Against big ideas

Sam Leith’s comment on the trend in non-fiction publishing is spot-on, and Toby Mundy’s analysis of it typically insightful. (And I’m not saying that just because you’re the new director of the Samuel Johnson prize, Toby – though, you know, congratulations and all.) Sam echoes my impression, though I suppose as someone published in the UK by Bodley Head (rightly exonerated here as a noble exception) and in the US by the University of Chicago Press, I would say this. It is good to have critical reviewers around, like Steven Poole and Bryan Appleyard, who will challenge this Gladwellization of non-fiction, but I fear they’re fighting against the tide. Sam’s complaint about the way the mainstream trade publishers seem mostly interested in books that offer a single “big idea” that explains everything about being human/history/the brain/the economy/the internet/the universe (until the next one comes along) is very well founded. Life is not just complex (in which case “complexity theory” would explain it all right?) but complicated. So are most areas of science. So are people. We need ideas and narratives that help us unravel the threads, not ones that pretend it is all just one big rope. This seems especially problematic in the US, where it feels ever harder – outside of the university presses – to publish a serious discussion of any topic rather than an airport book in which the subtitle tells you all you need to know. It’s very reassuring to hear that being published there by a university press there is increasingly a guarantor of substance.

The many truths of Tim Hunt

Blimey. That Tim Hunt then. It feels like any single point of view is not enough; I need a superposition of states here. I read Athene Donald explaining that, however much we can and should deplore his comments, he’s not a bad chap, and I think yes, that was very much my experience of Tim when I was on a judging panel with him: I liked him, found him not at all bigoted or oppressive or objectionable. Comparisons with Jim Watson are unfair – I think it is clear he is not that kind of person. Athene seems right to be saying, let’s not make it all about Tim, we need to focus on measures that will rid science of the blight of sexism that still evidently afflicts it.

Then I read responses and comments by Jenny Rohn, Margaret Harris and Deborah Blum, and I think yes, we mustn’t offer up feeble “he’s just a different generation” excuses and give a basically decent chap a break for making a stupid blunder. There is too much of this sort of low-level crap going on in science all the time, and when it comes from someone in a position of such authority and influence then we need to come down hard on it.

I can’t help feeling a bit sorry for Tim, seeing how genuinely distraught and despairing he seems. Christ, the man is human, and not a monster. And yet I can’t help feeling, you bloody fool, what really did you expect? And I don’t know quite what to believe anyway. Do we accept this as a bone-headed attempt at a joke, or do we believe that Tim passed up the chance to say later that of course he didn’t truly think these things? Do we believe rumours that Tim had form for this kind of thing, or accept the testimony of friends and colleagues that they’ve never seen him previously behave in a sexist manner?

The world can’t possibly need someone else saying “Here’s what we should do about Huntgate.” (I’m glad that’s not a word. Forget I wrote it.) But. Well, I’d simply like to offer a fee suggestions:
1. We stop name-calling and belitting of anyone who, while condemning the remarks, differs slightly from our own view of what is the appropriate way to deal with them. There’s no obvious right answer to that. What’s needed is discussion. (Obviously, this excludes London mayors who think Tim was merely pointing out some well known gender differences, and who in any event reckon it is OK to make off-the-cuff jokes about “piccaninnies”.)

2. We agree that denouncements of “politically correct witch hunts” are beside the point. People on Twitter will say horrid and unfair things about Tim Hunt because people on Twitter do that. Why cares (aside from the fact that it’s intrinsically nasty)? I see no reason to call the responses of, say, UCL, a witch hunt, let alone a “politically correct” one (unless your view is that it is trendy political correctness to show disapproval of sexism and want to distance yourself from it).

3. Tim’s situation has been worsened by the timing. People are frankly and rightly sick of the sexism that exists in science. When I think that my girls, were they to choose careers in science, might have their prospects damaged by bias, harassment, and exclusion, I want to take a hammer and smash up a lot of Pyrex. Actually I think I will encourage them to do it themselves (I suspect they’ll be quite good at it). I’m not saying that Tim got worse than he deserved for this reason, but just that it’s a part of the explanation for what happened.

4. We follow Athene’s action points, and use this sad affair positively to make change happen.

5. We stop making excuses. We can all make mistakes and say thoughtless things, for sure, but having an attitude that fundamentally opposes discrimination of all sorts and recognizes it when we see it in so obvious a manner as this is not bloody hard, whether you are 17 or 70. Science is, frankly, a bit crap at this. It tolerates obnoxious fools for too long, on the grounds that they once did some good science. (I’m not talking about Tim here.) It doesn’t just tolerate them, it excuses them. I don’t give a toss how good your science is, if you don’t behave decently and respectfully then you should expect to get no respect in return.

But here’s what gives me great hope and comfort: I’m not sure science is going to be this way much longer. It’s going to take time and effort, but it will change. I am buoyed by the fact that the ambassadors for science these days (and here I’m qualified only to talk about the UK) are people for who “jokes” about women scientists (no, “girls”) falling in love and crying and working in segregated labs aren’t just objectionable but utterly bloody weird. People to whom it would never occur to say or think such an outlandish thing no matter how “confused” or “nervous” or jet-lagged or drunk they were. People like Athene Donald, like Monica Grady, Alice Roberts, Maggie Aderin-Pocock, Brian Cox, Jim Al-Khalili, Mark Miodownik, Ed Yong, Andrea Sella. Certain older members of the science-communication fraternity (I use the word advisedly, and mention no names) might just purse their lips and mutter about witch hunts and the waste of scientific eminence. But their time is over.

Christiaan Huygens - the first astrobiologist?

Necessarily cut from my piece in Nautilus on water and astrobiology was a paragraph of very early history, in which Christiaan Huygens anticipates this whole debate with eerie prescience. I hope it’s worth filling in that bit of the story here.

Galileo had looked at the moon and saw not the smooth, featureless sphere that Aristotelians believed in but mountains and valleys, their rugged topography picked out by the raking light of the Sun at the boundary where light meets darkness. Within just a couple of decades, writers and philosophers were starting to imagine journeying to this new world, much as Columbus had travelled to the Americas. The natural philosopher John Wilkins gave a factual account in his Discovery of a World in the Moone (1638), while the French soldier and writer Cyrano de Bergerac penned a satirical account of spaceflight in The States and Empires of the Moon, published posthumously in 1657. By the end of the century, scientists were starting to speculate about what the environments of these other worlds might be like.

In his posthumously published 1698 book Cosmotheoros, Huygens asserted that plants and animals on other planets must derive their “growth and nourishment” from “some liquid principle”. But he realized that water would freeze on Jupiter or Saturn, and so “Every planet therefore must have its waters of such a temper, as to be proportion’d to its heat”: Jupiter’s and Saturn’s “waters” must have a lower freezing point, and those of Venus and Mercury a higher boiling point. In other words, it isn’t too fanciful to say that Huygens was speculating that life on other planets might use non-aqueous solvents.

In my Nautilus article I veer towards the notion that there might be non-aqueous solvents for life. In my more technical article for the book Astrochemistry and Astrobiology (eds I. W. M. Smith, C. S. Cockell & S. Leach; Springer, Heidelberg, 2013), I equivocate rather more. It seems to me that this kind of Socratic dialogue (to be absurdly grandiose about it) is the best way of approaching the problem: one can make both cases, and it is hard to adduce any clear evidence at this point for which of them we should prefer. This is what I say in that latter piece:

“Attempts to enunciate the irreducible molecular-scale requirements for (as opposed to the emergent characteristics of) something we might recognize as life have been rather sporadic, and are often hampered by the difficulty of looking at the question through anything other than aqua-tinted spectacles. From the point of view of thinking about non-aqueous astrobiological solvents, a review of water’s roles in terrestrial biochemistry surely raises one key consideration straight away: it is not sufficient, in this context, to imagine a clear separation between the ‘molecular machinery’ and the solvent. There is a two-way exchange of behaviours between them, and this literally erases any dividing line between the biological components and their environment.

The key questions here are, then, necessarily vague. But the more we understand about the biochemical aspects of water, the less likely it seems that another solvent could mimic its versatility, sensitivity and responsiveness, for example to distinguish any old collapsed polypeptide chain from a fully functioning protein. It is perhaps this notion of responsiveness that emerges as the chief characteristic from a survey of water’s biological roles. It can be manipulated in three dimensions to augment the influence of biomolecules. It can receive and transmit their dynamical behaviours, and at the same time it can impose its own influence on solute dynamics so that some biomolecular behaviours become a kind of intimate conspiracy between solute and solvent. This adaptive sensitivity seems to facilitate the kind of compromise between structural integrity and reconfigurability that lies at the heart of many biomolecular processes, including molecular recognition, catalytic activity, conformational flexibility, long-range informational transfer and the ability to adapt to new environments. It is easy to imagine – but very hard to prove! – that such properties are likely to be needed in any molecular system with sufficient complexity to grow, replicate, metabolize and evolve – in other words, to qualify as living.

