teenage brains could handle, and fortunately that was about all they needed to get by and move on to college. In Isaac Newton’s world, all you needed was the position of an object and its velocity. From those four dimensions you could predict where that object would go in the future, and where it had come from in the past. For most of the history of physics that was sufficient. In the last one hundred years however, the need for more dimensions arose.

Newton reasoned that all objects from apples to planets could be treated mathematically as particles. Although he figured out how the force of gravity worked, he never figured out what gravity was. He might have been pleased to learn we now believe all the traditional particles of matter and all the fundamental forces consist of particles.

The string theory proposes that all these particles are actually vibrating strings. They are so tiny that it would take one hundred quintillion of them to stretch across the diameter of a single atom. These strings, and everything they make up, including humans and trout, exist in eleven dimensions where all but four dimensions are rolled up so tightly that we cannot perceive them. That theory works well to explain pretty much everything we observe. For that reason some folks also refer to it as the theory of everything.

The string theory that I have been working on since my retirement courses through a parallel universe. I have been developing a theory about how to consistently attach a string between my 5-weight rod and a trout.

It all began with my father. He loved to travel and often took us kids along. As a second thought the fishing rods might be included in the camping trailer. My father wasn’t much of an angler so neither was I. Eventually I evolved into a fly fisher, although my skills were based in two dimensions.

I tied flies using Jack Dennis’ Western Trout Fly Tying Manual and usually chose my nymphs at random.

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That was my fly-fishing version of the uncertainty principle. I’d then search for an area of the stream that appeared to be a few feet deep. I’d make an uneducated guess as to where to place the strike indicator and how much weight to use. These two parameters were rarely adjusted. Through these two-dimensional coordinates I drifted my fly and hoped for the best, which usually was the opposite of what I received.

Something was missing from my theory. In those years before DVDs and the Internet I was teaching myself the art of fly fishing through trial and error, relying mostly on error. For a few years my success rate was so low, and the demands of my profession so high, that I gave up fishing entirely.

Soon after retiring I decided it was high time to get more serious about fly fishing, so I hired a guide. As he looked over my shoulder he said “Toss the fly into that seam to the left of that granite boulder.” I felt the general direction he described couldn’t possibly hold fish, but to clarify I asked him, “What’s a seam?”

He patiently explained the concept to me and once I clearly understood where he wanted my fly, I did my best to put it there. To my amazement a brown trout rose out of nowhere and engulfed the offering.

As I took direction from the guide throughout the day, I realized there were fish in parts of the river that I used to walk right by. Later in the day we were standing midstream and the guide directed me to cast to the slow water along a bank. My straight-line cast brought instantaneous drag, so the guide suggested a reach cast. “What’s a reach cast?” I asked.

He looked surprised, tried to explain, and finally I handed my rod to him for a demonstration. A simple upstream reach resulted in a drag-free drift measured in feet rather than inches. By the end of the day I realized that whole new dimensions of this sport were unrolling before my eyes.

It was an epiphany. Thanks to this guide, this mentor, I finally had some clue of what the problems were and I had an inkling that there might be solutions. In retrospect I think some of my beginning students must have felt like I did. We were both getting our first glimpses into a whole new world through the eyes of another who had seen farther.

Over the next few weeks I watched DVDs and read books. I learned from Rick Hafele (Anatomy of a Trout Stream) that rivers have parts like riffles, pools, flats, and seams and that from all these you can take fish if you present the fly correctly. I had been looking for a single target, what Hafele might call a run, where in fact a river is a target-rich environment.

I learned from Doug Swisher (Selective Trout) that casting and mending techniques allow you to fish any water from any angle. I had been using a single cast, a single mend, and only a few angles. Now I had many lanes of approach. More dimensions of my string theory of fly fishing were unrolling.

As the summer progressed I practiced the new dimensions of my string theory. I felt like my former students solving new problems with freshly learned techniques. I learned to read the water better, and the number of fish I caught increased dramatically.

By fall I was filled with confidence as I approached a long riffle on the Colorado River. There was ice in the shallows and the water temperatures were in the upper 30s, but I was confident. To my shock the riffle seemed to hold nothing. I had lost the magic. The single fish I caught that day was taken from a deep run, just the kind of stretch that used to be my only target.

A speaker at our next Trout Unlimited chapter meeting gave me the answer to this turnabout. Trout do not spend all year in the riffles. As the water temperatures drop, the photosynthesis stops, the bug life hibernates, and the metabolism of a trout slows. The trout retreat to the deep runs to wait out the winter.

That riffle really was deserted and I was wasting my time there. I had unrolled another dimension for my string theory of fly fishing. This was a dimension of time, a seasonal migration. I altered my winter tactics and began dredging tiny midges through the depths of these holding lies. I started finding fish again in the dead of a Rocky Mountain winter.

As winter trudged on I was able to piece together parts of the puzzle I had read about but only now was beginning to internalize. Along with the seasonal migration of the fish there is a seasonal progression of the bugs. It makes more sense to try a Disco Midge in February than an RS2. Midges can carry out their life cycle in frigid water. The RS2 represents a Blue-winged Olive, and they aren’t on the move until March when the water warms a bit. Another dimension of time had unrolled.

Even though Mysis shrimp knock them dead on the Blue River in Silverthorne it makes no sense to try one on the South Platte—there aren’t any there. Different rivers have different bugs. Another dimension of space was unrolling. I no longer chose my flies with uncertainty. I now chose them with a purpose based on the river, the run, the time of year, the time of day, and the changing conditions I observed while in the moment.

Yet another club speaker described his theories of how the distance between the indicator and the split-shot controlled the nymph rig depth only when it was balanced with the correct amount of weight. The weight, he felt, was what determined the drift speed.

That made four new dimensions unrolling to control the movement of the fly. Three spatial planes resulting in an appropriate velocity for the fly that existed only in your mind’s eye seeing below what the indicator on the surface showed. In the same way that my students had progressed from two-

dimensional thinking to the string theory, my string theory of fly fishing had followed a similar path of increasing dimension, thanks to my many teachers.

No one can predict how far a path may take them as there are many dimensions yet unseen, but as Newton once said, “If I have seen further it is by standing on the shoulders of giants.”

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George Franklin is a retired physics teacher. He lives in Denver, Colorado.