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The Curious Wavefunction


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Chemistry and Biology: Kuhnian or Galisonian?

The views expressed are those of the author and are not necessarily those of Scientific American.


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Peter Galison who has emphasized the dominance of experimental techniques in engineering scientific revolutions (Image: BNL).

Freeman Dyson has a perspective in this week’s Science magazine in which he provides a summary of a theme he has explored in his book “The Sun, the Genome and the Internet”. Dyson’s central thesis is that scientific revolutions are driven as much or even more by tools than by ideas. This view runs somewhat contrary to the generally accepted belief regarding the dominance of Kuhnian revolutions – described famously by Thomas Kuhn in his seminal book “The Structure of Scientific Revolutions” – which are engineered by ideas and shifting paradigms. In contrast, in reference to Harvard university historian of science Peter Galison and his book “Image and Logic”, Dyson emphasizes the importance of Galisonian revolutions which are driven mainly by experimental tools.

As a chemist I find myself in almost complete agreement with the idea of tool-driven Galisonian revolutions. Chemistry as a discipline rose from the ashes of alchemy, a thoroughly experimental activity. Since then there have been four revolutions in chemistry that can be called Kuhnian. One was the attempt by Lavoisier, Priestley and others at the turn of the 17th century to systematize elements, compounds and mixtures to separate chemistry from the shackles of alchemical mystique. The second was the synthesis of urea by Friedrich Wohler in 1828; this was a paradigm shift in the true sense of the term since it placed substances from living organisms into the same realm as those from non-living organisms. The third revolution was the conception of the periodic table by Mendeleev, although this was more of a classification akin to the classification of elementary particles by Murray Gell-Mann and others during the 1960s. A minor revolution accompanying Mendeleev’s invention that was paramount for organic chemistry was the development of the structural theory by von Leibig, Kekule and others which led the way to structure determination of molecules. The fourth revolution was the application of quantum mechanics to chemistry and the elucidation of the chemical bond by Pauling, Slater, Mulliken and others. All these advances blazed new trails, but none were as instrumental or overarching as the corresponding revolutions in physics by Newton (mechanics), Carnot, Clausius and others (thermodynamics), Maxwell and Faraday (electromagnetism), Einstein (relativity) and Einstein, Planck and others (quantum mechanics).

Why does chemistry seem more Galisonian and physics seem more Kuhnian? One point that Dyson does not allude to but which I think is cogent concerns the complexity of the science. Physics can be very hard, but chemistry is more complex in that it deals with multilayered, emergent systems that cannot yield themselves to reductionist, first principles approaches. This kind of complexity is also apparent in the branches of physics typically subsumed under the title of “many-body interactions”. Many-body interactions range from the behavior of particles in a superconductor to the behavior of stars condensing into galaxies under the influence of their mutual gravitational interaction. There are of course highly developed theoretical frameworks to describe both kinds of interactions, but they involve several approximations and simplifications, resulting in models rather than theories. My contention is that the explanation of more complex systems, being less amenable to theorizing, are driven by Galisonian revolutions rather than Kuhnian.

Chemistry is a good case in point. Linus Pauling’s chemical theory arose from the quantum mechanical treatment of molecules, and more specifically the theory of the simplest molecule, the hydrogen molecular ion which consists of one electron interacting with two nuclei. The parent atom, hydrogen, is the starting point for the discipline of quantum chemistry. Open any quantum chemistry textbook and what follows from this simple system is a series of approximations that allow one to apply quantum mechanics to complex molecules. Today quantum chemistry and more generally theoretical chemistry are highly refined techniques that allow one to explain and often predict the behavior of molecules with hundreds of atoms.

And yet if you look at the insights gained into molecular structure and bonding over the past century, they have come from a handful of key experimental approaches. Foremost among these are x-ray diffraction, which Dyson also mentions, and Nuclear Magnetic Resonance (NMR) spectroscopy, also the basis of MRI. It is hard to overstate the impact that these techniques have had on the determination of the structure of literally millions of molecules ranging across an astonishing range of diversity, from table salt to the ribosome. X-ray diffraction and NMR have provided us not only with the locations of the atoms in a molecule, but also with invaluable insights into the bonding and energetic features of the arrangements. Along with other key spectroscopic methods like infrared spectroscopy, neutron diffraction and fluorescence spectroscopy, x-rays and magnetic resonance have not just revolutionized the practice of chemical science but have also led to the most complete understanding we have yet of chemical bonding. Contrast this wealth of data with similar attempts using purely theoretical techniques which can also be used in principle to predict the structures, properties and functions of molecules. Progress in this area has been remarkable and promising, but it’s still orders of magnitude harder to predict, say, the most stable configuration of a simple molecule in a crystal than to actually crystallize the chemical even by trial and error. From materials for solar cells to those for organ transplants, experimental structure determination in chemistry has fast outpaced theoretical prediction.

What about biology? The Galisonian approach in the form of x-ray diffraction and NMR has been spectacularly successful in the application of chemistry to biological systems that culminated in the advent of molecular biology in the twentieth century. Starting with Watson and Crick’s solution of the structure of DNA, x-ray diffraction basically helped formulate the theory of nucleic acid and protein structure. Particularly noteworthy is the Sanger method of gene sequencing – an essentially chemical technique – which has had a profound and truly revolutionary impact on genetics and medicine that we are only beginning to appreciate. Yet we are still far from a theory of protein structure in the form of protein folding; that Kuhnian revolution is yet to come. The dominance of Galisonian approaches to biochemistry raise the question about the validity of Kuhnian thinking in the biological sciences. This is an especially relevant question because the last Kuhnian revolution in biology – a synthesis of known facts leading to a general explanatory theory that could encapsulate all of biology – was engineered by Charles Darwin more than 150 years ago. Since then nothing comparable has happened in biological science; as indicated earlier, the theoretical understanding of the genetic code and the central dogma came from experiment rather than the very general synthesis in terms of replicators, variation and fitness that Darwin put together for living organisms. Interestingly, in his later years (and only a year before the discovery of the structure of DNA) the great mathematician John von Neumann put forward a Darwin-like, general theoretical framework that explained how replication and metabolism could be coupled to each other, but this was largely neglected and certainly did not come to the attention of practicing chemists and biologists.