In these respects it does seem challenging to postulate any solvent that can hold a candle to water – not so much in terms of what it does, but in terms of the opportunities it offers for molecular evolution. This is by no means to endorse the dictum of NASA that astrobiologists need to ‘follow the water’. But hopefully it might sharpen the question of where else we might look.”

Set for chemistry: a longer view

It seems quite a lot of folk liked to hear about the old chemistry sets that I discussed in my article in Chemistry World. It was certainly a blast writing it. I didn’t mention, because she asked me not to quote yet, that Rebecca Onion has also been looking into this topic – I hope it’s OK to say now that she'll shortly be publishing something rather wonderful on it. In any event, I thought it would be worth putting up the full original article here. The images are, except where indicated, all courtesy of the Chemical Heritage Foundation, and I reckon that their exhibition in the autumn is going to be fabulous.

______________________________________________________________________

As you’re reading Chemistry World, I bet you had a chemistry set. Maybe you tinkered with a substantial rack of test-tubes containing compounds that would now be considered daring: potassium permanganate, sodium thiocyanate, perhaps supplemented with stronger stuff bought at the chemical supplier’s or “borrowed” from school: nitric acid, lumps of sodium under oil. Younger readers might have been denied such pleasures, having to be content with litmus paper for measuring soil pH. Today’s sets are likely to be more about “kitchen chemistry” or “colour chemistry”, using nothing more hazardous than bicarb and food dyes.

The content, appearance and aspirations of your chemistry set age you as much as your choice in music. When I recently got to look at the marvelous collection in the vaults of the Chemical Heritage Foundation in Philadelphia, I was struck by how these alluring boxes encode social narratives. They reflect changing perceptions of chemistry and science as a whole, shifts in the social strata of the target consumers, in attitudes to gender and in the objectives of science education. “Chemistry sets and science kits contained much more than vials of chemicals, test tubes, and microscopes”, says art historian and independent curator Jane E. Boyd, who is curating an exhibition of the CHF’s sets that opens in October. “Their colourful boxes and cases also held manufacturers’ ambitions for success and prestige, parents’ hopes and anxieties for the future lives of their sons and daughters, and children’s own desires for fun and excitement.”

What were these sets for? Are they toys? Were the meant to educate or to amuse? Why were they produced, and for who? And why do they seem – I’m sure it isn’t just me – to pack such a nostalgic punch?

The magic of chemistry

Chemical sets aimed at children started to appear from around the 1830s. One of the earliest was the “No. 1. Youth’s Laboratory, or Chemical Amusement Box”, produced in 1836-7 by the chemist Robert Best Ede. It contained “more than 40 Chemical preparations and appropriate apparatus, for enabling the enquiring youth… to perform above 100 Amusing and Interesting Experiments with perfect ease and free from danger.” These cabinets were luxury items: Ede’s was mahogany-cased and sold for the tidy sum of 16 shillings. Historian Melanie Keene of Cambridge University has shown, while the contents of the nineteenth-century cabinets were quite ambitious in their chemical scope, containing such compounds as potassium “superoxalate”, “prussiate” and “bi-chromate”, the emphasis of the booklets was on making chemistry “familiar”, with reference to household items such as soap or candles [1].


Robert Best Ede’s “Portable Laboratory”, c.1836. Wellcome Library, London.

It wasn’t until the second half of the nineteenth century that toy manufacturers began to make commercial sets as educational tools tailored for the affluent middle classes. The intended audience is clear from one of the CHF’s earliest items, a Chemcraft set sold around 1917 by the Porter Chemical Company in Hagerstown, Maryland, one of the major manufacturers of chemistry sets in the USA throughout most of the twentieth century. Like Ede’s set almost a century earlier, it is housed in a handsome wooden box with the ingredients kept in elegant little wooden bottles. The lid shows a well-bred young lad in suit and tie, hair neatly gelled, bending over his little burner under the watchful eye of his father.



Alongside but independent of the chemical cabinets, science popularizers of the nineteenth century produced how-to manuals describing experiments for children using household ingredients. Ede’s earliest cabinets were intended to accompany the popular 1823 book on chemical experimentation, Chemical Recreations by John Joseph Griffin – but Ede’s company later sold them independently with its own bespoke pamphlet. These two traditions of the cabinet and the booklet merged, so that when the cabinets became available to a wider “toy” market at a slightly cheaper price from the 1900s, the accompanying instruction manual became indispensible.

Both the early chemistry sets and the experimental booklets had a strong link to the tradition of “performative chemistry” that developed during the nineteenth century. Dramatic chemical demonstrations were a hallmark of the public talks at the Royal Institution given by Humphry Davy and Michael Faraday in the early part of the century. “These performances were intended to make chemistry ‘familiar’, as enticements to active practical investigations that could be carried out in the home”, says historian of science Salim Al-Gailani of the University of Cambridge, who has made one of the few detailed studies of chemistry sets [2]. He says there is a clear link between publications such as Faraday's book of his RI lectures, Chemical History of a Candle (1861), the penny-pamphlet handbooks, and later chemistry-set manuals.

Chemistry displays, lodged somewhere between music-hall spectacle and public education, were refined at institutions such as the Royal Polytechnic Institute in London, where lecturers like John Henry Pepper wowed audiences with chemical magic. Pepper, best known for devising the illusion of “Pepper’s ghost” used in performances of Hamlet and A Christmas Carol, went on to set up his own Theatre of Popular Science and Entertainment at the Egyptian Hall in London, the home of Victorian stage magic, and took his show on tour in the USA and Australia. Some stage magicians were even contracted to write popular treatises on chemistry.


A chemical manual from c.1894, in which the link to stage magic is clear. (Harry Price Library, UCL)

This link between stage magic and the early chemistry sets is personified in Albert Gilbert, the founder of the A. C. Gilbert Company of New Haven, Connecticut, which was the main US rival to Porter’s Chemcraft and became one of the biggest toy firms in the world. Gilbert was a stage magician, and he founded his company in 1909 to supply materials for magic shows, marketed under the brand Mysto Magic.

The early Chemcraft sets reflect this association too, promising “Mysterious experiments in chemical magic.” There were hints of a connection with alchemy, for example in the suggestion that the deposition of copper onto iron was a kind of transmutation. The manuals offered tips on how to stage a magical demonstration, combining practical instruction with the misdirection and sleight-of-hand methods of the magician. This dabbling with the old imagery of alchemy was sometimes filtered through racial stereotyping that seems shocking now. One Chemcraft manual suggested that the performer dress as some sort of Oriental fellow, like a “Hindu prince or Rajah.” And he would need an assistant “made up as an Ethiopian slave”, with “his face and arms blackened with burned cork”. He should be given “a fantastic name such as Allah, Kola, Rota or any foreign-sounding word.”

“The influence of ‘natural magic’ continued to shape the iconography and pedagogical function of chemistry sets well into the twentieth century”, says Al-Gailani. Even one of the CHF’s most recent sets, from around 1994, was marketed under the “Mr Wizard” brand, harking back to the American television show Watch Mr Wizard produced and presented by Don Herbert from 1951 to 1965. Herbert aimed to demonstrate the science behind the everyday, and he revived the show (and the brand) from 1983 to 1990 as Mr Wizard’s World for the children’s channel Nickelodeon.


Still revealing the magical secrets of nature in the 1990s?

While children might delight in the prospect of mysterious thrills, the parents who forked out for these sets were more likely to be persuaded by the idea that they would be educational and improving. Chemistry experimentation was often presented in the late nineteenth century as morally virtuous: as Griffin put it, “Chemistry is a subject qualified to train both the mind and the hands of young people to habits of industry, regularity, and order”. Such manuals stressed cleanliness, dexterity and common sense – a stark contrast to the “diabolical sorcery” that one might find promised in magic-themed chemistry. The early twentieth-century makers of chemistry sets sometimes tried to reconcile the contradictions by suggesting that they were demystifying the stunts still then being pulled off by mediums and spiritualists. As one Gilbert manual put it in 1920, “We explain how they are performed by purely natural means.”

This tension, says Boyd, is just one of the “many contradictions inside these eye-catching boxes: between dreams and reality, structured learning and free exploration, mysterious magic and rational science, safety and danger.” The boxes in which the kits were housed sent out contrasting messages about what home chemistry was all about. Many show the experimenter as a young scientist, in the time-honoured chemist’s pose of holding up a test-tube or flask of coloured liquid. Some offer a futuristic, utopian vision of science as saviour, perhaps with the tubes of a chemicals plant hovering in the background. “Experimenter today, scientist tomorrow”, promises a Chemcraft manual from 1934.


A brave new world promised by Chemcraft.


