Showing posts with label Karl Popper. Show all posts
Showing posts with label Karl Popper. Show all posts

Tuesday, December 11, 2012

Magicians reveal what the world's all about

For several years, I've been fascinated by the popular books of three physicists: Brian Greene, David Deutsch and Lawrence Krauss.

Funnily enough, although the three of them are writing about the same general subject—our state-of-the-art understanding of the nature of the universe—they rarely, if ever, get around to handling the same questions in comparable, if not similar, fashions. Moreover, in their latest books, they hardly even refer to one another's work.

It's easy to understand superficially why Greene, Deutsch and Krauss don't seem to have a lot to say to one another. Greene has been reputed for a long time as an adept of string theory, and there's no reason to imagine that the other two physicists are particularly keen on this theory. Earlier this year, Krauss became widely known through his presentation of an esoteric explanation of how the ultimate "free lunch"—obtaining something from nothingness—is a perfectly plausible phenomenon at a cosmic level.

As for the 59-year-old Oxfordian David Deutsch, he comes through to me as the most philosophical member of the trio. Indeed, he offers us a multiverse view of existence that is totally amazing. As in his first book, The Fabric of Reality, Deutsch pursues in The Beginning of Infinity his quest for a Theory of Everything inspired by the work of a somewhat heteroclite foursome: Karl Popper (epistemology), Hugh Everett (multiverse theory), Alan Turing (computation) and Richard Dawkins (evolution). Indeed, between the Popperian explanations of knowledge, the connotations of quantum theory leading to the existence of multiple universes, the vast theories of classical computing put forward by Turing (which are no doubt sufficient to handle, not only the DNA computer responsible for replication and life, but also the phenomena of neuronal computing) and finally the processes of Darwinian evolution and genetics so brilliantly presented by Dawkins, most observers would agree that we've no doubt covered many of the basic essentials of a scientific outlook on reality. Deutsch himself refers to these four grand dimensions of his global philosophical approach as strands (a word I like, which evokes weaving a fabric).

A few weeks ago, I was excited to learn that Deutsch has been working on a kind of fifth strand, of a subterranean nature, which he calls constructor theory. If you've got 47 minutes of free time, I urge you to click here to listen to Deutsch himself presenting this work. Basically, it's a matter of trying to understand why certain things are possible (even though they may have never actually happened yet) whereas countless other potential events are impossible because certain laws of physics have "blacklisted" them forever. In other words, he has enhanced astronomically the sense of the concept of possibility, to the point of claiming that anything and everything is strictly possible... provided only that we know of no law of physics that forbids such a happening, and therefore renders it impossible. Deutsch draw our attention to the strict binarity of the situation. Between the impossible (ruled out by physics) and the possible, there is no third way out. On the one hand, nothing—not even the most extravagant events—should be branded as theoretically impossible unless we are already aware of a law of physics that forbids such things. On the other hand, everything else should be thought of as theoretically possible.

In his eagerness to point out the counterintuitive nature of this thinking, Deutsch hit upon an amusing easy-to-grasp example, which goes straight to the heart of my Antipodes blog. Most of us agree that people on the other side of the planet Earth are in an upside-down position with respect to us, and vice versa.

That old Epinal image is funny but quite silly, of course, because nobody really believes that Antipodeans get around on their hands, with their Hobbit-like feet stretching towards the heavens. But are we truly ready to admit that the heads of Antipodeans point constantly in the opposite direction to our own heads? If technology were to offer me a magical real-time closeup view of Antipodeans, in strict conformity with our mutual orientations, in the same way that binoculars enable me to observe distant objects through my bedroom window, would I not be somewhat surprised to receive upskirt images of Antipodean ladies whose heads appear to be receding upwards into the sky? My surprise (which would be inevitable, I think) would seem to confirm that, to a certain extent, I've never really believed wholeheartedly that the heads of Antipodeans point in the opposite direction to mine. And David Deutsch considers that this mild form of surprise, or doubt, reflects my persistent quest for a third way out, between the possible and the impossible. My scientific culture persuades me that there is no law of physics that would forbid Antipodeans from getting around in an upside-down position with respect to me. So, I conclude that it's perfectly possible for this to be the case. At the same time, I consider that modern laws of celestial mechanics have quashed forever all remnants of flat-Earth theories, meaning that it's unthinkable that the heads of Antipodeans might point in the same direction as mine. And yet I don't seem to have gone one tiny step further and admitted explicitly, in a tangible concrete sense, that people down on the opposite side of the planet are truly presenting me constantly (if only the Earth were transparent) with an upskirt vision of their environment.

What David Deutsch seems to be saying (in a roundabout fashion) is that we would do well to consider, in an equally tangible and concrete sense, that we exist within a multiverse where the quantum effects admitted by today's laws of physics must be thought of, not only as possible happenings, but as garden-variety aspects of the fabric of everyday reality. And I'm not sure that many of us are prepared, at present, to assimilate profoundly that weird mode of looking at existence. Between archaic fairy tales (often supported by so-called commonsense) and hard state-of-the-art science, we persist in hoping, if not believing, that there must surely be some kind of convenient "third way out".

