Thursday, September 14, 2017

Bright Earth in China

This is the introduction to a forthcoming Chinese edition of my book Bright Earth.


I have seen the Great Wall, the Forbidden City, Hangzhou’s wondrous West Lake, the gardens of Suzhou and the ancient waterworks of Dujiangyan in Sichuan. But somehow my travels in China have never yet brought me to Xi’an to see the tomb of the First Emperor Qin Shi Huangdi and his Terracotta Army. It is most certainly on my list.

But I know that none of us now can ever see the ranks of clay soldiers in their full glory, because the paints that once adorned them have long since flaked off the surface. As I say in Bright Earth of the temples and statues of ancient Greece, they leave us with the impression that the ancient world was more drab than was really the case. These statues were once brightly coloured, as we know from archaeological work on the excavations at Xi’an – for a few fragments of the pigments still adhere to the terracotta.

Some of these pigments are familiar from elsewhere in the ancient world. Red cinnabar, for example – the mineral form of mercury sulfide – is found throughout Asia and the Middle East during the period of the Qin and Han dynasties. Cinnabar was plentiful in China: Sha’anxi alone contains a fifth of the country’s reserves, and it was mined for use not just in pigments but in medicines too. Chinese legend tells of one Huang An, who prolonged his life for at least 10,000 years by eating cinnabar, and Qin Shi Huangdi was said to have consumed wine and honey laden with the mineral, thinking it would prolong his life. (Some historians have speculated that it might instead have hastened his death, for it is never a good idea, of course, to ingest mercury.) According to the Han historian Sima Qian, the First Emperor’s tomb contained a scale model of his empire with rivers made of mercury – possibly from the ancient mines in Xunyang county in southern Sha’anxi.

But some of the pigments on the Terracotta Army are unique to China. This is hardly surprising, since it is widely acknowledged now that chemistry in ancient China – alchemy, as it was then – was a sophisticated craft, used to make a variety of medicines and other substances for daily life. This was true also of ancient Egypt, where chemistry produced glass, cosmetics, ointments and colours for artists. One of the most celebrated colours of the Egyptians is simply now called Egyptian blue, and as Bright Earth explains, it is probably an offshoot of glass-making. It is a blue silicate material, its tint conferred by the element copper. China in the Qin and Han periods, and earlier during the Warring States period of around 479-221 BC, did not use Egyptian blue, but had its own version, now known as Han blue or (because after all it predates the Han) simply Chinese blue. Whereas Egyptian blue has the chemical name calcium copper silicate, Chinese blue substitutes calcium for the element barium.

The ancient Chinese chemists discovered also that, during the production of this blue pigment they could create a purple version, which has the same chemical elements but combined in somewhat different ratios. That was a real innovation, because purple pigments have been hard to make throughout the history of the “invention of colour” – and in the West there was no good, stable purple pigment until the nineteenth century. Even more impressively, Chinese purple contains two copper atoms linked by a chemical bond, making it – of course, the makers had no knowledge of this – the earliest known synthetic substance with such a so-called “metal-metal bond”, a unit of great significance to modern chemists.

Although I’ve not seen the Terracotta Army, several years ago I visited Professor Heinz Berke of the University of Zurich in Switzerland, who has worked on analyzing their remaining scraps of pigment. Heinz was kind enough to give me a sample of the Chinese blue pigment that he had made in his laboratory; I have it in front of me now as I write these words. “The invention of Chinese Blue and Chinese Purple”, Heinz has written, “is an admirable technical-chemical feat [and an] excellent example of the positive influence of science and technology on society.”

My sample of modern Chinese blue, made by Heinz Berke (Zurich).

You can perhaps see, then, why I am so delighted by the publication of a Chinese edition of Bright Earth – for it combines three of my passions: chemistry, colour and China. I always regretted that I was not able to say more in the book about art outside the West, but perhaps one day I shall have the resolve to attempt it. The invention of colour in China has a rather different narrative, not least because the tradition of landscape painting – shanshuihua – places less emphasis on colour and more on form, composition and the art of brushwork. Yet that tradition has captivated me since my youth, and it played a big part in inducing me to begin exploring China in 1992. This artistic tradition, of course, in no way lessened the significance of colour in Chinese culture; it was, after all, an aspect of the correspondences attached to the system of the Five Elements (wu xing). And one can hardly visit China without becoming aware of the vibrancy of colour in its traditional culture, not least in the glorious dyes used for silk. I hope and trust, therefore, that Bright Earth will find plenty of resonance among Chinese readers.

Li Gongnian (c.1120), Winter Evening Landscape, and detail.

Wednesday, September 13, 2017

On being patriotic

It’s interesting now to go back (such a long time ago!) and read the White Paper released by the UK government in February on exiting the EU. It beggared belief then; it still does now.

