Tuesday, November 30, 2010

Chemists to the rescue?

Here's my Crucible article for the December issue of Chemistry World, which arose when I chaired a recent talk by John Emsley at the RSC.


Can chemists save the world? In his new book, targeted at the 2011 Year of Chemistry and published by the RSC, John Emsley argues in his characteristically inspirational manner that chemical innovations in areas such as biofuels, food production and clean water treatment can deliver the promise of the book’s title: A Healthy, Wealthy, Sustainable World. Emsley makes no apologies about his crusading, even propagandizing agenda, for he rightly points out that many of the biggest global challenges, from climate change to the end of oil, demand the expertise of chemistry, making it potentially the key science of the twenty-first century.

But Emsley concedes that his survey of the wonderful things that chemists have achieved in sustainable technology – converting rapseseed oil to biodiesel or to plastics feedstocks, say – does not look in depth at the economic picture. It’s a frequent and valid objection to technical innovation that it is all very well but how much does it cost in comparison to what we can do already? What’s the financial motivation, say, for China to abandon its abundant coal reserves for biofuels?

There is no blanket answer to such economic conundrums, but common to them all is the question of whether one can rely on market mechanisms to generate incentives for a desirable technology, or whether it should be nurtured by governmental or regulatory intervention. Here, as just about everywhere else right now, the issue is how ‘big’ government should be.

In the wake of the financial crisis, market fundamentalists sound less credible asserting that the market knows best, especially when it comes to societal benefits: the recent boom years were not so much generated by market mechanisms as bought on credit. But it seems equally clear that highly managed economies which subsidize unprofitable enterprises are unsustainable and risk stifling innovation. A middle course has been successfully steered by the German government’s investment in photovoltaic (PV) energy generation, where money for research and breaks for commercial companies are coupled to a concerted effort to build a market for solar power through a feed-in tariff: a guaranteed, highly competitive price for energy generated from solar panels and fed into the grid. This stimulus recognizes that new, desirable technologies may need a hand to get off the ground but need eventually to become independent. With government assistance, the German PV industry has created around 50,000 jobs, brought revenues of €5.6 billion in 2009, and made Germany the largest national source of PV power in the world. By 2020, up to 10 percent of Germany’s energy may be solar.

This is one reason why it is unrealistic to dismiss the prospects for an innovative technology on the basis that its (perhaps less desirable) rivals can currently do things more cheaply. There is a financial component to changing attitudes. Encouraging investment in a fledgling innovation can ultimately lower its price both by enabling efficiencies of scale and by supporting research into cost-cutting improvements. That was amply demonstrated by the Human Genome Project (HGP): the international decision that it was a Good Thing created the opportunity for new sequencing technologies that have reduced the cost and increased the speed of decoding an individual’s genome by orders of magnitude. Simply put, it became financially worthwhile for companies such as Illumina (spearheaded by chemists David Walt and Anthony Czarnik) to devise radical new sequencing methods. As a result, the economic hurdle to realizing the potential medical benefits of genome sequencing was lowered.

At the same time, the race between the publicly funded HGP and a private enterprise by Celera Genomics Inc., the company founded by entrepreneur Craig Venter, shows that competition can accelerate innovation. What’s more, through canny marketing the HGP engineered a favourable climate for investment and public endorsement, creating what economist Monika Gisler at ETH in Zurich and her coworkers have called a ‘social bubble’ [1]. They say that ‘governments can take advantage of the social bubble mechanism to catalyze long-term investments by the private sector, which would not otherwise be supported.’ Of course, there is a fine line between supportive publicity and hype. But this is another reminder that promising new technologies, like children, flourish best when they are neither left to fend for themselves nor mollycoddled indefinitely.

