Saturday, February 16, 2019

Nature's got rhythm - it slows down entropy

kw: book reviews, nonfiction, natural history, mathematics, synchronicity, sync

When you view this video, most of the language you hear is Malay. In parts of Asia, and in the Great Smoky Mountains in the U.S., certain species of firefly synchronize their flashing. Why? You'll get part of the answer from reading Sync: How Order Emerges from Chaos in the Universe, Nature, and Daily Life, by Steven Strogatz.

As a professor of applied mathematics, Dr. Strogatz has studied sync for most of his career. As a freshly-minted college graduate, he chanced to get a book by Art Winfree (deceased), who became a mentor to him and kick-started his lifelong fascination with synchronicity (sync), and how it is found throughout nature, both in living and nonliving systems.

When our brain forms a lasting memory, a scattering of neurons that reach from end to end of the brain will pulse in sync for a moment. For some reason, memories we aren't destined to hang onto cause a less wide-ranging burst of activity. What little we so far know about this is discussed in Chapter 10, "The Human Side of Sync". The synced fireflies seen in the video above, and theories for the phenomenon, are discussed in the opening chapter, "Fireflies and the Inevitability of Sync." We respond strongly to sync, as evidenced by our love of dance, singing together, and applauding of cheering together. "The Wave" in a sports arena is a traveling sync phenomenon. I've experienced The Wave running around a stadium six or seven times before fading out.

Our "body clock", circadian rhythm, seems to be rooted in a clock that resides in every cell of our body. It typically runs on a 25-hour cycle and is reset by daylight. Experiments with people spending months in "time free" areas like caves or specially built rooms, who were given no clues about what day or time it was (and who frequently went rather crazy), elucidated this chart:

Our body temperature follows a pretty strict daily curve usually peaking at or just below the proverbial 98.6° (actually chosen because it is exactly 37°C, though that is a tad warm) about sundown, and dipping as much as 1.5°F (0.8°C) to a low a few hours before sunrise. BTW, my daily high is seldom above 98°F.

This chart gives support to the siesta habit in some cultures (not only Latino), and to the big spike in "inattentive driving" accidents during the Zombie Zone after midnight.

This chart is averaged. Some people's cycle runs later, some earlier. A friend of mine cannot sleep past 3:00 AM, so he must hit the sack between 7:00 and 8:00 PM to get a full night's rest. Teenagers are frequently "owls", needing to sleep until at least 9:00 AM, even though most high schools start their day more than an hour earlier (taking care of the parents' work day requirements); so our kids are sleepy in class and learn less. This is in part why homeschoolers learn better, on average. Their parents start the learning day later.

Nonliving systems also synchronize. A few centuries ago, Christian Huygens, recuperating from illness, noticed that two clocks hanging on his bedroom wall were ticking in sync. Here, they were in exactly opposite phases: one would tick when the other went tock. There is an episode of  Mythbusters focused on putting hundreds of metronomes on a platform sitting on rollers, showing that, if set to (nearly) the same frequency, they gradually all sync up and tick together. A pair of tiny moons in orbit around Saturn was found to be sharing an orbit in which one almost catches up with the other, then both shift—one a little inward and the other a little outward—so that they move apart and swap velocities so that the formerly slow one will begin to get ahead until it was the one catching up. The two moonlets never touch. I find them similar to Huygens's clocks.

What is going on here? It seems that nature loves sync. A few decades ago I read an essay, based on a physics professor's lecture, called "Nature's Hangups". It illustrated a number of the things that happen in nature to keep everything from just falling to a center and eliminating itself in a big "whooomph". Sync had a lot to do with it. Near the end of Sync, the same principle is mentioned, using an eloquent image of complex systems taking advantage of entropy to form local pockets of decreased entropy, things that we call living beings, crystals, and solar systems. Sync describes the formation of "time crystals", the regular pulse of a natural system, analogous to the regular array of atoms of molecules in a mineral crystal.

Phenomena as disparate as our heartbeat, the swirling of flocks of starlings or schools of fishes, the aforementioned synced fireflies, seizures induced by repetitive flashes (I've been knocked out cold by a rising sweep of bright flashes), and the Kirkwood Gaps in the asteroid belt (orbits in sync with Jupiter), all have related mathematical descriptions, revealing an underlying tendency in nature to sync things up. In later chapters, starting with 7, "Synchronized Chaos", we find that even wildly gyrating "chaotic" systems (in the mathematical sense) can synchronize themselves, which may lead to improved ways to encrypt communications.

Dr. Strogatz is a mathematician. He is also one of the great explainers of recent generations. He manages to discuss and describe many highly mathematical subjects, and make them at least conceptually understandable, without using a single equation. Sync is literally keeping you alive, and his book tells how.

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