Riding The Cycles
POSITIVE AND NEGATIVE FEEDBACK
Within a couple weeks, planet Earth will again reach a place in orbit that gives all of us twelve hours of daylight: No big deal for those who live near the equator, but for us in northern latitudes, the “vernal equinox” inaugurates six months of daylight domination. Go daylight! It ought to be declared a holiday for those plagued with Seasonal Affective Disorder! The creation is replete with cycles, or “periodicity.” Most obvious are the seasons, whose temperatures are driven by (though lagging slightly behind) the length and angle of daylight. This results from Earth’s yearly orbit and its rotational tilt as compared to the orbit. Daily cycles, or “circadian” rhythms are marked by Earth’s rotation as compared to the Sun. Another trigger in nature is the monthly cycle, marked out by the Moon’s orbit around Earth (and its associated gravitational influence).
Such astronomical cycles affect tides, temperature, light, growth, budding, flowering, blooming, mating, migration, prevailing winds, ocean currents, and on and on. More recently, scientists have learned that eleven-year sunspot cycles affect global temperatures, the auroras, and ozone concentrations. Interestingly, the week (our most familiar time-cycle) is not sourced in astronomy but in proclamation: “For in six days the LORD made the heavens and the earth, the sea, and all that is in them, and rested the seventh day. Therefore the LORD blessed the Sabbath day and hallowed it.” (Exodus 20:11).
In addition to time-stamped processes, a plethora of “biogeochemical” cycles persist. These involve changes within matter itself, such as the rock cycle, the nitrogen cycle, the carbon cycle, the water cycle, and so on. The book of Job acknowledges some of this, especially in 26:1-8, 36:26-29, and 37:11-12. I’ll just touch briefly on the nitrogen cycle: Nitrogen makes up 78% of our atmosphere, as the gas molecule N2. Plants need nitrogen not from the air, but from the soil, and neither as N2, but as nitrates (charged compounds of nitrogen and oxygen together). Nitrogen gas is “fixed” into nitrates in three separate ways: 1) by nitrogen-fixing bacteria in roots, soil, or water, 2) by decomposers producing ammonium ions from waste, those ions being converted by nitrite bacteria, and those ions being once more converted by nitrate bacteria, and 3) through direct fixation by lightning. Thus, nitrogen atoms can enter plants, and eventually animals and humans up the food chain. Meanwhile, N2 is returned to the atmosphere by the “denitrification” of leftover nitrates in the soil. Kudos to all the bacteria for their fine service to the environment!
Obviously, there is a remarkable functionality in all this. The working creation does a whole lot more recycling than we’ll ever do artificially. Yet I’m sure we also recognize the aesthetic value of these cycles—they exude variety and renewal. When winter comes, I’m usually quite ready for it. When a new day dawns, I possess a fresh outlook and energy lacking the evening prior. And there is a strategic benefit to such cycles as well, as illustrated by the “periodic principle in training.” I run, and coach track and field, and have learned to align with this principle. Think of it like pushing a child on a swing: A single push cannot achieve as easily the speed and height achieved by a series of smaller, well-timed efforts. Similarly, athletes repeat week-to-week, month-to-month, and season-to-season, to “push” a little more effort out of their training and performance each time around. In each cycle, the body recovers, resets to a new level, and accomplishes more with the next effort. A well-coached, disciplined athlete “peaks” at the right time of the season.
This application of periodicity is known as “positive feedback.” Imagine positive feedback as a growing spiral. I first encountered this term in studying electrical circuits, but have since found the concept in other scientific disciplines. As a life principle, positive feedback is powerful. This is what allows us to be faithful with little, and find ourselves increasingly entrusted with much. (Matthew 25:21) It allows our small obediences to foster habitual discipleship; opportunities arise anew, yet with familiarity from our past experiences. Positive feedback is a means by which God “makes all things new” (Revelations 21:5) as we mature in faith.
Yet positive feedback is not always so “positive” for us (in the other sense of the word). Things can spiral out of control. For example, if one believes the lie of inferior worth, that person may begin to make unhealthy choices. Such choices bring failings and damage, reinforcing the concept of insignificance, increasing the destructive behavior, and so on. And positive feedback can be just plain irritating, such as when a microphone “hears” a particular pitch in the loudspeakers, sends it back to the amplifier, to the loudspeakers, and so on until “waaaaAAAAAAHHHH!” Ouch.
Interestingly, today’s preoccupation with a perceived global warming threat is fueled by the belief that the “greenhouse effect,” a beneficial design in the earth’s atmosphere, is experiencing a positive feedback, or “runaway greenhouse effect.” Thankfully, God’s second post-Flood promise to Noah guaranteed that as long as we have Earth, we will enjoy normal cycles: “seedtime and harvest, cold and heat, winter and summer, and day and night…” (Genesis 8:22).