1. M. Gisler, D. Sornette & R. Woodward, preprint http://arxiv.org/abs/1003.2882 (2010).

Monday, November 29, 2010

Flight of fantasy

The chorus of disapproval that greeted Howard Flight’s remark about how cuts in child benefits will encourage ‘breeding’ among the lower social classes (or as Flight called them,‘those on benefits’) has left the impression that such comments are now to be judged in a historical vacuum, purely on the basis of whether or not they accord with a current consensus on ‘appropriateness’, or what some would sneeringly call political correctness. This solipsistic perspective is dangerously shallow.

The media coverage has largely ignored the obvious connection between Flight’s comment and the argument for eugenics originally advanced by Darwin’s cousin Francis Galton in the late nineteenth century and pursued by intellectuals on both the left and the right for a considerable part of the twentieth. Galton voiced explicitly what Flight had at least the restraint (or the nous) only to imply: given the chance, the inferior stock among the lower classes will breed like rabbits and thereby corrupt the species. Galton worried about the ‘yearly output by unfit parents of weakly children who are constitutionally incapable of growing up into serviceable citizens, and who are a serious encumbrance to the nation.’ If the harshness of their circumstances were to be alleviated by welfare, he said, then natural selection would no longer constrain the proliferation of ‘bad genes’ throughout society. In a welfare state, the gene pool of humankind would therefore degenerate.

Some eugenicists felt that the answer was to encourage the genetically superior echelons of society to breed more: educated, middle-class women (who were beginning to appreciate that there might be more to life than endless child-rearing) had a national duty to produce offspring. Some biologists, such as Julian Huxley and J.B.S. Haldane, welcomed the prospect of ectogenesis – gestation of fetuses in artificial wombs – so that it might liberate ‘good’ mothers from that onerous obligation (presumably nannies could take over once the child was ‘born’). Even conservatives who regarded such technologies with distaste felt compelled to agree that they offered the best prospect for maintaining the vitality of the species.

This approach was called ‘positive eugenics’: redressing the imbalance by propagating good genes. It is one that Flight apparently endorses, in his concern that we should not discourage the middle classes from breeding by taking away their cash perks. But the other option, also advocated by Galton, was negative eugenics: preventing breeding among the undesirables. In the many US states that introduced forced-sterilization programmes in the early twentieth century (and which ultimately sterilized around 60,000 people), this meant the mentally unstable or impaired (‘idiots and imbeciles’), as well as perhaps the ‘habitually’ unemployed, criminals and drunkards. In Nazi Germany it came also to mean those whose ‘inferiority’ was a matter of race. (There was no lack of racism in the US programmes either.)

Liberal eugenicists such as Haldane and Huxley were rather more nuanced than Flight. They argued that eugenic policies made sense only on a level playing field: while social inequalities held individuals back, there was no guarantee that ‘defective’ genes would be targeted. But once that levelling was effected, what Huxley referred to chillingly as ‘nests of defective germ plasm’ should be shown no mercy. As he put it, “The lowest strata, allegedly less well endowed genetically, are reproducing relatively too fast. Therefore birth-control methods must be taught them; they must not have too easy access to relief or hospital treatment lest the removal of the last check on natural selection should make it too easy for children to be reproduced or to survive; long unemployment should be a ground for sterilization, or at least relief should be contingent upon no further children being brought into the world.” Flight was at least socially aware enough to pull his punches in comparison to this.

Although it was mostly the taint of Nazism that put paid to eugenics (not to mention the emergence of the concept of human rights), the scientific case was eventually revealed to be spurious too, not least because there is no good reason to think that complex traits such as intelligence and sociability have isolable genetic origins that can be refined by selective breeding.

Yet the survival nonetheless of Galton’s ideas among the likes of Flight and, in previous decades, Sir Keith Joseph, should not be mistaken for a failure to keep abreast of the science. I should be surprised if Flight has even heard of Galton, and I suspect he would be surprised himself to find his remark associated with a word – eugenics – that now is (wrongly) often considered to be a product of fascist genocidal fantasies. Galton was after all only providing pseudo-scientific justification for the prejudices about breeding that the aristocracy had espoused since Plato’s time, and it is surely here that the origins of Flights remark lie. That is why what was evidently for him a casual truism represents more than just a lapse of decorum, sensitivity or political acumen. It implies that David Cameron does not merely have the poor judgement to favour loose cannons, but that he is still heir to a deep-rooted tradition of class-based bigotry.