Saturday, January 21, 2012

Rivers never flow uphill

As a youth in my native Grafton, I didn't think of myself as somebody who might be particularly interested in the flow of rivers. That's because I happened to be living alongside the great Clarence River, which I used to see so regularly (usually from afar) that I finished by no longer noticing it. I had grown up in the aftermath of the tragic December 1943 drowning of 13 boys, junior (cub) members of the local troop of Boy Scouts. As a child of ten or so, I had witnessed the damage waged by the waters of the Clarence in a disastrous flood. Later, I rowed in school races (in "fours") in the shadow of the antique double-decker bridge, over which I used to ride my bicycle regularly.

To paraphrase the well-known forest/trees saying, I simply didn't see the river because of the water. Much later, in Paris, I learned that a river has a left bank and a right bank.

The common-sense adjectives "left" and "right" are so much more tangible, for people living alongside a great river, than the theoretical notions of north and south. So, I had passed my childhood in right-bank Waterview (South Grafton) before moving across to our new left-bank residence in Kent Street (Grafton).

Since arriving here at Choranche, on the edge of the French Alps, I've come to appreciate the sense of the adjectives upstream and downstream. The Bourne flows down from Villard-de-Lans.  Choranche is located on the right bank, and Châtelus on the left. And Pont-en-Royans is a little further downstream. It's a bit like seasons. Back in Australia, I hardly knew what they were all about. These days, at Gamone, they determine my daily existence.

There's another realm, of a theoretical kind, in which we must be aware of the direction of flow. I'm referring to the flow of information and scientific knowledge. Just as rivers never flow in an upstream direction, information and knowledge always flow in a unique direction: downwards from X to Y, say, but never upwards from Y to X.

This was one of the great lessons taught by Karl Popper when he demolished the time-honored but absurd notion that an understanding of the laws of the natural universe can be acquired miraculously when knowledge flows spontaneously, indeed magically, from the natural phenomena being examined by a researcher up into the scientist's mind. This mysterious process, referred to as induction, was a part of established science back in my student days. Since Popper, we realize that a new understanding of the ways in which various natural phenomena unfold can arise in the mind of a brilliant scientist. This knowledge then flows down into other human minds, enabling the newly-imagined explanations to be applied to the natural phenomena that inspired the creative scientist, for verification (best possible case) or for rejection (worst-case scenario).

Two centuries ago, in the domain of the evolution of living organisms, a great and ancient "river" of a physiological kind was thought of as capable, from time to time, of flowing uphill.

 Jean-Baptiste Lamarck considered that a living creature could transmit to its offspring various characteristics acquired during the parent's earthly existence. Take the case of a primitive giraffe, many millennia ago, at a time when giraffes still had relatively short necks, since they could find all the leaves they needed quite close to the ground. Let's suppose that a couple of giraffes were having a serious discussion about the idea of having a baby.

Mr Giraffe: There's only one thing that worries me, dear. Due to global warming, there's no longer any grass around. So, we're forced to eat leaves. But there are fewer and fewer leaves at a low level. Soon, to reach the high leaves and survive, giraffes will need to have longer and longer necks.

Mrs Giraffe: My dear husband, I agree with you entirely. But, if our future baby needs an exceptionally long neck to find food, then we must make sure that he's born with such a neck. There are no two ways about it.

Mr Giraffe: OK, but how can we make sure that his neck will be long enough for him to survive?

Mrs Giraffe: We must pray, my dear husband, and implore our Good Giraffe God to perform a miraculous intervention of genetic engineering.

So, that's what they did. And, soon after, biological information from the parched earth flowed up through the tree trunks, past the bare branches at the bottom of the trees, until it reached the level of the luscious greenery. And, from there, this precious information—dealing primarily with the complex procreative question of how to produce giraffe embryos with long necks—was consumed and digested by Mrs Giraffe… who suddenly felt a glowing long-necked warmth in her womb. The miracle was taking place!

We now know that Lamarckism was totally wrong, but it was never, at any stage, a completely crazy belief. Even today, when tourists halt for a moment alongside the lovely old thatched house in Pont-en-Royans [display], and chat with the village blacksmith and his son, they are invariably impressed by their giant strong hands, which have been  photographed in closeup on countless mobile phones.

Blacksmith: My ancestors have been blacksmiths here at Pont-en-Royans for countless generations, and the blacksmiths' sons and daughters have always married the offspring of other blacksmiths in neighboring villages. And the gnarled hands of our kids, today, reveal the traces of all those centuries of hard work at the forge.