“Experimenter today, scientist tomorrow”

Toys for the boys

The imagery throughout is decidedly male. “Manufacturers’ expectations and assumptions about masculinity are particularly apparent in chemistry set marketing copy in the United States in the twentieth century”, says Al-Gailani. He points out that, after the Second World War, chemical experiments that might earlier have been presented as “magic”, such as invisible ink, would instead be likened to the crime-sleuthing associated with the FBI, “an institution that was immensely influential in defining and popularising the predominant ‘all-American, square-jawed’ masculinity of the post-war era”. Chemistry was not just a male but a manly affair. The disheveled “mad scientist”, while beginning to feature in movies, is nowhere to be found here – instead, the young experimenter is smartly dressed and well disciplined, accustomed to following instruction (manuals). If he obeyed the rules, a chemistry set wasn’t just a recreational pursuit but a preparation for a career in science.

Did girls get a look in? A British Lott’s set from around 1915 claims that it is for both boys and girls, and reassuringly places the home chemistry lab in what looks rather like a domestic kitchen, albeit with (highly questionable) periodic tables on the walls. But if girls did chemistry, it was with a view to preparing them for their obligations in “mother’s kitchen”, not the laboratory. As a Chemcraft manual put it in 1933 “in the home, the housewife who knows nothing of the chemistry of the foods she prepares or the materials which she uses daily is handicapped”. The man who knows no chemistry is handicapped too, the manual adds – but strictly in the professional, not domestic, domain. It was the father’s duty to inculcate such knowledge in his son in preparation for a life of work, just as the mother should educate her daughter in the chemistry of cooking and domestic chores.


A Lott’s chemistry set made in England, c.1915


For boy’s only?

When Gilbert finally produced a set specifically for girls in the late 1950s, fetchingly decorated in pastel pink, it is not exactly a “chemist’s set” at all. Instead it reminds the girl who squints into a microscope, while her big sister looks on encouragingly, that all she can aspire to is to use her natural domestic skills to become a “lab technician”.


…or for girls too (if they don’t aspire too high)?

Keeping safe

By the 1970s things seem to have improved a little. Both girls and boys, as golden-haired and wide-collared as David Soul, feature on the lid of Johnny Horizon’s chemical set, although the girl seems to be reduced to looking on adoringly as her brother (boyfriend?) does the measuring and pouring. Yet this is no longer marketed as a chemistry set: in the post-Silent Spring era it is now an “Environmental Testing Kit”. “Is the air around you polluted?” it asks. You can examine river waters for contamination too, and the set promises that you and your family “will be able to do more about our environmental problems.”


A chemistry set post-Silent Spring.

How times change. What would those who bought the Johnny Horizon kit have made of Chemcraft’s offering from the late 1940s, which includes “safe experiments in atomic energy”, including – probably my favourite element (literally) of the entire CHF collection – uranium ore and a “radio active screen”? The latter is incorporated into a “spinthariscope”, a device first invented by the chemist and entrepreneur William Crookes in 1903, which uses a zinc sulfide phosphor screen to reveal the scintillations of alpha particles.


Home experiments in atomic energy, c. 1948.

Compare this with the Tree of Knowledge Chem-Science set from around 2000-2005, which – despite offering standard experiments such as the bicarb-vinegar volcano and litmus testing – assures the buyer that the “35 fun activities” contain “no chemicals”.


The Tree of Knowledge Chem-Science set (c.2000-2005) takes no risks.

If you’re inclined to bewail this apparent taming of home chemistry for kids, bear in mind that social anxieties about safety are nothing new. A concerned parent wrote to the Times in 1903 warning that “the placing in the hands of young boys of such ingredients as chlorate of potash, sulphur, &c., must always be deprecated as a temptingly dangerous proceeding”. (If only we could have responded by saying “Yes, that’s the point.”)

“The idea that the sets used to have terribly dangerous materials in them, and then these gradually got nanny-stated out, isn’t fully supported by the sets themselves”, cautions CHF curatorial assistant Elisabeth Berry Drago. “Even the earliest sets contained fairly innocuous stuff: things that were corrosive, or shouldn’t be inhaled, but not intrinsically deadly or dangerous.”

Compare, for example, the contents of the Lott’s chemistry set from around 1915 with those of a 1965 Skil Craft set (see Box): there was rather little change over five decades. “The ads and print material demonstrate that a concern for safety and toxicity was not a late development, but something that was very much a part of the context from early on”, says Drago. “Even in 1917 the onus is on safety.” The Porter Chemcraft set from that era insists that it is “Perfectly safe” and “Contains no poisonous or otherwise harmful substances”. Yet there was probably more concern about the sources of heating than about the chemical ingredients. Early chemistry sets contained Bunsen burners, Drago says, while later even “alcohol lamps with open flames are not considered child-safe any more.”

This wasn’t simply a matter of changing perceptions of what was hazardous, but also of who was to blame: as medical historian John Burnham of Ohio State university has argued3, there was an increasing tendency over the course of the twentieth century to switch the responsibility for child safety from parents (particularly mothers) to manufacturers and the “engineering” of the childhood environment. If manufacturers were to be held responsible for accidents, they weren’t going to take any risks.

“There is no doubt that contents of today's chemistry sets are far tamer than they were a few generations ago”, says Al-Gailani. But he is not convinced that this is the only or even main reason behind the much lamented “decline in popularity of the chemistry set.” To understand that, he says, “we need a much better understanding of wider shifts in the toy industry, especially the perceived profitability of scientific toys, and the place of chemistry in popular culture.” He thinks that the perception that the chemistry set should play a role in drawing children into science “has a lot to do with the iconic status of the chemistry set in writing about scientific careers and nostalgia for a less risk-averse era” – that it’s a story we tell, but not necessarily the right or complete one.

Smells and stinks

The chemistry set today is rarely marketed with the sobriety of the past. It emphasizes science as fun – smelly, disgusting, tactile and visual. We will surely one day be judged for this, for better or worse. There are certainly dangers in suggesting that chemistry is going to be relentlessly fun and entertaining, selling itself on stinks and bangs, as UCL chemist Andrea Sella argued when accepting the Royal Society Faraday Prize for communicating science this year.

But those sensual delights are harder to procure anyway when the range of chemicals permitted in a chemistry set is constrained. One alternative – some will see as a poor one, lacking the true tactile and aromatic sensations of chemistry – is the CHF’s Chemcrafter app, tellingly displayed in a 1950s visual style.


The chemistry set of the future? The Chemcrafter app from the Chemical Heritage Foundation.

Yet the questions confronting manufacturers now are in some ways not so different than ever they were. Should chemistry be made to feel exotic or familiar? Are chemistry sets about fun or sober instruction, and how far can the two be combined? Should they be marketed at the children (and which children?), or their parents? Whatever answers we find will say a lot about us.


Totally gross: chemistry sets today.

__________________________________________________________________________

Box: What’s in the Box?

In circa 1915, the British Lott’s Bricks Chemistry Set No. 5 contained the following:
“Alum powder, ammonium carbonate, ammonium chloride, borax, calcium carbonate, charcoal (powdered), Congo red, copper sulfate, iron filings, iron sulfate, lime, manganese dioxide, potassium bichromate, potassium permanganate, potassium iodate, potassium iodide, potassium nitrate, “Sky blue”, sodium bicarbonate, sodium bisulfate, sodium carbonate, sodium nitrite, sodium thiosulfate, strontium nitrate, sulfur and zinc.”

In 1965 the Skil Craft Chemistry Set contained these ingredients:
“Ammonium chloride, gum arabic, cobalt chloride, sulfur, calcium chloride, sodium silicate solution, phenolphthalein solution, tannic acid, sodium ferrocyanide, manganous sulfate, sodium thiosulfate, ferric ammonium sulfate, sodium salicylate, borax, sodium bisulfate, and aluminum sulfate.”



__________________________________________________________________________

References
1. M. Keene, Ambix 60, 54 (2013).
2. S. Al-Gailani, Stud. Hist. Phil. Sci. 40, 372 (2009).
3. J. C. Burnham, J. Soc. Hist. 29, 817 (1996).

The Chemical Heritage Foundation’s exhibition Science at Play: 100 Years of Chemistry Sets and Science Kits runs from October 2015 to September 2016 in Philadelphia.

BB's blues

My tribute to the late, great B. B. King for my “music cognition” column in the next issue of Sapere.
________________________________________________________________________

B. B. King, who died aged 89 on 14th May, was one of the first guitarists to evolve a style of playing that instantly identified him. His sweet, plaintive sound was so closely associated with the Gibson guitars he used to call Lucille that the Gibson Corporation launched a “Lucille” model in 1980. But it was the way he played them that mattered: bending notes that strayed far from the standard diatonic scale of Western music, especially on the fifth of the scale and the famous “blue” notes of blues and jazz: the third and the flattened seventh, which in the key of C correspond to E and B flat. The “blues third” lies in an ambiguous space between the minor third (E flat in C) and the major third (E natural), so that in the convention that makes major keys “happy” and minor keys “sad”, the blues – and especially B. B.’s blues – take on a bittersweet character, the sound of loves recalled and lost.

All this from simply playing “out of tune”? Well yes, because it’s precisely this quality that animates folk music in many traditions, giving it a soul that dies whenever classically trained musicians attempt to “go popular” and bring their perfect intonation to a musical form that demands rough edges. When musicologists and anthropologists first started to study folk music seriously in the early twentieth century, at first they often took the “imperfect” tunings to reflect poor technique – until they realised that the performers (usually singers) would replicate these off-key notes precisely from one rendition to the next. They knew what they were doing.