Friday, November 26, 2010

Funny things that happened on my way to the Forum

This Sunday I appear on the BBC World Service’s ‘ideas’ programme The Forum. In principle I am there to discuss The Music Instinct, but it’s actually a round table discussion about the issues raised by all the guests; my fellows on this occasion are the bio-nanotechnologist Sam Stupp and the polemicist and writer P. J. O’Rourke, whose new book is the characteristically titled Don’t Vote: It Only Encourages the Bastards. I have followed Sam’s work for nigh on two decades: he designs peptides that self-assemble into nanostructures which can act as biodegradable scaffolds for tissue regeneration. It is very neat, and I relished the opportunity to see Sam again. O’Rourke embodies the gentlemanly, amusing Republican whose spine-chilling views on such things as gun laws and the Tea Party are moderated by such charm and worldliness (he is no friend of US xenophobes) that you feel churlish to take issue. I was simply happy to establish that his opposition to Big Government applies only to nations and not to his own home. He is also rather funny, as right-leaning polemicists often are when they are not swivel-eyed. In any event, the programme deserves to be better known – rarely does one get the chance to discuss ideas at such leisure in the broadcast media, even on the beloved BBC.

PS: I just got an update with a direct link to the site for this programme. It includes mugshots, but I can't help that now. Gone are the days when it didn't matter how you looked on the radio.

Monday, November 15, 2010

Beyond the edge of the table

Here’s my Crucible column for the November Chemistry World. It gets a bit heavy-duty towards the end – not often now (happily) that I have to go and read (and pretend to understand) textbooks about quantum electrodynamics. But by happy coincidence, I was introduced recently to the numerology (and Pauli’s enthusiasm for it) by a talk at the Royal Institution by Arthur I. Miller, which I had the pleasure of chairing.

Does the Periodic Table run out? Folk legend asserts that Richard Feynman closed the curtains on the elements after the hypothetical element 137, inelegantly named untrispetium, or more appealingly dubbed feynmanium in his honour.

As physicists (and numerologists) will know, that is no arbitrary cutoff. 137 is an auspicious number – so much so that Feynman himself is said to have recommended that physicists display it prominently in their offices as a reminder of how much they don’t know. Wolfgang Pauli, whose exclusion principle explained the structure of the Periodic Table, was obsessed with the number 137, and discussed its significance over fine wine with his friend and former psychoanalyst Carl Jung – a remarkable relationship explored in Arthur I. Miller’s recent book Deciphering the Cosmic Number (W. W. Norton, 2009). When Pauli was taken ill in Zürich with pancreatic cancer in 1958 and was put in hospital room number 137, he was convinced his time had come – and he was right. For Carl Jung 137 was significant as the number associated with the Jewish mystical tradition called the Cabbalah, as pointed out to physicist Victor Weisskopf by the eminent Jewish scholar Gershom Scholem.

Numerology was not confined to mystics, however, for the ‘explanation’ of the cosmic significance of 137 offered by the astronomer Arthur Eddington was not much more than that. Yet Eddington, Pauli and Feynman were captivated by 137 for the same reason that prompted Feynman to suggest it was where the elements end. For the inverse, 1/137, is almost precisely the value of the so-called fine-structure constant (α), the dimensionless quantity that defines the strength of the electromagnetic interaction – it is in effect the ratio of the square of the electron’s charge to the product of the speed of light and the reduced Planck’s constant.