Dyson’s essay and the history of science does not necessarily assert that the view of science in terms of Kuhnian revolutions is misguided and that in terms of Galisonian revolutions is justified. It’s rather that complex systems are often more prone to Galisonian advances because the theoretical explanations are simply too complicated. Another viewpoint driven home by Dyson is that Kuhnian and Galisonian approaches alternate and build on each other. It is very likely that after a few Galisonian spells a field becomes ripe for a Kuhnian consolidation.

Biology is going to be especially interesting in this regard. The most exciting areas in current biology are considered to be neuroscience, systems biology and genomics. These fields have been built up from an enormous number of experimentally determined facts but they are in search of general theories. However, it is very likely that a general theoretical understanding of the cell or the brain will come from very different approaches from the reductionist approaches that were so astonishingly successful in the last two hundred years. A Kuhnian revolution to understand biology could likely borrow from its most illustrious practitioner – Charles Darwin. One of the signature features of Darwin’s theory is that it seeks to provide a unified understanding that transcends multiple levels of biological organization, from individual to society. Our twenty-first view of biology adds two pieces, genes and culture, to opposite ends of the ladder. It is time to integrate these pieces – obtained by hard, creative Galisonian science – into the Kuhnian edifice of biology.

Ashutosh Jogalekar About the Author: Ashutosh (Ash) Jogalekar is a chemist interested in the history and philosophy of science. He considers science to be a seamless and all-encompassing part of the human experience. Follow on Twitter @curiouswavefn.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. dadster 11:29 pm 12/20/2012

    Quantum Physics has started depending on mathematical models to make further progress because our experimental devices and instruments cannot measure beyond nano or femto levels .The dimension of wave lengths of electromagnetic energy limits our range of measurements directly although , theoretically we can go up to Planck scales and beyond downwards where “reality” ( whatever that is ), lies. In fact, we have no instruments or tools to measure continuity at it’s minutest scales unless we digitalize and consider for
    ” practical ” purposes,approximating continuities to discrete entities . But, nature has no such .imitation in it’s creation of such phenomena as ” life” which is based on continuities and not on discreteness or on quantum jumps.The principles of creation is different from the creed entities. We , who are endowed with an electromagnetic structure (and electromagnetic instruments), can be sensitive to phenomena that are of electromagnetic nature only which we can measure in discrete quantities only. Just like for seeing light ( radiating energy which is a continuous entity ) we need a matter- based structure, ( which are discrete entities ) similarly for seeing or sensing ” life” ( a continuous entity ) we need material body ( a discrete matter- structure ) . But that doesn’t make “life” and matter , the same or life is emerging out of matter . It would be like saying that radiating energies are “emergent” from discrete matter . Radiating energy is more fundamental than or at least as fundamental as matter itself . Similarly ,
    “life” ( or, bio- energy ) is a fundamental entity and NOT an emergent quality of certain configurations of matter .The physicists ( who want to corner maximum reaserch grants to their field ) want to make it so . They tried it on chemistry and to certain limits succeeded . They are trying nit now on bio- energies . Unfortunately , with whatever “physical- chemistry” and “bio- chemistry” they tried to produce even a single living cell in the lab , they could not succeed although nature so prolifically and abundantly produce “life” and sustain it too every nano- second ! It’s time that biologists , peel themselves off the strangle- hold of physicists and physic- chemists and , form their own paradigms suitable to deal with continuities and bio- energies which are radically distinct from electromagnetic energies as gravity is ( by the way it’s interesting to watch the pathetic efforts of hard- core physicists to rope in continuous gravity into the matter- field by discretizing ( “graviton-ing) it in vain. Gravity is an energy out of “space- time distortions” ( an image concocted to give form to a mathematical model ), and not matter- based like some aspects of electromagnetism is.

    Perhaps it’s time to consider three distinct energy- systems (bio- energy , electromagnetic energy, matter- energy ) which might have the same origin or which might be three manifestations of the same energy , say of “vacuum
    energy ” . These three different- looking energy forms have been brought into being simultaneously out of spontaneous random fluctuations of vacuum energy . Although the concept of vacuum energy itself sprang out of physical paradigms , till bio- sciences anvil out their own independent paradigm shift we may have to stand on the shoulders of physical paradigms , TEMPORARILY .

    The point that’s being made is that bio- energies are not emergent energies, but are fundamental energies . This is emphasized by the recent cambridge university quantum scientists who proposed that its NOT quarks , or strings or protons or electrons which are the fundamental entities that our universe is made of but the fundamental entity with which our universe is made of is “INFORMATION ” ( see ” Pandoras box ” article ).
    Second point being made is that bio- scientists must find their own paradigms to describe bio- energies ,eschewing the paradigms created by physics. Bio- scientists dealing with bio- energies might have to invent their own abstractions ( instead of banking on physical- mathematics ) to describe the characteristics of bio- energy .

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