The Fermi-Pasta-Ulam-Tsingou problem: A foray into the beautifully simple and the simply beautiful

by Ashutosh Jogalekar

In November 1918, a 17-year-student from Rome sat for the entrance examination of the Scuola Normale Superiore in Pisa, Italy’s most prestigious science institution. Students applying to the institute had to write an essay on a topic that the examiners picked. The topics were usually quite general, so the students had considerable leeway. Most students wrote about well-known subjects that they had already learnt about in high school. But this student was different. The title of the topic he had been given was “Characteristics of Sound”, and instead of stating basic facts about sound, he “set forth the partial differential equation of a vibrating rod and solved it using Fourier analysis, finding the eigenvalues and eigenfrequencies. The entire essay continued on this level which would have been creditable for a doctoral examination.” The man writing these words was the 17-year-old’s future student, friend and Nobel laureate, Emilio Segre. The student was Enrico Fermi. The examiner was so startled by the originality and sophistication of Fermi’s analysis that he broke precedent and invited the boy to meet him in his office, partly to make sure that the essay had not been plagiarized. After convincing himself that Enrico had done the work himself, the examiner congratulated him and predicted that he would become an important scientist.

Twenty five years later Fermi was indeed an important scientist, so important in fact that J. Robert Oppenheimer had created an entire division called F-Division under his name at Los Alamos, New Mexico to harness his unique talents for the Manhattan Project. By that time the Italian emigre was the world’s foremost nuclear physicist as well as perhaps the only universalist in physics – in the words of a recent admiring biographer, “the last man who knew everything”. He had led the creation of the world’s first nuclear reactor in a squash court at the University of Chicago in 1942 and had won a Nobel Prize in 1938 for his work on using neutrons to breed new elements, laying the foundations of the atomic age. Read more »

Creationism as conspiracy theory – the case of the peppered moth

Addendum: On the day this item was posted, a school board member in Nebraska used slides of Well’s Icons of Evolution to argue that the school should teach “the evidence for and against neo-Darwinian evolution;” details here and here.

by Paul Braterman

Lichte_en_zwarte_versie_berkenspanner

Comparison of carbonaria and typica mounted against post-industrial treetrunk, 2006. Licenced under GFDL by the author, Martinowski at nl.wikipedia. [Click image to enlarge.]

The peppered moth provides a textbook example of industrial melanism and its reversal. Once a classroom classic, then much criticised, and finally rehabilitated through further observation, the story also shows how real science works. The response of the creationist and “Intelligent Design” community provides a textbook example of a conspiracy theory in action, with cherry-picked quotations, allegations of collusion and fraud, and refusal to acknowledge new evidence.

This moth comes in two main varieties, mottled pale (typica), and dark-coloured (carbonaria). The dark form was first noticed, as a rarety, in 1848. Then came widescale industrialisation and grime. By 1895, 98% of the peppered moths in Manchester were dark, and in 1896 it was first suggested that this was a camouflage effect; typica is well concealed against a pre-industrial treetrunk, with its mottling of lichen, but against a sooty background it is an obvious meal for any passing bird. J.B.S. Haldane, in 1924, applied his new methods of quantitative genetics to the speed of such changes, and inferred that carbonaria must have possessed something like 50% per generation advantage over its pallid competitor. An extreme case of Darwinian evolution.

(Let me define that term, since for their own reasons creationists habitually equate all modern biology with Darwin. Darwinian evolution requires just three components; inheritable variation within a population, competition between its members to survive and reproduce, and a difference in fitness between variants. Fitness, here, is simply the ability to survive and have offspring that are themselves fit. This then leads to the evolution of a population in which the variations that confer fitness have become more common. We now know, as Darwin did not, that the inheritable variation corresponds to differences in genes, and that mutations, arising from gene copying errors, give rise to an ongoing supply of new variations. That’s it.)

