Sync: The Emerging Science of Spontaneous Order – Steven Strogatz

Thoughts: Thoughts: Sync is a solid book - wide-ranging, well-written, and interesting throughout.

(The notes below are not a summary of the book, but rather raw notes - whatever I thought, at the time, might be worth remembering.)

Strogatz, Steven. 2003. Sync: The Emerging Science of Spontaneous Order. Hyperion.

Preface

• 2: “In its most refined form, persistent sync can be spectacular…. The feeling of artistry is heightened when the audience has no idea where the music is going next, or what the next dance move will be. We interpret persistent sync as a sign of intelligence, planning, and choreography.” j: relevant to past discussions about beauty and entropy

I. Living Sync

One: Fireflies and the Inevitability of Sync

• 20: “Simulation is no substitute for math—it [can] never provide a proof—but if [a] conjecture [is] false, simulation [can save] a lot of time by revealing a counterexample. This sort of evidence is extremely valuable in math. When you’re trying to prove something, it helps to know it’s true.”

Two: Brain Waves and the Conditions for Sync

• 54: When looking at a population of oscillators, each of which can adjust the period of their oscillation in response to the behavior of the other oscillators in the population, with a distribution of inherent frequencies, “mutual synchronization is analogous to a phase transition, like the freezing of water into ice…. Similarly [to how water freezes exactly at 0ºC and not gradually as one nears that temperature], sync occurs abruptly, not gradually, as the width of the frequency distribution is lowered through the critical value. In this analogy, the width of the distribution is akin to temperature, and the oscillators are like water molecules. The main difference is that when the oscillators freeze into sync, they line up in time, not space.”
• 69: T. H. Huxley: “the great tragedy of science—the slaying of a beautiful theory by an ugly fact.”

Three: Sleep and the Daily Struggle for Sync

• 92: A human body’s daily temperature cycle interacts with sleep “forbidden zones” - periods, 2-3 hours long, during which a person basically cannot fall asleep. They are “centered about 5 hours after and 8 hours before the time of minimum temperature.”
  • 96: the evening forbidden zone, occurring during the few hours before one usually goes to bed, means it’s more-or-less impossible to entrain to a circadian rhythm that is slightly shorter than 24h
• 98: “Sunlight is by far the most important cue for keeping our bodies in sync…. Specifically, sunlight in the subjective morning speeds the clock up (as if to tell the body, you missed sunrise today so I’ll wake you earlier tomorrow). Sunlight in the middle of the day has little effect on the clock, and sunlight in the evening slows it down.”

II. Discovering Sync

Four: The Sympathetic Universe

• 121: The moon is slightly egg-/cigar-shaped. When the major axis of the moon is not pointing directly toward the earth, tidal forces bring it back into alignment: the earth’s pull on the extra mass in nearby bulge cause it to point towards the earth, while this effect is less on the extra mass in the far-away bulge. This “force imbalance twists [the] moon back into alignment.”

Five: Quantum Choruses

Six: Bridges

• 159: to read at some point maybe: Kurt Wiesenfeld’s 1987 paper on “self-organized criticality,” “an ambitious theory that promised to explain why so many complex systems seem perpetually poised at the brink of catastrophe. The theory was later applied to explain the peculiar statistical patterns observed in mass extinctions, earthquakes, forest fires, and other complex processes in which domino effects propagate through the system, usually producing small cascades and occasionally cataclysmic ones.”
• 160: capacitor: blocks direct current, permits alternating current; vs. inductor: blocks alternating current, permits direct.
• 161: splay states: where multiple oscillators oscillate in the same period, each offset/staggered an equal amount of time from the oscillator previous to them in time. By ordering them in different permutations in space, you get different splay states. “Neuroscientists believe that our memory for odours works something like this, where the oscillators are neurons in the brain’s olfactory bulb, and different patterns of excitation encode different smells.”

III. Exploring Sync

Seven: Synchronized Chaos

• 183: to read at some point maybe: James Gleick’s 1987 Chaos.
• 189-190: in a non-chaotic system, errors grow linearly in time: if you want to make a prediction about a moment in the future that is n times as accurate, make an initial measurement that is n times as accurate, or try to predict a moment ¹/_n times as far into the future. But in a chaotic system, errors grow exponentially: to make a prediction that is n times as accurate, you need an initial measurement that is n^k times as accurate.

Eight: Sync in Three Dimensions

Nine: Small-World Networks

• 241: re statistics about a graph’s connectedness: “Average path length reflects the global structure; it depends on the way the entire network is connected, and cannot be inferred from any local measurement. Clustering reflects the local structure; it depends only on the interconnectedness of a typical neighborhood.”
• 242: when adding random connections to an initial, highly structured graph, “the first few shortcuts drastically [reduce] the size of the world [i.e. the average path length], but [have] far less effect on the clustering.”
• 253: Mark Granovetter, in a radio interview: “the fundamental idea is that your close friends are wonderful for all kinds of things—for giving you support, for helping you when you’re sad, for doing favours that other people wouldn’t do for you—but as sources of information they’re not very good, because your close friends tend to know the same people you know. Whereas people that are just your acquaintances—who might not help you out if you were in desperate trouble—are still better sources of information because they know so many people you don’t know. They’re really your windows on the world, because they’re linked up to different circles from your own.”
  • to read eventually maybe: Granovetter’s paper “The Strength of Weak Ties”.
• 254: to read eventually maybe: László Barabási’s book Linked, about networks and the long-tailed distributions they often lead to.
• 255: “When a physicist sees a power law, his eyes light up. For power laws hint that a system may be organizing itself. They arise at phase transitions, when a system is poised at the brink, teetering between order and chaos. They arise in fractals, when an arbitrarily small piece of a complex shape is a microcosm of the whole. They arise in the statistics of natural hazards—avalanches and earthquakes, floods and forest fires—whose sizes fluctuates so erratically from one event to the next at the average cannot adequately stand in for the distribution as a whole. But despite 20 years of intense effort, the origin of power laws remains controversial.”
• 256: Physicists Ramon Ferrer i Cancho and Richard Solé looked at a large English language corpus and drew edges between words that appeared either next to each other or one word apart. The average path from one word to another in this graph was 2.67 steps(!) - “the linguistic network turned out to be highly organized and far from random, with a clustering of word associations more than 4,000 times greater than that of an equivalent random network.”
• 257: Solé has also “observed that electronic circuits tend to be wired in a small-world fashion. Whether he was analyzing the latest digital microchips or the clunky circuits found in old televisions, he found that all the components were just a few electrical steps from one another, yet they were much more clustered than they would have been in an equivalent random circuit, thanks to the modular design feature by engineering practice. Solé speculates that this kind of layout may have emerged by natural selection, as alternative designs competed for survival over time. In other words, engineers may have unknowingly built the circuits according to small-world principles, by trying to strike the best compromise between low cost and high reliability.”

Ten: The Human Side of Sync