Here is Theresa May, in her barely literate foreword, on the national sentiment: “after all the division and discord, the country is coming together.” It is hard to know which is worse: that she might genuinely think this is so, or that she knows it is not. Either way, she and her supporters have been assiduous in their efforts to prevent it.

An illustration of that is Norman Lamont’s article in the latest issue of Prospect. That it is moderately and elegantly worded makes it no less contemptible.

Lamont wants to perpetuate the picture of a “cosmopolitan elite” sneering at the cheap patriotism of the masses: “my cosmopolitanism is superior to your parochialism”. “Many intellectuals”, he says, “sneer at patriotism.”

So there’s your choice (once again): get behind Brexit and be a patriot and, or oppose it and be unpatriotic. Loyalty to country (and thereby to “democracy”), or loyalty to the EU: it’s one or the other.

This is frankly repulsive. It is the choice of the Daily Mail. Lamont quotes Siegfried Sassoon: “We write our lines out of our bones and out of the soil our forefathers cultivated.” Sassoon was of course writing in another time, before the nationalistic notion of a “blood and soil” fatherland had the connotations it does today. Lamont is writing now, and that he can unproblematically invoke a quote like this gives us an idea of the kind of sensibility we’re dealing with.

What Lamont illustrates, though, is well documented human behaviour: you must prove your in-group loyalty not merely by statement of it but by active and perhaps destructive rejection of the Other. Robert Sapolsky talks about it in his excellent new book Behave. In the extreme cases, gangland members establish their fealty by executing a rival, and child soldiers are trained to show their allegiance to the movement by their willingness to kill family members. And they do.

It is Us or Them, and nothing else. The notion that feelings of kinship can be multiple and overlapping seems alien to Lamont. The European identity, he asserts, is “extremely shallow.” He can speak for himself, but he has no business intimating that he speaks for us all. I share a sense of identity with Londoners (defying the ugly political climate that washes all around us in southern England). I share it with my local community, and with Englishness (yes! – more of this below), and Britishness, and also with Europeans, and with all of humanity. These feelings of kinship have different complexions in each case, but I don’t feel conflicted by them. The customs, languages, histories of Europeans are varied, and of course there are big differences between nations, just as there are between national regions. But there is also a great deal of shared culture and history, and when I am in (say) the Czech Republic I feel I am still in some sense within a familiar “homeland” that I can’t claim to feel in Tokyo. How small and withered Lamont’s sense of belonging must be if it is invoked only in the Cotswolds and not in Paris or Prague.

It’s a peculiarity of the Brexit vote that it has deepened my love of England and Britain. Deepened, that is, those aspects of it that I value all the more for seeing them vanish: the tolerance, good humour, open-mindedness, invention. More than once my partner and I have discussed emigrating to escape the poison and political apathy that has overtaken these isles. And each time I’ve resisted the idea because there is so much here that I love.

Shortly after the referendum, I found a copy of Defoe’s A Tour Thro’ the Whole Island of Great Britain abandoned on a wall on my way home, and picked it up – and felt immense sadness that the Union, still finding its feet in Defoe’s day, might soon be shattered. If that looks a bit less likely now, it is because the people of Scotland have more sense than those of England in letting economic interests be a part of decisions about trans-national partnership. All the same, Defoe’s book sharpened the pangs of feeling that my home nation has lost something it may never recover in my lifetime.

Lamont implies that we pro-Europeans (so he’s anti-European then?) don’t accuse Scottish nationalists of being xenophobic in the way we do English nationalists. Could this be because Scotland doesn’t seem to have a problem with the rest of Europe, perhaps? There is plenty of ahistorical sentimentality in Scottish nationalism, as well as some kneejerk (as opposed to totally understandable) anti-English sentiment. But can anyone blame Scotland for resenting the fact that, having voted overwhelmingly to stay in the EU, it is being dragged out of it by the English?

Lamont talks about a “fusion” of national identity into the “larger whole” of the EU. This is utter nonsense. Does anyone believe that France, Germany, Spain, Italy, have lost one whit of their national identity? Nor have they ceded their sovereign power. Which brings us to that notorious line in the White Paper: “Whilst Parliament has remained sovereign throughout our membership of the EU, it has not always felt like that.” Here’s the factual content of that sentence: “Parliament has remained sovereign throughout our membership of the EU.” The rest is intangible and subjective sentiment. It hasn’t felt like it to whom? In what way? But “feeling”, without any tangible benefit, is all Lamont can offer for a position that looks daily more catastrophic.