Why 137? ‘Nobody knows’, Feynman admitted, adding that ‘it’s one of the greatest damn mysteries of physics: a magic number that comes to us with no understanding by man. You might say the hand of God wrote that number, and we don’t know how He pushed his pencil.’ It’s one of the constants that must be added to fundamental physics by hand. Werner Heisenberg was convinced that the problems then plaguing quantum theory would not go away until 137 was ‘explained’. But neither he nor Pauli nor anyone else has cracked the problem. The fact that the denominator of the fine structure constant is not exactly 137, but around 137.035, doesn’t diminish the puzzle, and now this constant is at the centre of arguments about ‘fine-tuning’ of the universe: if it was just 4 percent different, atoms (and we) could not exist.

But was Feynman right about untriseptium? His argument hinged on the fact that α features in the solution of the Dirac equation for the ground-state energy of an atom’s 1s electrons. In effect, when the atomic number Z is equal to or greater than 1/α, the energy becomes imaginary, or in other words, oscillatory – there is no longer a bound state. This doesn’t in itself actually mean that there can be no atoms with Z>137, but rather, there can be no neutral atoms.

However, Feynman’s argument was predicated on a Bohr-type atom in which the nucleus is a point charge. A more accurate prediction of the limiting Z has to take the nucleus’s finite size into account, and the full calculation changes the picture. Now the energy of the 1s orbital doesn’t fall to zero until around Z=150; but actually that is in itself relatively trivial. Even though the bound-state energy becomes negative at larger Z, the 1s electrons remain localized around the nucleus.

But when Z reaches around 173, things get complicated [1]. The bound-state energy then ‘dives’ into what is called the negative continuum: a vacuum ‘sea’ of negative-energy electrons predicted by the Dirac equation. Then the 1s states mix with those in the continuum to create a bound ‘resonance’ state – but the atom remains stable. If the atom’s 1s shell is already ionized, however, containing a single hole, then the consequences are more bizarre: the intense electric field of the nucleus is predicted to pull an electron spontaneously out of the negative continuum to fill it [2]. In other words, an electron-positron pair is created de novo, and the electron plugs the gap in the 1s shell while the positron is emitted.

This behaviour was predicted in the 1970s by Burkhard Fricke of the University of Kassel, working with nuclear physicist Walter Greiner and others [1]. Experiments were conducted during that and the following decade using ‘pseudo-atoms’ – diatomic molecules of two heavy nuclei created in ion collisions – to see if analogous positron emission could be observed from the innermost molecular rather than atomic orbitals. It never was, however, and exactly what would happen for Z>173 remains unresolved.

All the same, it seems that Feynman’s argument does not after all prohibit elements above 137, or even above 173. ‘The Periodic System will not end at 137; in fact it will never end!’, says Greiner triumphantly. Whatever mysteries are posed by the spooky 137, this is apparently not one of them.

1. B. Fricke, W. Greiner & J. T. Waber, Theor. Chim. Acta 21, 235-260 (1971).
2. W. Greiner & J. Reinhardt, Quantum Electrodynamics 4th edn (Springer, Berlin, 2009).

Some like it hot

I have been slack with my postings over the past couple of weeks, so here comes the catching up. First, a Muse for Nature News on a curious paper in PNAS on the origin of life, which seemed to have a corollary not explored by the authors… (I can’t link to the PNAS paper, as it’s not yet been put online, and in the meantime languishes in that peculiar limbo that PNAS commands.)

Heat may have been necessary to ensure that the first prebiotic reactions didn’t take an eternity. If so, this could add weight to the suggestion that water is essential for life in the cosmos.

Should we be surprised to be here? Some scientists maintain that the origin of life is absurdly improbable – Nobel laureate biologist George Wald baldly stated in 1954 that ‘one has only to contemplate the magnitude of [the] task to concede that the spontaneous generation of a living organism is impossible’ [1]. Yet others look at the size of the cosmos and conclude that even such extremely low-probability events are inevitable.

The apparent fine-tuning of physical laws and fundamental constants to enable life’s existence certainly presents a profound puzzle, which the anthropic principle answers only through the profligate hypothesis of multiple universes of which we have the fortune to occupy one that is habitable. But even if we take the laws of nature as we find them, it is hard to know whether or not we should feel fortunate to exist.