In the 1950s, Bernard Kettlewell, medical student turned naturalist, carried out a set of direct experiments to test the suggestion that industrial melanism was the result of selective predation. He released large numbers of moths, a mixture of typica and carbonaria, in both polluted and unpolluted woodlands. As expected if the predation-selection mechanism is operating, the survival rate was greater for typica in clean environments, while the opposite applied in environments that were polluted. Kettlewell then persuaded Niko Tinbergen to film the actual process in both kinds of environment. Tinbergen later shared the 1973 Nobel Prize for his work on supernormal stimuli (exaggerated forms preferred to the real ones), along with Konrad Lorentz (filial imprinting) and Karl von Frisch (bee signalling).

Subsequent decades saw the passage of clean air acts, the washing clean of trees by unpolluted rainwater and the return of lichens, and a recovery of the numbers of typica at the expense of carbonaria.

So here we had the clearest possible example of Darwinian evolution in action. Variation dependent on a single gene; a selection pressure, namely predation by birds; an evolved response, namely camouflage; and a change in the direction of evolution with circumstances as camouflage favoured first one variant, then the other. Or so it seemed.

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And Another ‘Thing’ : Sci-Fi Truths and Nature’s Errors

by Daniel Rourke

In my last 3quarksdaily article I considered the ability of science-fiction – and the impossible objects it contains – to highlight the gap between us and ‘The Thing Itself’ (the fundamental reality underlying all phenomena). In this follow-up I ask whether the way these fictional ‘Things’ determine their continued existence – by copying, cloning or imitation – can teach us about our conception of nature.

Seth Brundle: What’s there to take? The disease has just revealed its purpose. We don’t have to worry about contagion anymore… I know what the disease wants.

Ronnie: What does the disease want?

Seth Brundle: It wants to… turn me into something else. That’s not too terrible is it? Most people would give anything to be turned into something else.

Ronnie: Turned into what?

Seth Brundle: Whaddaya think? A fly. Am I becoming a hundred-and-eighty-five-pound fly? No, I’m becoming something that never existed before. I’m becoming… Brundlefly. Don’t you think that’s worth a Nobel Prize or two?

The Fly, 1986

In David Cronenberg’s movie The Fly (1986) we watch through slotted fingers as the body of Seth Brundle is horrifically transformed. Piece by piece Seth becomes Brundlefly: a genetic monster, fused together in a teleportation experiment gone awry. In one tele-pod steps Seth, accompanied by an unwelcome house-fly; from the other pod emerges a single Thing born of their two genetic identities. The computer algorithm designed to deconstruct and reconstruct biology as pure matter cannot distinguish between one entity and another. The parable, as Cronenberg draws it, is simple: if all the world is code then ‘all the world’ is all there is.

Vincent Price in 'The Fly', 1958Science fiction is full of liminal beings. Creatures caught in the phase between animal and human, between alien and Earthly, between the material and the spirit. Flowing directly from the patterns of myth Brundlefly is a modern day Minotaur: a manifestation of our deep yearning to coalesce with natural forces we can’t understand. The searing passions of the bull, its towering stature, are fused in the figure of the Minotaur with those of man. The resultant creature is too fearsome for this world, too Earthly to exist in the other, and so is forced to wander through a labyrinth hovering impossibly between the two. Perhaps Brundlefly’s labyrinth is the computer algorithm winding its path through his genetic code. As a liminal being, Brundlefly is capable of understanding both worlds from a sacred position, between realities. His goal is reached, but at a cost too great for an Earthly being to understand. Seth the scientist sacrifices himself and there is no Ariadne’s thread to lead him back.

In her book on monsters, aliens and Others Elaine L. Graham reminds us of the thresholds these ‘Things’ linger on:

“[H]uman imagination, by giving birth to fantastic, monstrous and alien figures, has… always eschewed the fiction of fixed species. Hybrids and monsters are the vehicles through which it is possible to understand the fabricated character of all things, by virtue of the boundaries they cross and the limits they unsettle.”

Elaine L. Graham, Representations of the Post/Human

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