And what they were doing was what all music so often does when it pulls the emotions: it introduces uncertainty and ambiguity, creating a tension in the listener that turns into passion.

This is an easy principle to grasp, but fiendishly hard to get right. When other guitarists sought to emulate B. B., or singers to copy Billie Holliday doing the same thing with her vocal blue notes, they risked cliché or straining for effect. It takes exquisite judgement to keep the detuning emotive rather than kitsch. You’ve got to know how far to push it, perhaps quite literally. Will B. B. bend that note from a minor right up to a major third, “resolving” the discord and telling us that the story came good in the end? No, not quite – his hopes, like his intonation, are thwarted: joy withheld at the last moment. The thrill is gone.

The moral challenge of invisibility

Here is an extended version of my latest piece for Nature News. There are of course more details about lots of the things discussed here in my book Invisible.

__________________________________________________________________

Experiments that give subjects the illusion of having an invisible body might reveal how we respond to the ensuing temptations.

We’ve all had those moments of social embarrassment: you’ve just said or done the dumbest thing, everyone is looking at you, and you wish you could just – well, vanish. But what if you really could? Would that help?

Apparently it would. Using a virtual-reality headset and a calculated confusion of the senses, neuroscientists at the Karolinska Institute in Stockholm, Sweden, have been able to give people the illusion that their body is invisible [1]. The subjects feel someone stroking their body with a brush, but when they look down all they see is the brush moving through thin air. This is enough, they testify, to give them the sensation that their entire body cannot be seen. It feels, many say, not only invisible but hollow – a weird dematerialization of their physical person.

And according to both the testaments of the subjects and objective measurement of their physiological response to stress as revealed by their heartbeat rate, this sensation of invisibility reduces their anxiety in social settings, for example if they can see an audience of “serious-looking strangers” seated and watching them.

Why would you want to know what it’s like to have an invisible body? One potential reason is that the technique could be used to treat social anxiety disorder, in which people are acutely susceptible to stress in situations such as having to deliver a presentation or perform before an audience. This is a very common disorder, affecting an estimated one in ten people at some point during their life. They sweat, shake, blush and hear their heart thumping away. Aside from prescribing anti-anxiety medication, this condition is generally treated with cognitive behavioural therapy, which attempts to condition the subjects by degrees to stay calm in a socially stressful setting.

Virtual reality has already shown its value in such treatment. But what if, say the Stockholm team, led by Henrik Ehrsson, you could “give” a patient an invisible body and then gradually make them more visible in stages? The illusion that they create is, after all, a matter of degree: subjects said that they experienced varying depths of visibility, depending on the conditions.

The illusion is also related to studies of how a sense of “body ownership” is triggered by visual and tactile stimuli. In 1998, psychologists Matthew Botvinick and Jonathan Cohen showed that when people see a rubber hand being brushed at the same time as their own hand, out of sight, experiences the same sensation, they feel that the rubber hand is part of their body [2]. Ehrsson and colleagues recently showed that this “rubber hand” illusion can even be invoked for an “invisible hand”, when subjects see the sensation that they feel applied to empty space [3]. That’s what inspired them to carry out the present study, and the results could also cast light on the “phantom body” illusion experienced by some people with paralysis due to spinal-cord injuries, in which they feel they have a body that is out of alignment with their real one.

So, plenty of potential clinical applications. But the research touches on something far deeper, for notions of personal invisibility feature in many of our myths, legends and stories, from Plato’s telling of the myth of Gyges in his Republic to H. G. Wells’ Invisible Man, J. R. R. Tolkien’s The Lord of the Rings and Harry Potter. Invisibility there has other connotations. Gyges is a shepherd of Lydia who discovers a ring of invisibility by chance, and uses it to seduce the queen, kill the king, and make himself ruler. The moral, says Plato’s narrator Glaucon, is that
“No man can be imagined to be of such an iron nature that he would stand fast in justice. No man would keep his hands off what was not his own when he could safely take what he liked out of the market, or go into houses and lie with anyone at his pleasure, or kill or release from prison whom he would, and in all respects be like a God among men.”

Wells seems to have intended his novel to be an updating of the Gyges story, demonstrating the corrupting temptations of invisibility and its severance of personal responsibility. He took great pains to make his invisibility scientifically plausible by the standards of the time, and interestingly he anticipated that an inability to see one’s limbs would confuse the coordination: his invisible man initially can barely walk. Ehrsson’s coauthor Arvid Guterstam says this is something they can now test, but he doesn’t anticipate such an effect. “We are already very used to moving our limbs without directly looking at them, when they are occluded or in the dark”, he says, “so guiding our limbs through space without direct visual feedback shouldn’t be a major issue.” We wouldn’t, it seems, become like David McCallum’s Invisible Man in the 1970s television serial of that name, forever blundering into potted plants – an exigency forced on him, the series producer Robert O’Neill admitted, by the challenge of convincing an audience that an invisible person was actually there.

But would invisibility also confuse our morals? This is where the new work could get really interesting, because the researchers want to examine this “Gyges effect”. “We are planning to expose participants to a number of moral dilemmas under the illusion that they are invisible”, says Guterstam, “and compare their responses to a context in which they perceive having a normal physical body.” I anticipate the worst here, not least because the Gyges effect seems already to operate in internet trolling [4].

One thing is for sure: we should take with a big pinch of salt the authors’ suggestion that there is “the emerging prospect of invisibility cloaking of an entire human body being made possible by modern materials science”. This alludes to recent work on so-called metamaterial invisibility cloaks [5,6]. But not only is that work very far from achieving full cloaking in the visible spectrum (let alone in a wearable suit), but there is good reason to suspect that it will stay that way for the foreseeable future. The hiding of a cat and fish that Ehrsson and colleagues mention [7] sounds impressive but is in the end a kind of high-tech version of the Victorian stage magician’s trick of using mirrors (and probably smoke) to make half a woman’s body vanish.

There are other technologies afoot for making “invisibility cloaks” for humans, generally involving a kind of adaptive camouflage in which the background is either projected onto highly reflective clothing [8] or captured with “onboard” cameras and displayed on wearable LED screens [9]. The first offers a compromised and static illusion – if you want to appear transparent while you give your presentation, you’d do just as well to stand in front of the projector. The second is another speculative and remote (albeit fun) idea that is in any event undermined by the laws of optics [10]. So fear not – no one is going to become a real-life Gyges any time soon.

1. Guterstam, A., Abdulkarim, Z. & Ehrsson, H. H., Sci. Rep. 5, 9831 (2015). (here)
2. Botvinick, M. & Cohen, J., Nature 391, 756 
(1998). (here)
3. Guterstam, A., Gentile, G. & Ehrsson, H. H. J. Cogn. Neurosci. 25, 1078–1099 (2013).
4. Hardaker, C. Guardian 3 August 2013. (here)
5. Schurig, D., Mock, J. J., Justice, B. J., Cummer, S. A., Pendry, J. B., Starr, A. F. & Smith, D. R., Science 314, 977-980 (2006).
6. Leonhardt U.&. Philbin, T. G., Geometry and Light: The Science of Invisibility. Dover, Mineola, 2010.
7. Chen, H. et al., preprint http://www.arxiv.org/abs/1306.1780 (2013).
8. Tachi, S. Proc. 5th Virtual Reality Int. Conf. (VRIC2003), 69/1-69/9 (Laval Virtual, France, 2003). (here)
9. Zambonelli, F. & Mamei, M. Pervasive Computing 1(4), 62-70 (2002) (here).
10. See comments by M. Hebert in ref. 8.

Goebbels: the gift that keeps on giving?

The story about demands (on my publisher) for royalties for quoting Goebbels raises fascinating issues. It is all the more complex because of the fact that the claim on behalf of Goebbels’ estate is being pursued by the daughter of Hjalmar Schacht, Hitler’s Economic Minister, who is a lawyer.

I considered Schacht’s story briefly in my book Serving the Reich; a more detailed account is given in Eric Kurlander’s excellent Living With Hitler. Schacht offers an interesting case study of the complexities of anti-Semitism during the Nazi regime. He was in many respects a liberal, and although he became a supporter of the Nazis and President of the Reichsbank, he lost his influence after a disagreement with Hitler in 1937 (“You simply do not conform to the general National Socialist framework”, Hitler told him two years later) and eventually became a member of the German Resistance. He was imprisoned after the failed assassination plot of June 1944 and sent to Dachau, but survived.

Schacht seems to have been instinctively averse to racial hatred, and was frequently reprimanded by Party officials for speaking out against attacks on Jews and their property. He argued against some anti-Semitic measures on the grounds that they would weaken Germany domestically and isolate it abroad. Put on trial at Nuremberg, Schacht claimed that he had served in the government “to prevent the worst excesses of Hitler’s policies”, although some historians argue that he aided the Holocaust by expropriating Jewish property. He was acquitted at the trials, and later became an adviser to developing countries on economic development.

