Saturday, April 2, 2016
Late Night Thoughts on Being
We live at a moment of embarrassing riches. I won’t try to catalog our blessings, but I will point out one particular blessing. Someone who wants to think and knows how can find a lot of new ways to think about interesting things, just a few key strokes away. Three online journals deliver bite sized brilliance for free: Aeon, This View of Life, and Nautilus. All three feature consistently provocative, thoughtful, well written, articles that are easily accessible to anyone well-informed enough to be interested.
I have been feasting on the third tonight. Chip Rowe lists the “Top 10 Design Flaws in the Human Body.” These design flaws count, in my view, as some of the strongest pieces of evidence for human evolution. Take number one, for example. The human spine, with its double curve, puts a ridiculous amount of stress on the lower back. My beagle’s spine, by contrast, seems perfectly engineered: a curve that distributes weight evenly between two sets of limbs. Of course, that was the cost of freeing our forelimbs to do such tasks as checking our Facebook pages. Rowe’s opening sentences express what is marvelous about these new journals.
The Greeks were obsessed with the mathematically perfect body. But unfortunately for anyone chasing that ideal, we were designed not by Pygmalion, the mythical sculptor who carved a flawless woman, but by MacGyver.
Yes. The sculptor begins with a hunk of material but designs from scratch. MacGyver has to work with what he has and can exploit but is limited by the design already present in whatever he can pull out of the crashed plane. Like MacGyver, natural selection must rig solutions to present problems. If you wanted to design a bipedal spine from scratch, maybe you could get perfection. If you have to start with a quadruped and raise it off the ground, then compromises are inevitable.
On a level closer to the metaphysical marrow, Gregory Laughlin asks “Can a Living Creature Be as Big as a Galaxy?”
William S. Burroughs, in his novel The Ticket That Exploded, imagined that beneath a planetary surface, lies “a vast mineral consciousness near absolute zero thinking in slow formations of crystal.”
As it happens, I have been reading William S. Burroughs lately‑his letters and his novels Naked Lunch (like Moby Dick, an almost impossible read) and Junky (so good you won’t need heroin). Laughlin thinks Burroughs is onto something. Consider the speed of thought.
The speed of neural transmissions is about 300 kilometers per hour, implying that the signal crossing time in a human brain is about 1 millisecond. A human lifetime, then, comprises 2 trillion message-crossing times (and each crossing time is effectively amplified by rich, massively parallelized computational structuring). If both our brains and our neurons were 10 times bigger, and our lifespans and neural signaling speeds were unchanged, we’d have 10 times fewer thoughts during our lifetimes.
This explains what happened to the Amazing Colossal Man.
If our brains grew enormously to say, the size of our solar system, and featured speed-of-light signaling, the same number of message crossings would require more than the entire current age of the universe, leaving no time for evolution to work its course.
Maybe our brain size, like Baby Bear’s porridge, is just right: bigger than a chimp but small enough to efficiently cohere.
It may be that human brains specifically and living organisms generally must occupy a particular niche in the scale of physics. Allison Eck puts the general point in “How Do You Say “Life” in Physics?”
The arrow of time points in the direction of disorder. The arrow of life, however, points the opposite way. From a simple, dull seed grows an intricately structured flower, and from the lifeless Earth, forests and jungles. How is it that the rules governing those atoms we call “life” could be so drastically different from those that govern the rest of the atoms in the universe?
In 1944, physicist Erwin Schrödinger tackled this question in a little book called What is Life?. He recognized that living organisms, unlike a gas in a box, are open systems. That is, they admit the transfer of energy between themselves and a larger environment. Even as life maintains its internal order, its loss of heat to the environment allows the universe to experience an overall increase in entropy (or disorder) in accordance with the second law.
I was insufficiently amazed by Erwin Schrödinger’s book when first I read it many years ago.
Schrödinger pointed to a second mystery. The mechanism that gives rise to the arrow of time, he said, cannot be the same mechanism that gives rise to the arrow of life. Time’s arrow arises from the statistics of large numbers—when you have enough atoms milling about, there are simply so many more disordered configurations than ordered ones that the chance of their stumbling into a more ordered state is nil. But when it comes to life, order and irreversibility must reign even at the microscopic scale, with far fewer atoms in play. At this scale, atoms don’t come in large enough numbers for their statistics to yield regularities like the second law. A nucleotide—the building block of RNA and DNA, the basic components of life—is, for example, made of just 30 atoms. And yet, Schrödinger noted, genetic codes hold up impossibly well, sometimes over millions of generations, “with a durability or permanence that borders upon the miraculous.”
Living organisms are dependent upon physical processes that are small enough that they are not subject to the laws of averages. This sequestering from larger physical processes is the first sequestering. Before life could begin, there had to be a small space for it to begin. Once it does begin, it sequesters itself in successively more effective ways.
But what can account for the “arrow of life”, that is, the direction of organic processes towards greater order (less entropy)? Well, I guess I’ll blog on that tomorrow.