One might reasonably argue that the question has little meaning while we still have only a few hundred worlds to compare, about most of which we know next to nothing (not even whether there is, or was, life on our nearest neighbour). But one piece of empirical evidence we do have seems to challenge the notion that the origin of terrestrial life was a piece of extraordinarily good fortune: the geological record implies that life began in a blink, almost the instant the oceans were formed. It is as if it was just waiting to happen – as indeed some have suggested [2]. While Darwinian evolution needed billions of years to find a route from microbe to man, it seems that going from mineral to microbe needs barely a moment.

According to a paper in the Proceedings of the National Academy of Sciences USA by Richard Wolfenden and colleagues at the University of North Carolina, that may be largely a question of chemical kinetics [3]. Just about all the key biochemical processes in living organisms are speeded up by enzyme catalysis; otherwise they would happen too slowly or indiscriminately to make metabolism and life feasible. Some key processes, such as reactions involved in biosynthesis of nucleic acids, happen at a glacial pace without enzymes. If so, how did the earliest living systems bootstrap themselves to the point where they could sustain and reproduce themselves with enzymatic assistance?

The researchers think that temperature was the key. They point out that, not only do reactions speed up with temperature more than is commonly appreciated, but that the slowest reactions speed up the most: a change from 25 C to 100 C, for example, increases the rate of some prebiotically relevant reactions by 10 million-fold.

There’s reason to believe that life may have started in hot water, for example around submarine volcanic vents, where there are abundant supplies of energy, inorganic nutrients and simple molecular building blocks. Some of the earliest branches in the phylogenetic tree of life are occupied by thermophilic organisms, which thrive in hot conditions. A hot, aqueous origin of life is probably now the leading candidate for this mysterious event.

This alone, then, could reduce the timescales needed for a primitive biochemistry to get going from millions to tens of years. What’s more, say Wolfenden and colleagues, some of the best non-enzyme catalysts of slow metabolic reactions, which might have served as prebiotic proto-enzymes, becomes more effective as the temperature is lowered. If that’s what happened on the early Earth, then once catalysis took over from simple temperature-induced acceleration, it would have not suffered as the environment cooled or as life spread to cooler regions.

If this scenario is right, it could constrain on the kinds of worlds that support life. We know that watery worlds can do this; but might other simple liquids act as solvents for different biochemistries? In general, these have lower freezing points than water, such as the liquid hydrocarbons of Saturn’s moon Titan, ammonia (on Jupiter, say), formamide (HCONH2) or water-ammonia mixtures. One can enumerate reasons why in some respects these ‘cold’ liquids might be better solvents for life than water [4]. But if the rates of prebiotic reactions were a limiting factor in life’s origin, it may be that colder seas would never move things along fast enough.

Hotter may not be better either: quite aside from the difficulty of imagining plausible biochemistries in molten silicates, complex molecules would tend more readily to fall apart in extreme heat both because bonds snap more easily and because entropy favours disintegration over union. All of which could lend credence to the suggestion of biochemist Lawrence Henderson in 1913 that water is peculiarly biophilic [5]. In the introduction to a 1958 edition of Henderson’s book, Wald wrote ‘we now believe that life… must arise inevitably wherever it can, given enough time.’ But perhaps what it needs is not so much enough time, but enough heat.

1. G. Wald, Sci. Am. 191, 44-53 (1954).
2. H. J. Morowitz & E. Smith, Complexity 13, 51-59 (2007).
3. R. B. Stockbridge, C. A. Lewis Jr, Y. Yuan & R. Woldenden, Proc. Natl Acad. Sci. USA doi:10.1073/pnas.1013647107.
4. S. A. Benner, in Water and Life (eds R. M. Lynden-Bell, S. Conway Morris, J. D. Barrow, J. L. Finney & C. L. Harper, Jr, Chapter 10. CRC Press, Boca Raton, 2010.
5. L. J. Henderson, The Fitness of the Environment. Macmillan, New York, 1913.