Schacht’s trajectory shows how unwise it is to attempt to label individuals as Nazi or not, or as pro-/anti-Semite. As I pointed out in my book, few scientists actually served, as Schacht did, in the Nazi administration; but few, too, spoke out publicly against the regime and actively opposed it, as Schacht did. Does this make them better or worse than him?

Either way, the fact that Schacht’s daughter and Goebbels’ family apparently think it is right that the family should get royalties for quoting him – in preference, indeed, to donating such proceeds to a Holocaust charity – should not shock us as much as it might. It’s a reminder that the legacy of the Nazi regime did not vanish either with Hitler’s death or with the fading of his generation. It is of a part with the widespread sense in Germany after the war that the case was now closed and that only the ardent Nazis had questions to answer.

Remember that the postwar trials were notoriously ineffectual, not just because it was extremely difficult and time-consuming thoroughly to investigate any allegation (let alone to prove it) but because many who supported the regime had little difficulty in obtaining the so-called Persilscheine or whitewash certificates of clearance. The most vociferous Nazis in the universities were dismissed without compensation, while others who had doubtless helped the regime were eased into early retirement. Hardly any of the scientists were incriminated. Pascual Jordan, for example, a Party member whose enthusiasm for National Socialism was such that its ideology even seeped into his physics, was issued a whitewash certificate by Werner Heisenberg, who attested that he had “never reckoned with the possibility that [Jordan] could be a [true] National Socialist” (rather inviting the question of what it would take to convince Heisenberg of that). Niels Bohr was less obliging: he replied to Jordan’s request for a letter of exoneration by sending the physicist a list of Bohr’s friends and relatives who had died in the camps.

The ‘denazification’ of German science was actively obstructed even by those who had had no sympathy with the National Socialists. The prevailing attitude was one of resentment at the intrusiveness of the occupying Allied authorities, which led to a closing of ranks and a feeling of solidarity between the most unlikely of bedfellows. Even relatively blameless individuals refused to condemn those who had been clearly implicated in the Nazi regime. Others drew an invidious parallel between the rooting out of Nazis after the war and the persecution of ‘non-Aryans’ before it. For Otto Hahn, denazification involved “attacks against the science of our nation”.

These prevarications and evasions during ‘denazification’ meant that it quickly became impossible to construct a clear picture of how the nazification of German society had proceeded. And it’s German historians who say this. Klaus Hentschel, for instance, has said that “It was one of the most depressing experiences I ever had as a historian to see reflected in the documents how very soon after 1945 the chance of coming to grips with the National Socialist regime was allowed to slip away, thus missing the opportunity to make a frank assessment of the facilitating conditions the regime had set.”

The prevailing attitude was not guilt or remorse, but self-pity and resentment at the indignities suffered in a defeated nation. Visiting Germany in 1947, Richard Courant, the mathematician who had been forced out of Göttingen in 1933, despairingly described its residents as “absolutely bitter, negative, accusing, discouraged and aggressive.” Hartmut Paul Kallmann, the postwar director of the former Kaiser Wilhelm Institute for Physical Chemistry in Berlin, who as a ‘non-Aryan’ had been dismissed under Fritz Haber’s directorship in 1933 and had worked for IG Farben during the war, wrote to the emigré Michael Polányi in 1946 saying that “the tough momentary situation [here] is deplored much more than the evil of the past 10 years… The masses still don’t know what a salvation the destruction of the Nazis was to the whole world and to Germany as well.” “It is a difficult problem with the Germans”, Margrethe Bohr told Lise Meitner two years later, “very difficult to come to a deep understanding with them, as they are always first of all sorry for themselves.” In 1947 the president of the polytechnic at Darmstadt complained that for some student “it seemed that the only thing the Nazis had done wrong was to lose the war.”

I think such sentiments still prevail in some quarters. From a certain generation of Germans, I have heard comments in response to my book even from evident anti-Nazis to the effect that “well of course you have no idea how hard it was for us.” In fact I have no doubts how hard it was for them. But such comments are offered as a shield against deeper reflection about the moral fallout. Sometimes it’s worse than that. Even for raising the question that folks like Heisenberg and Debye might have had questions to answer, I was called by one party a “cockroach” – and I can’t imagine for a moment that the similarity with the language used by the Nazis to dehumanize Easter Europeans and Jews could have been lost on that person. (This is not, let me stress, a specifically German response – I’m pretty sure that, as Ian Kershaw has intimated, what we saw in Germany before and after the war could have happened anywhere, mutatis mutandis. We are certainly not free from such language in Britain today, as we have sadly discovered recently.)

So no, there is really nothing so strange or surprising about the Schacht/Goebbels response. I am proud that Bodley Head is standing up to it.

Condensed-matter physics gets its hands dirty

Here is the original version of my leader for Nature Materials, which I want to put up here to acknowledge the insightful input from Bob Cava and Bertram Batlogg - N Mat's leader style doesn't permit direct quotes, so I had to paraphrase their words.

_________________________________________________________

Is condensed-matter physics becoming more materials-oriented? Or is this just a new wrinkle in an old tradition?

Condensed-matter physics is becoming increasingly oriented towards materials science and engineering. That’s the conclusion reached by two Harvard physicists, Michael Shulman and Marc Warner, after analyzing the statistics of abstracts for the main annual (March) meeting of the American Physical Society since 2007. They enumerated key words used in abstracts to identify trends over the past eight years, and say that during this time the words that are increasing in popularity are often ones associated with specific types of material system, such as “layer”, “thin”, “organic”, “oxide” and indeed “material”. In contrast, words or (word fragments) with generally declining popularity include “superconduct” and “flux” (as well as, oddly, “science”).

What should we make of this? Probably not too much. As the authors are the first to point out, the analysis is preliminary and its timespan limited. It would be good to see it extended over a longer period and expanded to include, say, words in the abstracts of publications in Physical Review Letters, not to mention paying more attention to soft matter rather than primarily solid-state. The present results also paint a slightly confusing picture, taken at face value: condensed-matter physics (CMP) as a whole has been expanding if one judges from the gradual rise in the total number of abstracts submitted to CMP sessions of the March meeting, yet the “condensed matter” section of the preprint server arxiv has made up a shrinking proportion of the total during that time. There are various possible explanations for the discrepancy.

All the same, if it is qualitatively true that CMP has become more materials-focused, it’s worth asking why. Are established researchers in the field are altering the direction of their work away from abstract theoretical questions – what is the origin of high-temperature superconductivity, to take one obvious former preoccupation of theorists – and towards applications of particular materials systems? Or does that reflect a change in the interests of young researchers entering the field? Robert Cava of Princeton University doubts that it’s merely the latter, since old hands enjoy fresh challenges: “For old-timers like me, new areas are a way to use your stored knowledge to have insights that the youngsters miss.”

It is tempting to infer that researchers are just following the money: in this increasingly goal-oriented scientific climate, there may be better funding prospects for a project that can promise concrete applications at the end of the line. But might not the trend instead reflect the internal dynamics of the research community, so that funding follows areas deemed “hot” for other reasons? It’s almost sure to be a bit of both, as the example of graphene shows: there are high hopes for applications in electronics and composites, but much of the interest has come from the fundamental physics that this one-dimensional system seems to offer. More data on the dynamics and trends of funding priorities might help to separate cause and effect.

In any event, Bertram Batlogg at ETH in Zurich says that practical applications of the materials it studies has always been “in the best tradition of CMP”. Given the enormous contributions that the field has made to society – underpinning the technologies of smart phones and solar energy, say – it’s only natural that researchers should have an eye on ensuring that this tradition continues.

Shulman and Warner found that, in comparison to subjects such as atomic, molecular and optical physics, CMP changes fast: the statistics of key words are more volatile. Cava agrees that this is a feature of the field. “Occasionally, say once every 5-10 years, a subject comes up that is so new that many people work on it, because physicists are intrinsically enthusiastic and interested in new science.” He cites the case of pnictide superconductivity, which enjoyed its greatest popularity just before the period of this analysis. Superconductivity is now seeing another little surge of interest owing to topological superconductors.

“I believe that all fields have a natural life cycle”, says Cava. “They naturally go up in activity and then back down as people have had a chance to see what they can contribute and then move on to other new areas.” Shulman and Warner wonder if this cycle is shorter in CMP than elsewhere, perhaps because it can be stimulated by the discovery of a new material system (carbon nanotubes, say, or magnetic multilayers) but also because it can be hard to get at the high-lying fruits for many of these systems owing to the complexities of the many-body interactions they present – that, at least, seems to be what has kept a general theory of high-temperature superconductivity out of reach. What’s more, high-temperature superconductivity showed that there is a very low entry barrier for studying exciting new materials if they are relatively easy to synthesize: any lab well equipped with instrumentation can quickly and easily switch direction and still hope to make a useful contribution.

