“In his 1930 text The Principles of Quantum Mechanics, Paul Dirac, a colleague of Heisenberg, contrasted the Newtonian world and the Quantum one: ‘It has become increasingly evident… that nature works on a different plan. Her fundamental laws do not govern the world as it appears in our mental picture in any direct way, but instead they control a substratum of which we cannot form a mental picture without introducing irrelevancies.’
There was a world before Heisenberg and his Inexactness principle. There is a world after Heisenberg. They are the same world but they are different.” —Satyajit Das, in his Edge answer
Every year literary agent John Brockman, who specializes in science authors, sets those authors—and other thinkers he knows—a provocative question, one often concocted by Steve Pinker. We’re then supposed to write short answers, which John publishes on his Edge website and then collects in a book.
This year the question was “What is your favorite deep, elegant, or beautiful explanation?” This again came from Pinker, and it’s a nice one, for most of the answers (at the link) are really thought-provoking and good. (There are few exceptions, which I’ll leave you to find yourself.) It will repay your time to read the answers beneath the titles that intrigue you.
Though John is my agent, I’ve once again been derelict in failing to contribute, perhaps intimidated by all the neuronal power on display. Below are a few answers I especially liked, but have a look at them all. There are 192 of them: a real cerebral salon! (Just do a search on the Edge page to find anyone). Quantum mechanics and evolution dominated this year—no surprise given their explanatory power. I’ve highlighted the ones below because they appeal to my personal tastes. Yours will probably differ.
Andrei Linde: “Why is our universe comprehensible?”
Anthony Garrett Lisi: “An explanation of fundamental particle physics that doesn’t exist yet”
John McWhorter: “How do you get from a lobster to a cat?”
Timmo Hannay: “Feynman’s lifeguard”
Seth Lloyd: “The true rotational symmetry of space”
Gregory Benford: “Beautiful, unreasonable mathematics”
Karl Sabbagh: “The Oklo Pyramid”
Gerald Smallberg: “The wizard of I”
Alvy Ray Smith: “Why do movies move?”
Marcel Kinsbourne: “How to have a good idea”
Richard Dawkins: “Redundancy reduction and pattern recognition”
Elizabeth Dunn: “Why we feel pressed for time”
Todd C. Saktor: “The elementary particle of memory”
Freeman Dyson:”Explaining how two systems of this world can both be true”
Shing-tung Yau: “A sphere” (I share his dilemma)
Leonard Susskind: “Boltzmann’s explanation of the second law of thermodynamics”
Lawrence Krauss: “The 19th century explanation of the remarkable connection between electricity and magnetism”Tor Nørretranders: “The production of antibodies”Steven Pinker: “Evolutionary genetics explains the conflicts of human social life”. This is a spirited defense of evolutionary psychology, and you should read it even if you’re an EP opponent.Peter Wolt: “The mysterious coherence between fundamental physics and mathematics”Jared Diamond: “The origins of biological electricity”
Finally, although I knew the tale told by Dan Dennett in his answer: “Why some sea turtles migrate,” many readers might not be familiar with his example, so I’m recounting his answer in full. Note that Dan’s facts about the turtles appear incorrect, but the lesson is still useful:
Why Some Sea Turtles Migrate
My choice is an explanation that delights me. It may be true and may be false—I don’t know, but probably somebody who reads Edge will be able to say, authoritatively, with suitable references. [JAC: I oblige Dan below.] I am eager to find out. I was told some years ago that the reason why some species of sea turtles migrate all the way across the South Atlantic to lay their eggs on the east coast of South America after mating on the west coast of Africa is that when the behavior started, Gondwanaland was just beginning to break apart (that would be between 130 and 110 million years ago), and these turtles were just swimming across the narrow strait to lay their eggs. Each year the swim was a little longer—maybe an inch or so—but who could notice that? Eventually they were crossing the ocean to lay their eggs, having no idea, of course, why they would do such an extravagant thing.
What is delicious about this example is that it vividly illustrates several important evolutionary themes: the staggering power over millions of years of change so gradual it is essentially unnoticeable, the cluelessness of much animal behavior, even when it is adaptive, and of course the eye-opening perspective that evolution by natural selection can offer to the imagination of the curious naturalist. It also demonstrates either the way evolutionary hypotheses can be roundly refuted by discoverable facts (if it is refuted) or the way those hypotheses can be supported by further evidence (if in fact it is so supported).
