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segunda-feira, dezembro 25, 2006

Excêntricos (II): Luca Turin

Ok, ok, sim eu li o livro do Luca Turin. Achei que, se ele estiver certo, sua história seria mais um exemplo interessante da afirmativa Kuhn-Plankiana de que novas teorias só vencem quando os defensores das velhas teorias envelhecem e morrem (na verdade, acho mais plausível que a mudança se de via comportamento de manada, ou seja, quando coletivamente os cientistas começam a ponderar, de forma agnóstica, os ganhos e perdas de uma mudança de posição. Ou seja, para se fazer pesquisa sobre uma dada teoria, não é necessário acreditar nela, mas apenas ficar motivado por sua possível fertilidade, facilidade de ataque de problemas e obtenção de resultados (mesmo negativos), financiamento, recompensa para quem chegar primeiro (ou em segundo) caso a teoria esteja correta. Tudo isso, claro, fica facilitado se alguns lideres científicos (os caras do extremo da distribuição de status científico e intelectual -os dois status não necessariamente coexistem) derem seu aval sinalizando aos jovens pesquisadores que aquele tópico é quente. Ah sim, essa sinalização também tem sido feita, ultimamente, por jornalistas científicos da Nature e Science...

Entretanto, usando os critérios usuais de detecção de cranks, eu fiquei achando que Luca Turin certamente apresenta todos os sintomas de ser um crank segundo Gardner, a saber:

(1) First and most important of these traits is that cranks work in almost total isolation from their colleagues. Cranks typically do not understand how the scientific process operates that they need to try out their ideas on colleagues,
attend conferences and publish their hypotheses in peer-reviewed journals before announcing to the world their startling discovery. Of course, when you explain this to them they say that their ideas are too radical for the conservative scientific establishment to accept.

(2) A second characteristic of the pseudo-scientist, which greatly strengthens his isolation, is a tendency toward paranoia, which manifests itself in several ways:(a) He considers himself a genius. (b) He regards his colleagues, without exception, as ignorant blockheads.... (c) He believes himself unjustly persecuted and discriminated against. The recognized societies refuse to let him lecture. The journals reject his papers and either ignore his books or assign them to "enemies" for review. It is all part of a dastardly plot. It never occurs to the crank that this opposition may be due to error in his work.... (d) He has strong compulsions to focus his attacks on the greatest scientists and the best-established theories. When Newton was the outstanding name in physics, eccentric works in that science were violently anti-Newton. Today, with Einstein the father-symbol of authority, a crank theory of physics is likely to attack Einstein.... (e) He often has a tendency to write in a complex jargon, in many cases making use of terms and phrases he himself has coined.


Outro sintoma é publicar suas idéias em livros de divulgação dirigidos ao público. Sim, eu sei, Galileu apresentava todos esses sintomas também... Afinal, escrever livros populares em italiano corrente sem peer review em vez de usar a linguagem acadêmica internacional da época (latim) me parece muito suspeito. Mas quem disse que Galileu não era, psicologicamente, um crank?
A teoria de Turin, chamada de Vibratory Theory of Smell (hummm, vibratory é uma palavra bem crank) consta da lista de teorias pseudocientíficas da Wikipédia. Talvez isto se deva devido aos resultados negativos referentes às previsões de Turin encontrados por Leslie Vosshall, da Universidade de Rokfeller, em 2004, comentadas aqui:
(...) Turin never undertook a series of experiments that he said, in a theoretical paper, would prove his theory. “Since Turin’s theory was based solely on his unverified reports about the smell of certain odorants, the scientific community rejected it as a universal theory of smell based on one man’s olfactory impressions,” says postdoc Andreas Keller, first author of a report on the research published in the April issue of Nature Neuroscience. A few months ago, Keller and Vosshall — who normally study olfaction in fruit flies — decided to conduct the human studies that Turin never did.

“This is a theory that has been universally rejected by every scientist, so you might ask why we bothered,” Vosshall says. “We felt that his theory has been given, by virtue of press coverage, some degree of credibility although it was never been put up to scientific scrutiny.”

(...) “In order for science to have integrity, you have to do studies properly. You can’t just sniff the substances yourself, decide in advance what the answer is supposed to be, confirm by testing it yourself and then publish a paper,” says Vosshall. “I did the boring work of actually doing Turin’s experiments and showing what the real answer is,” says Keller, with a laugh. Because the study was not designed to prove either theory, the results say only how smell doesn’t work. They don’t bring us any closer to knowing how it does work. “This is a paper of solely negative results,” Vosshall says. “We didn’t disprove the vibration theory, we just didn’t find anything to support it. The results show that molecular vibrations alone cannot explain the perceived smell of a chemical. And while all of our data are consistent with the shape theory, they don’t prove the shape theory.”
Qual então foi a minha surpresa em ver esses dias essa nota na Nature News:


December 7, 2006


Rogue theory of smell gets a boost
Physicists check out a bold hypothesis for how the nose works.
by Philip Ball
http://www.nature.com/news
RELATED SITES

Could humans recognize odor by phonon assisted tunneling?

A controversial theory of how we smell, which claims that our fine sense of odour depends on quantum mechanics, has been given the thumbs up by a team of physicists.
Calculations by researchers at University College London (UCL) show that the idea that we smell odour molecules by sensing their molecular vibrations makes sense in terms of the physics involved.
That's still some way from proving that the theory, proposed in the mid-1990s by biophysicist Luca Turin, is correct. But it should make other scientists take the idea more seriously.
"This is a big step forward," says Turin, who has now set up his own perfume company Flexitral in Virginia. He says that since he published his theory, "it has been ignored rather than criticized."

Physics, abstractphysics/0611205
From: Andrew Horsfield [view email]
Date: Wed, 22 Nov 2006 08:04:17 GMT (22kb)


Could humans recognize odor by phonon assisted tunneling?
Authors: Jennifer C. Brookes, Filio Hartoutsiou, A. P. Horsfield, A. M. StonehamComments: 10 pages, 1 figureSubj-class: Biological Physics
Our sense of smell relies on sensitive, selective atomic-scale processes that are initiated when a scent molecule meets specific receptors in the nose. However, the physical mechanisms of detection are not clear. While odorant shape and size are important, experiment indicates these are insufficient. One novel proposal suggests inelastic electron tunneling from a donor to an acceptor mediated by the odorant actuates a receptor, and provides critical discrimination. We test the physical viability of this mechanism using a simple but general model. Using values of key parameters in line with those for other biomolecular systems, we find the proposed mechanism is consistent both with the underlying physics and with observed features of smell, provided the receptor has certain general properties. This mechanism suggests a distinct paradigm for selective molecular interactions at receptors (the swipe card model): recognition and actuation involve size and shape, but also exploit other processes.
Full-text: PostScript, PDF, or Other formats
Update: O artigo será publicado pelo Physical Review Letters, ver link aqui.

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