Might there also be a life cycle for CMP as a whole? The APS division was created only in 1978, from what was formerly the Division of Solid State Physics. Yet Shulman and Warner wonder if it still presents the kind of exciting challenges of 20-30 years ago. No one would claim, however, that the most demanding questions are all answered: perhaps some of them will need to await new techniques or new theoretical methods better able to accommodate complexity. And like chemistry, to some extent CMP creates its own subject: our inventiveness (or serendipity) with new materials systems prompts new questions. As Cava says, “to explore the complexity of the physics people have to think about and perform experiments on real materials. Each material has a different balance of the competing forces that give rise to the complexity of condensed matter physics, so each new material is an opportunity to learn new physics.”

This explains everything

Prospect preferred that I keep my short review of Steven Weinberg’s book To Explain the World behind the paywall. But he’s obliged by inviting further comment with his piece in the Guardian today, in which he talks both about the history of science and popular science writing. On both, his remarks are useful insofar as they encapsulate the worst of what drives me to despair when some (most definitely not all) scientists talk about these things.

The first thing to say is that Weinberg’s view of the history of science is not down to ignorance. It’s important to say this because that’s what it looks like. But no, Weinberg does not write Whiggish history because he doesn’t know what historians of science do these days, but specifically because he does know and disapproves of it. Yes, this high-energy physicist believes that historians don’t really know how to write history. It is hard to know why he nonetheless expresses “enormous respect for professional historians of science, from whom I have learned so much” – unless he means (as I suspect) that he is grateful to them for having dug all the facts out of the archive, but that he doesn’t believe they can be trusted to know what to do with them. Because Weinberg seems to have learned nothing from historians of science about how to be a historian.

If your view is that science was just kind of blundering around and dragging its feet until Newton’s Principia, then it’s perhaps not surprising if you conclude that the use of mathematics in science by ancients such as Plato and the Pythagoreans was “childish”. Again we have to understand that, while a remark like this coming from an undergraduate would simply indicate ignorance, from Weinberg it conveys something else. I am quite sure that he knows how incendiary such a claim is. But I fear that, in making it, he comes across like Jim Watson, evidently thinking that by saying the “outrageous” he is revealing himself as a bold and outspoken thinker whereas in fact he just sounds silly.

Talking of which… listen to this remark about science commentators and popularizers: “Ironically, as writers they were so much more popular than professional scientists that in many cases it is their comments on scientific research rather than reports of the research itself that were copies and recopied.” When you realise Weinberg is here writing about “the ancient world”, you see how anachronistic his whole perspective is. Those guys were kind of like, well, like Steven Weinberg, only in togas and sandals and doing really crappy maths.

His book is full of this sort of stuff. The generally uncritical reception it has got – with the splendid exception of Steven Shapin’s review in the WSJ – has left me rather depressed about how little general understanding there seems to be of what the history of science is about. So I can only imagine how professionals must feel; as one has said to me, “it's shocking that this sort of thing gets published by a major house”.

If Weinberg genuinely believes that pretty much the entire discipline has got things wrong, you’d think he would make the effort to explain why. But all he does in his book is shrug and say “I don’t buy it.” And all this stems from a total misunderstanding of what the historians are up to. Weinberg seems totally hung up on the idea that they are a nest of arch-relativists, convinced that the science we have today is no more valid than that of Aristotle or Roger Bacon, just a different story for different times. This says more about Weinberg than it does about the history of science. I think you’d have to look very hard to find a historian who truly believes that the theory of general relativity is no better than Newtonian gravity (and presumably therefore that it’s up to us whether or not to adjust our GPS satellite systems to take Einstein’s theory into account). As Weinberg puts it in his article (and now things really do get childish), “I argue with those historians who try to judge each era’s scientific work according to the standards of that era rather than of our own, as if science were not cumulative and progressive, as if its history could be written like the history of fashion.” In other words, he is not really interested in understanding why people once thought the way they did, but just whether they were “right” or “wrong”. A study of phlogiston theory would hold no interest for him, because it was wrong. Why think about wrong ideas? Well, as a scientist, he certainly has the luxury of not doing so. But then please, please don’t try to write history. The reason – one reason – to be interested in such things is that you have an interest in the history of ideas. Weinberg shows no curiosity about ideas that can’t be directly connected to ones we deem to be valid today. Someone with that view is going to be able only to convey a very limited picture of science to the general public.

Which brings me to science communication. Given Weinberg’s dismissive attitude to professional historians, I suppose it should come as no great surprise to discover his view of professional science writers. Like Richard Dawkins selecting The Oxford Book of Modern Science Writing, he only has eyes for fellow scientists who try to popularize what they do. It is essential that such people exist, and the best of them (like Dawkins and E. O. Wilson) have produced much of the best science writing. But the fact that, in an article on writing about science for the general public, Weinberg fails even to acknowledge the existence of people who do this professionally gives us a pretty fair picture of what he thinks about science communication. We have to assume that, like history, this is not something that need be done by specialists – it is best left to scientists themselves, since only they really understand science. They can, you know, just “take time off from their own research” to knock it out.

Like Weinberg? Well, The First Three Minutes is deservedly a classic. But it is helpful that Weinberg starts his piece by saying that “It is mathematics above all that present an obstacle to communication between professional scientist and the general public”, because it tells us from the outset that we needn’t take too seriously his thoughts on science communication. I am quite sure I am not alone when I say that, having written about science (particularly physical science) for more than 20 years, I have almost never found myself frustrated, in wishing to convey an idea or concept, by the fact that I cannot tell it in maths. Indeed, a wish to do so is almost invariably a good sign that the underlying ideas are not properly understood by the author. If scientists cannot communicate a concept without falling back on maths, they don’t truly grasp what it is they are trying to talk about. It is a failure of the communicator, not of the audience.

But even putting that aside, Weinberg’s insistent refrain about the role of maths in science betrays his extreme parochialism. This is reflected in To Explain the World, which is not about the history of science but about the history of physics, particularly celestial and terrestrial mechanics. He still takes the view, popular a century ago but long discarded by historians of science, that no science has really grown up until it becomes thoroughly mathematical. I’m not even sure that there are many physicists who still cling to this absurd notion. It reveals a total lack of understanding of chemistry, materials science, evolutionary biology and cell biology, to name just a few areas. Of course, mathematical and quantitative models are important in all these areas. But they don’t define them in the same way as they do most of physics. Weinberg’s is the kind of thinking that says chemistry only became a proper science (and at the same time, an obsolete one) when quantum theory explained the structure of the atom and the nature of the chemical bond. And that, to use a popular physics slogan, is not even wrong.

This sort of parochialism is reflected in Weinberg’s list of “13 best science books for the general reader”. Only one of them is by a professional science writer (Timothy Ferris, who certainly deserves that place), and nine of them are about physics – and cosmological, nuclear or fundamental physics at that. No chemistry; no surprise. The shortage of women in Weinberg’s list is not because, as he tells us, “women were not welcome in science through most of its history”, but because he does not seem interested in the work of the many excellent science writers who happen to be female. Because they aren’t real scientists, you see. And so there is no room for the likes of Georgina Ferry, Elizabeth Kolbert, Margaret Wertheim, Dava Sobel, Deborah Blum, Gabrielle Walker... Instead, we get Lisa Randall – not, I suspect, because she is a particularly gifted communicator of science (sadly she is not), but because she works in theoretical physics. (If he’d wanted to limit himself to that, he could at least have chosen Janna Levin, who really can write well.)

The great thing about writing books, Weinberg says, is that it has given him “the opportunity of leaving for a while the ivory tower of theoretical physics research, and making contact with the world outside.” He should do it more often.

Looking for the science vote

Very interesting to see in Nature the changes in British readers’ voting intentions from 2010 to the forthcoming UK election in May. In a nutshell: once a Tory, always a Tory but there’s a big leaching from the middle/left parties to “Don’t know”, plus a substantial boost to the Greens from the same source. I don’t know how representative this of the population as a whole, but it unsettles me to see such a big uncommitted block, and this is why.

I fully support Jenny Rohn and Stephen Curry’s initiative to get science firmly on the political agenda (Science is Vital), but I’m concerned that it not become a call to vote simply on the basis of who you think will do the best job for science (which I'm sure is not Jenny and Stephen's intention). I have heard that kind of single-issue politics already from one or two prominent voices of science, and it troubles me deeply. While obviously wanting everyone to vote the way I do (and accepting that some will think I’m deluded in that choice), I feel that voters ought ideally be making up their minds in the basis of which party will try to create the fairest, most tolerant, egalitarian, responsible and healthy society, and not simply which party is going to perform best on a single issue – even one as important as science. If I felt that the party closest to my political sympathies was failing to do enough for science, I would lobby them to do better, and not switch allegiances on those grounds alone. After all, none of the major parties is likely to deny the importance of science, even if they won’t all back up their words with actions to the same degree. And without wishing to sound too melodramatic, it was by telling themselves that they were doing what was "best for German science" that many German scientists were able to salve their consciences during the Nazi regime.