Enter negative feedback—another mechanism found in cycles. (“Negative” here does not mean “undesirable,” but simply “in the opposite direction”). Imagine negative feedback as a thermostat. Increased ocean temperatures, for example, result in greater evaporation, which produces greater water vapor for cloud-cover. This increases the amount of sunlight reflected back into space, reducing the amount of energy reaching the oceans. Negative feedback is illustrated practically in ec
onomics: As demand for a product or service increases, its price also increases, thereby reducing its attractiveness. If producers are on top of it, they increase supply, but this also decreases demand relative to that supply. Eventually, equilibrium is reached, and the cycle continues while negative feedbacks buffer any further changes.
A simple invention known as the “gyroscope” illustrates negative feedback. It is basically a spinning disk or ring mounted so as to be free to rotate in any direction. Through negative feedback, this device masterfully maintains orientation of the moving object (such as an airplane) in which it is placed. In small devices this can occur passively, such as when a force pushes the object one way, and the rotational inertia of the gyroscope resists changes in that direction (similar to how a spinning top stands itself back up when tapped). Yet when greater resistance is needed, electronic control can also be actively tied to the gyroscope, to apply increasing power to an engine, wing flap, or other control device.
Even in the earlier swing example, negative feedback is constantly at work making the experience fun: Decreased speed (kinetic energy) results naturally from the swing’s increased height (potential energy), and so the swing reaches a peak, and falls back as these two energy types are traded inversely once again. If it weren’t for energy loss due to friction, the cycle would continue indefinitely, even without the pushing.
I wrote about “dynamic equilibrium” in a previous essay. Such equilibriums result from negative feedback. So, while cycles abound in the creation, we might ask what we gain personally from considering this positive and negative feedback business. Perhaps we should look at some examples where both positive and negative feedback work in concert.
Our autonomic nervous systems control organs, muscles, and glands that we typically cannot (and usually wouldn’t want to) control consciously. Such controls include pupil size, salivation, heart rate, lung constriction, digestion, urine secretion, hormone levels, and blood sugar levels. So how does the autonomic system control these important, cyclical activities of life? Through both positive and negative feedback. The “parasympathetic” nervous system works in most cases positively (constricting pupils, stimulating salivation, contracting the bladder), and sometimes negatively (inhibiting heart rate, relaxing the rectum). Its counterpart is the “sympathetic” nervous system, which works in 
most cases negatively (dilating pupils, relaxing the bronchi, inhibiting digestion), and sometimes positively (secreting adrenaline, accelerating the heart). It’s a balancing act in which the positive without the negative, or vice versa, can be disastrous (and is fortunately rare), while the coordinated work of both is a thing of wonder (and splendidly normal).
In our walk of faith, what do we need: Restraint (like a thermostat) or provocation (like a spiral)? A hand over the mouth, or to shout through two? “Thou shalt nots”, or “Thou shalts”? I think both! What does God want to accomplish in us? And what does he want to undo? The gospel itself represents both feedback types: A person’s spiritual poverty may drive him or her to search instead for purpose and redemption. Poor results may motivate wise changes. Meanwhile, saved souls enthusiastically seek to win new ones. The church at large experiences both feedback types: Reacting to errors, extremes, or irrelevances of former traditions, we swing back the other way. A casual approach to the God of Love swings back-and-forth with reverence for the God of Righteousness. A pendulum falls to-and-fro between emphasizing man’s will and acknowledging God’s providence. Over the ages, the church has sought to find the relevant place for its time, and the Spirit has kept the center. Yet within all this constraint we enjoy the positive feedback of fellowship, and we “stir up love and good works” in each other (Hebrews 10:24). Massive growth in the early church was driven by the positive feedback of enthusiastic witnesses, and strangely enough, the positive feedback of persecution. Let us encourage each other, and “so much the more as you see the Day approaching” (10:25). When it comes to love, we want a “runaway greenhouse effect” as it were. We are to be “shining ever brighter” (Proverbs 4:18). Like the athlete in training, we must progress “from strength to strength” (Psalm 84:7).
Just as God coordinates the abundant cycles in His creation, let us allow him to orchestrate the cycles in which we live. From our daily breath and heartbeat to the decisions we make, words we speak, and adjustments He requires, let it all be in rhythm. May we live in temperance and correction, and yet with “reckless” faith and increasing spiritual momentum.
© 2009 Chard Berndt. All Scriptures NKJV.
Here’s Another
Happy Vernal Equinox everyone! Yeah, spring is coming around again, and my March post has to do with the idea that much of God’s creation goes ’round and ’round. My apologies for the length on this one…I can tell you that next month’s will be about half as long (and a little less technical too). But if you take your time I think you’ll enjoy what I’ve got for you. Thanks for being a part of my little blog world again.