Positive Feedback
1

        Wrong, you thought we were going to start right in on those pesky terms and concepts I listed in the title. Actually, we are first going to discuss a concept that is nearly universally ignored in school and in science, positive feedback. Why is it ignored? Quite frankly, it's not nice.
        Positive feedback messes up theories. It gives problems so many variables that we used to ignore it to avoid the hassles.
        Let's start with one of the all time biggest negative feedback theories and see what happens when positive feedback is added to the mix. Darwin's original 'Theory of Evolution' has been summarized as 'Survival of the Fittest'. The negative feedback, death, operates on a species to improve its survival in nature. Is this a valid summary?
        Consider an over simplified example: Biologists agree that many of the most efficient plants are flowering. Flowering plants have a flexible means of reproduction and an efficient growth cycle. We have a hill covered with a comparatively inefficient plant, a non-flowering tree. Why don't the flowering plants dominate the hill?
        Let us go back in time to the hillside years ago. A large-scale natural event occurred eliminating the organic growth on the hill. It could have been a fire or a farmer plowing it up. One of the first plants back on the hill happened to be a tree. Because it was first, it dominated the growth around it. The tree's branches shaded the ground. Its roots sucked up nutrients, water, and took up space. This domination prevented other plants from successfully competing with it. (This first come first served idea is how we describe positive feedback in many everyday conversations.) The result of this positive feedback is a hill covered with a less efficient plant.
        Another concept of Darwinian Evolution is that a genetic mutation that produces an improvement for a species will, over time, become a characteristic of the species. All of us who had high school biology may remember that a recessive gene only has a one in four chance of being passed on to offspring. If you study the genetic dynamics of a large population, you will discover that a recessive mutated gene will be absorbed by the population and lost in a few generations. Every generation has a three times greater chance of eliminating the gene from it's offspring, than continuing carrying the mutation. Therefore, it is required that the only successful way for most genes to become a major characteristic of a species is if you limit the population that is breeding and put it under stress. This is what man does artificially when we breed different kinds of wheat, corn, dogs, cats, etc. We find a characteristic we like and carefully breed for that factor until we get a population of corn that is sweeter or a breed of dog with shorter hair.
        A newer evolutionary theory has been designed to take into account positive feedback. This newer theory does handle many of the problems not addressed by older versions, but not all. Species will exist for millions of years with little or no change, because of positive feedback. A change in species characteristics will only occur in a population that is both under a stress and isolation. A squirrel will not develop into a new species of squirrel unless you have only a few animals isolated on an island or mountaintop with environmental strain forcing the selection of new characteristics. This is seen over and over again in places like the Galapagos Islands, Hawaiian Islands, Antarctic, or even a mountaintop in the desert SouthWest.

2

        Let's look at something you can get your hands on, the QWERTY keyboard. QWERTY comes from the first row of letters on the standard typewriter style keyboard. No one knows for sure why the typewriter keyboard is laid out the way it is. The explanation that is most widely accepted is that the first typewriters would jam if the keys were pressed too quickly. Someone decided to scramble the keys to make it harder to type at high speed and QWERTY was born.
        For over half a century there have been keyboard designs based on how frequently a key is pressed. People trained on these new designs learn faster and type faster. Even people who learned to type on a QWERTY can in days improve their speed.
        Why don't we just change to a new keyboard design? Positive feedback. People who learned on the QWERTY are the ones who buy the most new machines. They remember the time and trouble they had learning the old keyboard and refuse to ignore that investment. Outside factors or a huge improvement in speed are the only things that can overcome the force of positive feedback.

3

        Anyone who has studied the automotive industry and physics can tell you that there are better engines, drivetrains, and fuels then those used today. I could talk about any of these examples, but let's just look at one, gasoline, to start with. We all know that eventually we will have to use a cleaner fuel that is either more abundant or renewable. Why don't we change now? Industry will give all sorts of excuses, but the real reason is positive feedback.
        Because gasoline was the most dominant of the first automotive fuels, everything involved with the car becomes dependent on it. To change the fuel you need to change not just the engine, but the gas station, refineries, pipe lines, fuel trucks, and repair shops. Finally this change has to be done at close to the same time. This means that once a positive feedback system forms, there has to be drastic outside forces to change it. In the case of gasoline this could be an environmental catastrophe, a massive fuel shortage, or a forced governmental regulatory change. Surprisingly the least harmful outside force is also the least likely to occur, governmental regulation.
        For a new fuel to come into use without outside forces it would have to be many, many times superior to gasoline. When an industry or government spokesman refers to the idea that 'natural' market forces will cause an orderly change to a more efficient fuel without major problems, you now know it will never happen. This is just one of the popular ideas spoken by people as 'common sense' that fails to stand up to reason when viewed using concepts required to understand non-linear systems.

4

        An interesting historical note can show how sensitive a system with positive feedback can be at the beginning, of its formation, to starting factors.
        At the beginning of the automotive age there were a few different engine designs. Possibly the best was the steam car. Railroads with steam engines had been around for years. The fuel for a steam car was much safer and easier to use and obtain. Why no steam cars today? Hoof and mouth disease. There was an outbreak of hoof and mouth disease in this country at the turn of the century. To try to control it public horse toughs were closed and water for steam cars became hard to find. (A water recycler for steam engines was developed a few years too late.)
        One last event sealed the fate of the steam car, a car race that all of the national newspapers covered. This race was one of the first national races ever held. Cars were new and parts were untested. Tires would last only a few miles. Bolts that worked well with carriages broke within hours on cars. By chance the car to survive long enough to win this 'national' race happened to have a gasoline engine. Therefore, all the national press reported that the best car was gasoline. No one wanted to invest or buy a second best car so at a critical time funding went to the development of the gasoline car.

5

A successful positive feedback system does self-destruct. Most of the changes in systems that occur happen in cataclysmic events. We fail to recognize a war or a failure of an economy as the natural action of positive feedback. Let's look at a small event that most people are familiar with. This should help make the actions involved easier to understand.
        The old LP records or even the eight-track tapes were very successful products. Neither fulfilled their full potential. Many do not know that there was a great deal more that could have been done with both technologies. Longer playing times and better quality sound reproduction had been under development for years at the time of their demise.
        What happened? They both suffered from their own success. They had developed into standard play times and quality. Anything different had trouble competing with these standards. The status quo kept the basic designs in the market without the gradual improvements possible in the technologies. Eventually new products were sold that had the improvements that were gradually being desired by those who used the older technologies and that the market wouldn't let develop. They were replaced by the CD and cassette.

Summary

        Positive feedback causes a stable system to form. The system is probably not the most efficient one, but it is an adequate one. The stable system will eventually build up external and internal forces, just because of its success. The forces, over time, will either force a cataclysmic modification in the system or its destruction and replacement by a new one.
        Positive feedback is one of the main factors in creating a non-linear system. Positive feedback is the force in nature that produces most of the non-linear characteristics we recognize, such as sensitivity to starting conditions and multiple stable answers to the same question. Therefore, any method that is used to solve non-linear systems has to take into account positive feedback. Because small differences at the beginning can cause greatly different final results, methods of increasing the amount of starting data or simplifying the data have to be used. Hint: unique ways of doing both are coming up.

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