The Saga of the Sunstones

In the Dark Ages, the Vikings set out in their longships to slaughter, rape, pillage, and conduct sophisticated measurements in optical physics. That, at least, has been the version of horrible history presented recently by some experimental physicists, who have demonstrated that the complex optical properties of the mineral calcite or Iceland spar can be used to deduce the position of the sun – often a crucial indicator of compass directions – on overcast days or after sunset. The idea has prompted visions of Norse raiders and explorers peering into their “sunstones” to find their way on the open sea.

The trouble is that nearly all historians and archaeologists who study ancient navigation methods reject the idea. Some say that at best the fancy new experiments and calculations prove nothing. Historian Alun Salt, who works for UNESCO’s Astronomy and World Heritage Initiative, calls the recent papers “ahistorical” and doubts that the work will have any effect “on any wider research on navigation or Viking history”. Others argue that the sunstone theory was examined and ruled out years ago anyway. “What really surprises me and other Scandinavian scholars about the recent sunstone research is that it is billed as news”, says Martin Rundkvist, a specialist in the archaeology of early medieval Sweden.

This debate doesn’t just bear on the unresolved question of how the Vikings managed to cross the Atlantic and reach Newfoundland without even a compass to guide them. It also goes to the heart of what experimental science can and can’t contribute to an understanding of the past. Is history best left to historians and archaeologists, or can “outsiders” from the natural sciences have a voice too?

What a saga

The sunstone hypothesis certainly isn’t new. It stems largely from a passage in a thirteenth-century manuscript called St Olaf’s Saga, in which the Icelandic hero Sigurd tells King Olaf II Haraldsson of Norway where the sun is on a cloudy day. Olaf checks Sigurd’s claim using a mysterious sólarsteinn or sunstone:
Olaf grabbed a Sunstone, looked at the sky and saw from where the light came, from which he guessed the position of the invisible Sun.

An even more suggestive reference appears in another thirteenth-century record of a Viking saga, called Hrafns Saga, which gives a few more clues about how the stone was used:
the weather was sick and stormy… The King looked about and saw no blue sky… then the King took the Sunstone and held it up, and then he saw where the Sun beamed from the stone.

In 1967 Danish archaeologist Thorkild Ramskou suggested that this sunstone might have been a mineral such as the aluminosilicate cordierite, which is dichroic: as light passes through, rays of different polarization are transmitted by different amounts, depending on the orientation of its crystal planes (and thus its macroscopic facets) relative to the plane of polarization. This makes cordierite capable of transmitting or blocking polarized rays selectively – which is how normal polarizing filters work. (Ramskou also suggested that the mineral calcite, a form of calcium carbonate, would work as a sunstone, based on the fact that calcite is birefringent: rays with different polarizations are refracted to different degrees depending on the orientation with respect to the crystal planes. But that’s not enough, because calcite is completely transparent: changing its orientation makes no difference to how much polarized light passes through. You need dichroism for this idea to work, not birefringence.)

Because sunlight becomes naturally polarized as it is scattered in the atmosphere, if cordierite is held up to sunlight and rotated it turns darker, becoming most opaque when the crystal planes are at right angles to the direction of the sun’s rays. Even if the sun itself is obscured by mist or clouds and its diffuse light arrives from all directions, the most intense of the polarized rays still come straight from the hidden sun. So if a piece of dichroic mineral is held up to the sky and rotated, the pattern of darkening and lightening can be used to deduce, from the orientation of the crystal’s facets (which reveal the orientation of the planes of atoms), the direction of the sun in the horizontal plane, called its azimuth. If you know the time of day, then this angle can be used to calculate where north lies.

Ramskou pointed out that polarizing materials were once used in a so-called Twilight Compass by Scandinavian air pilots who flew over the north pole. Their ordinary compasses would have been useless then, but the Twilight Compass allowed them to get their bearings from the sun. So maybe the Vikings did the same out on the open sea? Might they have chanced upon this handy property of calcite, found in abundance on Iceland? Perhaps all Viking ships set sail with a sunstone to hand, so that even on overcast or foggy days when the sun wasn’t visible they could still locate it and find their bearings.

The idea has been discussed for years among historians of Viking navigation. But only recently has it been put to the test. In 1994, astronomer Curt Roslund and ophthalmologist Claes Beekman of Gothenburg University showed that the pattern of darkening produced by a dichroic mineral in diffuse sunlight is too weak to give a reliable indication of the sun’s location. They added that such a fancy way to find the hidden sun seems to be unnecessary for navigation anyway, because it’s possible to locate the sun quite accurately with the naked eye when it is behind clouds from the bright edges of the cloud tops and the rays that emanate from behind the cloud. The sunstone idea, they said, “has no scientific basis”.

That was merely the opening sally of a seesawing debate. In 2005, Gabór Horváth at the Loránd Eötvös University in Budapest, a specialist in animal vision, and his colleagues tested subjects using photographs of partly cloudy skies in which the sun was obscured, and found that they couldn’t after all make a reasonably accurate deduction of where the sun was. Two years later Horváth and collaborators measured the amount and patterns of polarization of sunlight in cloudy and foggy skies and concluded that both are after all adequate for the “polarizer” sunstones to work in cloudy skies, but not necessarily in foggy skies. All this seemed enough to rehabilitate the plausibility of the sunstone hypothesis. But would it work in practice?

Double vision

Optical physicists Guy Ropars and Albert Le Floch at the University of Rennes had been working for decades on light polarization effects in lasers. In the 1990s they came across the sunstone idea and the objections of Roslund and Beekman. While Horváth’s studies seemed to show that it wasn’t after all as simple as they had supposed to find the sun behind clouds, Ropars and Le Floch agreed with their concern that the simple darkening of a dichroic crystal due to polarization effects is too weak to do that job either. The two physicists also pointed out that Ramskou’s suggestion of using birefringent calcite this way won’t work. But, they said, calcite has another property that presents a quite different way of using it as a sunstone.

When a calcite crystal is oriented so that a polarized ray strikes at right angles to the main facet of the rhombohedral crystals, but at exactly 45 degrees to the optical axis of the crystal – at the so-called isotropy point – it turns out that the light in the rays at this position are completely depolarized. As a result, it’s possible to find the azimuth of a hidden sun by exploiting the sensitivity of the naked eye to polarized light. When polarized white light falls on our eye’s fovea, we can see a pattern in which two yellowish blobs fan out from a central focus within a bluish background. This pattern, called Haidinger’s brushes, is most easily seen by looking at a white sheet of paper illuminated with white polarized light, and rotating the filter. We can see it too on a patch of blue sky overhead when the sun is near (or below) the horizon by rotating our head. By placing a calcite crystal in the line of the polarized rays oriented to its isotropy point relative to the sun’s azimuth, the polarization is removed and Haidinger’s brushes vanish. Comparing the two views by moving the crystal rapidly in and out of the line of sight, the researchers found that the sun’s azimuth can be estimated to within five degrees.


Haidinger’s brushes: an exaggerated view.

But it’s a rather cumbersome method, relies on there being at least a high patch of unobstructed sky, and would be very tricky on board a pitching ship. There is, however, a better alternative.

Because calcite is birefringent, when a narrow and partially polarized light ray passes through it, the ray is split in two, an effect strikingly evident with laser beams. One ray behaves as it would if just travelling through glass, but the other is deviated by an amount that depends on the thickness of the crystal and the angle of incidence. This is the origin of the characteristic double images seen through birefringent materials. And whereas Roslund and Beekman had argued that changes in brightness for a dichroic substance rotated in dim, partially polarized light are likely to be too faint to distinguish, the contrast between the split-beam intensities as calcite is rotated are much stronger and easier to spot. “The sensitivity of the system is then increased by a factor of about 100”, Ropars explains. At the isotropy point, the two rays will have exactly the same brightness, regardless of how polarized the light is. This means that, if we can accurately judge this position of equal brightness, the orientation of the crystal at that point can again be used to figure out the azimuth from which the most intense rays are coming.



Double images and split laser beams in calcite, due to birefringence.

The human eye happens to be extremely well attuned to comparing brightness contrasts of fairly low-level lighting. So the researchers’ tests using partially polarized light shone through a calcite crystal showed that, under ideal conditions, the direction of the light rays could be estimated to within 1 degree even for low overall light intensities, equivalent to a sun below the horizon at twilight. The method, they say, will work even up to the point where the first stars appear in the sky.

Showing all this is the lab is one thing, but can it be turned into a navigational instrument? Ropars, Albert Le Floch and their coworkers have already made one. They call it the Viking Sunstone Compass.

It’s a rather beautiful wooden cylinder with a hole in the top, through which light falls from the zenith of the sky onto a calcite crystal attached to a rotating pivot turned by a little handle on the lid. There’s a gap in the side through which the observer looks at the two bright spots projected from the crystal. “You simply rotate the crystal to equalize the intensities of the beams”, says Ropars. A pointer on the lid then indicates the orientation of the crystal and the azimuth of the sun, from which north can be deduced by taking into account the time of day. Ropars says that, even though of course the Vikings lacked good chronometers, they seem to have known about sundials. What’s more, studies have shown that people’s internal body clocks (their circadian rhythm) can enable us to estimate the time of day to within about a quarter of an hour.