Who could possibly doubt the truth of the good man's words? His strong hands have been shaped, over the centuries, by a mysterious process of divinely-ordained genetic engineering that seems to "understand" that future blacksmiths need to inherit the hands, not merely of their forefathers, but of their forefathers' trade! This knowledge has flowed up from the forge to the uterus of every young lady chosen to become the mother of a future blacksmith. It's all a bit like the Nazarene carpenter's wife, who had received knowledge informing her that she would be giving birth to the Lord.

The only flaw in these nice and convincing tales is that knowledge about a future offspring never needs to flow into an embryo, because the zygote formed from the pair of gametes provided by the parents of a future member of the blacksmith dynasty contains all the information that it is required to forge a new human being. And, if the baby blacksmith looks as if he has inherited gnarled hands, that merely means that at least one of his parents had gnarled hands. And that characteristic had nothing to do with their daily occupations. Even if the latest generations of the baby's ancestors had all decided to transform their ancient forges into tourist boutiques, they would still have been born with gnarled hands. Inheritance specifications never flow upwards from a blacksmith's forge to human parents and their babies. They are transmitted, through chromosomes, from parents down to their offspring. Rivers never flow uphill.

This metaphor of information flow applied both to Karl Popper's views on induction and to Lamarck's views on inheritance was developed at length by David Deutsch, of Oxford.

His article Selfish Genes and Information Flow appeared in the collection entitled Richard Dawkins, How a Scientist Changed the Way We Think, Oxford University Press, 2006.

Tuesday, October 18, 2011

Dawkins gives Miss Anscombe a role

I've just started to read with enthusiasm the latest book by Richard Dawkins, The Magic of Reality, which might be described as a science-oriented picture book for youngsters from 8 to 80. I was amused to discover that the excellent graphic work by Dave McKean depicts a casual conversation between two individuals whom I mentioned six months ago in my blog post entitled Voices from Vienna [display]. I'm referring to the Vienna-born philosopher Ludwig Wittgenstein [1889-1951] and his English disciple Elizabeth Anscombe [1919-2001], who was both a professor of philosophy at Cambridge and a devout Roman Catholic. As I mentioned in that blog post, I had an unexpected opportunity of meeting up with Anscombe in Brittany, at the home of Christine's parents. Members of the Mafart family, including Christine, had frequent contacts with a Dominican priory in Staffordshire known as Spode House, which had also become a regular retreat for the Anscombes.

Here's the drawing of Elizabeth Anscombe and Ludwig Wittgenstein:

Wittgenstein was intrigued by the fact that people had once believed, unanimously, that the Sun went round the Earth. He wondered why this belief was so universal. Anscombe replies—with a massive dose of common sense—that people no doubt found that it looked as if the sun went round the Earth. Wittgenstein hits back with an interesting rhetorical question: "What would it have looked like if it had looked as if the Earth turned on its axis?" In other words, what kinds of visual impressions would have been needed to make people believe spontaneously in a heliocentric theory?

We can find plausible answers in the ordinary experience of air travel. When a plane hits turbulence, passengers never have the impression that it's the Earth and its atmosphere that are being jolted up and down. They're convinced intuitively that the aircraft, which had appeared to be calm and motionless just a minute earlier, is now being shaken by disturbing forces. So, that suggests an answer to Wittgenstein's question. If only the planet Earth were to run into zones of turbulence every now and again, humans would have surely been more ready to feel that their planet was indeed turning on its axis and moving around the Sun.

Air travel provides another striking experience of rapid movement. When an aircraft, preparing to land, plunges down obliquely through wispy layers of cloud, passengers are suddenly made aware of the great speed at which they are moving. Ideally, we might imagine vast rings of dust, orbiting the Sun at roughly the same distance as the Earth, with trajectories that intersect at right angles with ours. Periodically, Earth-dwellers would notice that we were about to run into such a dust ring, since it would be visible in the sky above us. Then, as we whizzed past the dust in a kind of near-miss encounter (hopefully surviving), we might well observe a parallax phenomenon—involving the alignment of the Sun, the dust ring and our planet—suggesting that we are indeed moving around the Sun.

It's preferable, though, to judge such affairs using the methods of scientific reasoning. If Karl Popper had been eavesdropping on the conversation between Ludwig and Miss Anscombe, he might have suggested wisely that they should abandon their jobs in the philosophy department and enroll humbly as science undergraduates…

Thursday, July 26, 2007

Brilliant book

This excellent book by the Oxford physicist David Deutsch came out a decade ago, but I've only just got around to reading it. Seeking to lay the foundations of a vast theory of everything, Deutsch introduces four great domains of knowledge that he refers to as strands:

— Quantum physics

— Epistemology, inspired by the work of Karl Popper

— Theory of computation, inspired by the work of Alan Turing

— Theory of evolution, inspired by the work of Richard Dawkins.

It's rare to find an eclectic author who's prepared to blend such different disciplines into a synthetic whole.