An attractive hypothesis, such as this, is the beginning, not the end, of the inquiry. Critics often deride evolutionary hypotheses about prehistoric events as “just-so stories,” but as a blanket condemnation this charge should be rejected out of hand. Thousands of such hypotheses—first dreamt up on slender evidence—have been tested and confirmed beyond a reasonable doubt. Thousands of others have been tested and disconfirmed. They were just-so stories until they weren’t, in other words. That’s the way science advances.
I have noticed that there is a pattern in the use of the “just-so story” charge: with almost no exceptions it is applied to hypotheses about human evolution. Nobody seems to object that we can’t know enough about the selective environment leading to whales or flowers for us to hold forth so confidently about how and why whales and flowers evolved as they did. So my rule of thumb is: if you see the “just-so story” epithet hurled, look for a political motive. You’ll almost always find one. While it is no doubt true that some evolutionary psychologists have advanced hypotheses about human evolution for which there is still only slender supporting evidence, and while it is also no doubt true that some evolutionary psychologists have been less than diligent in seeking further evidence to confirm or disconfirm their favorite hypotheses, this is at most a criticism of the thoroughness of some researchers in the field, not a condemnation of their method or their hypotheses. The same could be said about many other topics in evolutionary biology.
I think Dan’s referring here to the story published by Bowen, Meylan, and Avise in Proceedings of the National Academy of Sciences in 1989 (reference below, download free). Sadly, that paper appears to disprove the facts and explanation stated by Dan above.
Individuals from one colony of green sea turtles (Chelonia mydas) feed on the coast of Brazil, but nest not in Africa, but on Ascension Island, in the south-central Atlantic 2000 km (ca. 1300 miles) from the feeding grounds. How this happened was originally suggested by Carr and Coleman in 1974 (reference below, at link). They noted that as Africa and South America spread apart, a series of islands formed at the mid-Atlantic ridge where sea-floor spreading occurred, driving the continents apart. As the sea-floor spread, the new islands eroded beneath the sea, but new ones formed on the ridge as Africa and Brazil moved farther and farther away.
Carr and Colman suggested that turtles were originally breeding on the coast of northern South America and feeding offshore, and some of them originally found their way to a newly-formed volcanic island in the narrow channel between Africa and South America, nesting on the isolated beaches there. As that island eroded, they moved a bit farther away from South America to a newer island, and so on and so on, to island after eroding island, until they were breeding thousands of kilometers from where they fed.
They added that the turtles were genetically imprinted on the migration route, which kept them heading in the same direction to breed for millions of years. It’s a nice story.
But this beautiful theory was killed by an ugly fact: Bowen et al.’s PNAS paper showed that while natal homing is suggested among present-day colonies by fixed differences in DNA sequences of turtles from different rookeries, the divergence in DNA sequence between the Ascension rookery and other Atlantic rookeries is nowhere near as large as that expected had the Ascension turtle been isolated for millions of years. Bowen et al. suggest, in fact, that the colonization of Ascension is far more recent, and homing behavior is not genetically programmed but learned from environmental cues.
Why the descendants of those colonists go so far to feed is, of course, another question, though those might be the closest feeding grounds.
Perhaps Dan is referring to some other migration route, but I’m pretty sure that this is the story he’s recounting, and I’m not aware of any turtle that migrates all the way across the Atlantic Ocean.
Here, from Aimo Through the Years, is a female turtle on Ascension dragging herself back to the ocean after laying her eggs in the sand. (I’ve seen this in Costa Rica, and it’s a painfully slow process.) It’s impossible to watch the entire operation without feeling empathy for these beautiful animals. Females even appear to be crying as they oviposit, exuding liquid from their eyes to keep the sand out.
Here, from Kelso’s Corner, is Ascension Island on the mid-Atlantic ridge:
h/t: Ben Goren for directing me to the Edge question site
Bowen, B. W., A. B. Meylan, and J. C. Avise. 1989. An odyssey of the green sea turtle: Ascension Island revisited. Proc Natl Acad Sci U S A. 86: 573–576.
Carr, A. R. and P. J. Coleman. 1974. Seafloor spreading and the odyssey of the green turtle. Nature 349:128-130