The Viking Sunstone Compass made by researchers at the University of Rennes. Note the double bright spots in the cavity.

But never mind Vikings – the Rennes team could probably make a mint by marketing these elegant devices as a luxury item for sailors. Ropars says that a US company is now hoping to commercialize the device based on their prototype.

All at sea

When the findings were reported, they spawned a flurry of excited news headlines, many claiming that the mysteries of Viking navigation had finally been solved. It’s not surprising, for the image of brawny Vikings making use of such a brainy method is irresistible. But what, in the end, did the experiments really tell us about history?

There’s nothing in principle that might have prevented the ancient Greeks from developing steam power or microscopes. We are sure that they didn’t because there is absolutely no evidence for it. So an experiment demonstrating that, say, ancient Greek glass-making methods allow one to make the little glass-bead microscope lenses used by Antoni van Leeuwenhoek in the seventeenth century is historically meaningless. What, then, can we conclude about Viking sunstones?

Because the Viking voyages between the ninth and eleventh centuries were so extensive – they sailed to the Caspian Sea, across the Mediterranean to Constantinople, and over the Atlantic to North America – there is a pile of archaeological and historical research on how on earth they did it. The prevailing view is that, in the Dark and Middle Ages, as much sailing as possible was done in sight of land, so that landmarks could guide the way. But of course you can’t cross the Atlantic that way. So if no land was in sight, sailors used environmental signposts: the stars (the Vikings knew how to find north from the Pole Star), the sun and moon, winds and ocean currents. They also relied on the oral reports of previous voyagers to know how long it should take to get to particular places.

What if none of these clues was available? What did they do if becalmed in the open sea on a cloudy day? Well, then they admitted that they were lost – as they put it, hafvilla, “wayward at sea”. The written records indicate that under such circumstances they would convene to discuss the problem, relying on the instincts of the most experienced sailors to set a course.

However, some archaeologists and historians, like Ramskou, have argued that they could also have used navigational instruments. The problem is that there is precious little evidence for it. The Scandinavian coast is dotted with Viking ship finds, some of them wrecks and others buried to hold the dead in graves. But not one has provided any artifacts that could be navigational tools. Nevertheless, the archaeological record is not entirely barren. In 1948 a Viking-age wooden half-disk carved with sun-like serrations was unearthed under the ruins of a monastery at Uunartoq in Greenland. It was interpreted by the archaeologist Carl Sølver as a navigational sundial, an idea endorsed by Ramskou in the 1960s. More recently another apparent wooden sundial was found at the Viking site on the island of Wolin, off the coast of Poland in the Baltic. A rectangular metal object inscribed in Latin, found at Canterbury and tentatively dated to the eleventh century, has also been interpreted as a sundial, while a tenth-century object from Menzlin in Germany might be a nautical weather-vane.



A Viking ship grave at Oseberg in Norway, and the Uunartoq Viking sundial.

So the “instrumental school” of Viking navigation has a few tenuous sources. But no sunstones. That hasn’t previously deterred the theory’s champions. One of them was Leif Karlsen, an amateur historian whose 2003 book Secrets of the Viking Navigators announced his convictions in its subtitle: “How the Vikings used their amazing sunstones and other techniques to cross the open ocean”. One problem with such a bold claim is that the sunstone hypothesis had already been carefully examined in 1975 by the archaeologist Uwe Schnall, who argued that not only is there no evidence for it but there is no clear need either. “Since then, to my knowledge, no research has contradicted this conclusion”, says Willem Mörzer Bruyns, a retired curator of navigation at the Netherlands Maritime Museum in Amsterdam.

In making his case, however, Karlsen presented a new exhibit. In 2002, just as his book was being completed, archaeologists discovered a calcite crystal in the remains of a shipwreck offshore from the Channel Island of Alderney. It has been made misty by centuries of immersion in seawater and abrasion by sand, but it still has the familiar rhombohedral shape. Finally, tangible proof that sailors carried sunstones! Well, not quite. Not only is it totally unknown why the crystal was on board, but the ship is from Elizabethan England, not the Viking age.


The Alderney “sunstone”.

All the same, Ropars and colleagues claim that it supports their theory that these crystals were used for navigation. They point out, for example, that it was found close to a pair of navigational dividers. But, says Bruyns, “navigational instruments were kept in the captain’s and officers’ quarters, where their non-navigational valuables were also stored.” All the same Bruyns is sympathetic to the idea that, rather than being a primary navigational device, the crystal might have been used to correct for compass errors caused by local magnetic variations (such as proximity to iron cannons), which was done at that time by looking at the sun’s position on the horizon when it rose or set. Ropars points out that birds use the same recalibration of their magnetic sensors using polarization of sunlight at sunrise and sunset. “We’re now looking for possible mentions of sunstones in the historical Navy reports of the 15th and 16th centuries”, he says. But however intriguing that idea is, it has no bearing on a possible use of sunstones for navigation in the pre-compass era. “The Alderney finding is from a completely different period and culture to the Vikings”, Ropars acknowledges.

Finding the right questions

One way to view the latest work on sunstones is that it could at least have ruled out the hypothesis in principle. But don’t historians need a good reason to regard a hypothesis as plausible in the first place, before they get concerned about whether it is possible in practice? Otherwise there is surely no end to the options one would need to exclude. And there is the difficult issue of the documentary record. Lots of what went on a millennium and more ago was not written down, and much of what was is now lost. All the same, there is a rich literature, at least from the Middle Ages, of the techniques and skills of trades and professions, while early pioneers of optics like Roger Bacon and Robert Grosseteste in the thirteenth century offer a pretty extensive summary of what was then known on the subject. It’s not easy to see how they would have neglected sunstones, if these were widely used in navigation. Ropars says that the Icelandic sagas aren’t any longer the only textual source for sunstones, for the Icelandic medieval historian Arni Einarsson pointed out in 2010 that sunstones are also mentioned in the inventory lists of some Icelandic monasteries in the fourteenth and fifteenth centuries, where they were apparently used as time-keeping tools for prayer sessions. But monks weren’t sailors.

The basic problem, says Salt, is that scientists dabbling in archaeology often try to answer questions that, from the point of view of history and anthropology, no one is asking. This has been a bugbear of the discipline of archaeoastronomy, for example, in which astronomers and others attempt to provide astronomical explanations of historical records of celestial events, such as darkening of the skies or the appearance of new stars and other portents. Explanations for the Star of Bethelem have been particularly popular, but here too Salt thinks that it is hard to find any examples of a historically interesting question being given a compelling answer. [See, e.g. J. British Astron. Assoc. 114, 336; 2004]. One of the most celebrated examples, also revolving around optical physics, was the suggestion by artist David Hockney and physicist Charles Falco that painters in the Renaissance such as Jan van Eyck used a camera obscura to achieve their incredible realism. The theory is now generally discounted by art historians.

“‘Could the Vikings have used sunstones’ is a different question to ‘did the Vikings use sunstones”, which is what most historians are interested in,” says Salt. “A paper that tackles a historical problem by pretty much ignoring the historical period your artefact comes from seems to me to be eccentric.” Ropars agrees that “experimental science can exclude historical hypotheses, but isn’t sufficient to validate them.” But he is optimistic about the value of collaborations between scientists and historians or archaeologists, when the historical facts are sufficiently clear for the scientists to develop a plausible model of what might have occurred.

Could it be, though, that we’re looking at the sunstone research from the wrong direction? One of its most attractive outcomes is not an answer to a historical question, but a rich mix of mineralogy, optics and human vision that has inspired the invention of a charming device which, using only methods and materials accessible to the ancient world, enables navigation under adverse conditions. It would be rather lovely if the modern “Viking Sunstone Compass” were to be used to cross the Atlantic in a reconstructed Viking ship, as was first done in 1893. It would prove nothing historically, but it would show how speculations about what might have been can stimulate human ingenuity. And maybe that’s enough.


The reconstructed Viking ship the Sea Stallion sets sail.

Further reading
J. B. Friedman & K. M. Figg (eds), Trade, Travel and Exploration in the Middle Ages: An Encyclopedia, from p. 441. Routledge, London, 2000.

A. Englert & A. Trakadas (eds), Wulfstan’s Voyage, from p.206. Viking Ship Museum, Roskilde, 2009.

G. Horváth et al., Phil Trans. R. Soc. B 366, 772 (2011).

G. Ropars, G. Gorre, A. Le Floch, J. Enoch & V. Lakshminarayanan, Proc. R. Soc. A 468, 671 (2011).

A. Le Floch, G. Ropars, J. Lucas, S. Wright, T. Davenport, M. Corfield & M. Harrisson, Proc. R. Soc. A 469, 20120651 (2013).

G. Ropars, V. Lakshminarayanan & A. Le Floch, Contemp. Phys. 55, 302 (2014).

____________________________________________________________________

Note: A version of this article appears in New Scientist this week. A pdf of this article is available on my website here.