His yoking of Brexit to the health of democracy is particularly shameful. “To weaken the nation state is to weaken democracy,” he says. But if “Parliament has remained sovereign throughout our membership of the EU”, how has our nation state been weakened? Well, maybe it hasn’t. But maybe, to Lamont, it just felt like that. What does weaken a nation state is the collapse of its currency, the loss of trade deals, and the blind pursuit of an extremely divisive national policy, complete with a determination to label the half of the nation who didn’t want it traitors and “saboteurs”. What weakens democracy is to invoke ancient clauses that allow ministers to bypass parliament, and to attempt to impose on parliament decisions that the courts have, now on three occasions, ruled as incompatible with the laws of the nation, some of them put in place in the wake of the Civil War in order to ensure good and stable governance. What weakens democracy is a parliament so craven that it will not even stand up for its own rights (and obligations) on such occasions, making it necessary for a brave private citizen to do so. What weakens a nation is a government that refuses to condemn press attacks on the very legitimacy of the judiciary. What weakens a nation is to portray doubts about the wisdom of a course of action as a lack of patriotism.

If this is the best defence of Brexit that Lamont can offer, we are truly shafted.

If it is patriotic to take pride in the values that our neighbours used to praise us for, and to want to see one’s country economically healthy and presenting a confident face to the world, willing to engage in international institutions, then I am a patriot. But for Lamont, as for German nationalists in 1933, it seems that patriotism demands a rejection of internationalism: we can only “be ourselves” by rejecting Others. So if patriotism now demands that one endorses the pursuit – in the most shambolic manner imaginable – a course that is isolationist, financially and economically damaging (potentially ruinous) and, to most outside observers beyond the far-right fringes, is a barely comprehensible act of self-harm, all on the basis of sentimentality about what “feels” right, then you will have to count me out.

Wednesday, August 16, 2017

Teleportation redux

I’ve had an illuminating discussion with Mateus Araujo after he blogged about my piece for Nature on quantum teleportation. Mateus pointed out my error in suggesting that the protocol requires (rather than merely permits) the teleported state to be unknown, for which I’m very grateful. I’ve amended the story to put this right.

This doesn’t mean Mateus is now happy about all of the article – and given our (friendly and useful) exchange, I didn’t think he would be! He was also concerned that I was perpetuating the notion of some kind of magical, superluminal transmission of information between the original and target particles in teleportation. I was puzzled by that, because part of the point of the piece was to call out that very misconception. But then it transpired that Mateus’s concern stemmed from this paragraph:
“A common view is that quantum teleportation is a new way of transmitting information: a kind of high-speed quantum Wi-Fi. What’s amazing about it is that the quantum ‘information’ is ‘sent’ instantaneously — faster than light — because that is how two entangled particles communicate.”

I explained to Mateus that I had imagined this statement would be obviously intended ironically: that “amazing” refers to the breathless visions of the “common view”. It seems Mateus still feels I’m claiming that “something unobservable is going on faster than light, and that there is some kind of conspiracy by Nature to cover that up.” I’m not sure if Mateus thinks I still believe this, or simply that my piece still implies it regardless. So to be clear: I don’t think anything of the sort is happening at all. It seems to me that the causal language in which something here (Alice’s measurement) influences something there (the state of Bob’s particle) is precisely the wrong one to describe quantum entanglement. (I agree with David Mermin’s comment that entanglement presents us with correlations for which there is no “explanation”.)

This does raise the issue of whether rhetorical devices like irony should be used in science writing, where on general one tries to be as clear as possible (often to an audience whose first language is not English). It’s a question I do ponder over, and I’ll be writing about it soon for Chemistry World. I’ll say here only that I have been surprised (and not a little alarmed) before to discover that some scientists (not Mateus, however) seem unaware that such devices even exist. A little slice of Two Cultures Pie, perhaps?

Mateus originally stated that I also invoked in my article the “discredited notion of wavefunction collapse”. I made no reference to that at all, but he argues that it was implicit in the discussion: the idea of Alice’s actions having any kind of instantaneous consequence – perhaps better to say, instantaneous implication – for Bob’s particle requires wavefunction collapse. It was not my intention to do so, and perhaps by disavowing any sort of “instantaneous information transfer” in a physical sense I clear that up. But at any rate, to say that the notion of wavefunction collapse is now “discredited” (Mateus has suggested that no serious scientist now talks in those terms) is simply wrong. Indeed, the book chapter on which my article on the “measurement problem” (which Mateus liked) was based was taken seriously to task by another expert who decided that (my actual text to the contrary) it claimed to do away with collapse altogether.

The idea that decoherence completely “replaces” wavefunction collapse is not mainstream at all. Even some of those who think that it can – such as Roland Omnès, who says collapse can now be seen as “a convenience, not a necessity” – are careful to point out that decoherence doesn’t clear up everything. For it doesn’t explain the uniqueness of measurement outcomes. That, says Omnès, still needs to be added in what is essentially an axiomatic manner: unique facts exist.

So on the one hand I think her Mateus’s comment is an example of a more general tendency I’ve noticed among folks who think deeply about quantum foundations to suggest that, not only is their preferred interpretation the only one that makes sense, but it is the only one taken seriously at all.

On the other hand, this suggestion that “wavefunction collapse” is an obsolete idea raises the interesting question of what we mean by it in the first place. Some, of course – like Roger Penrose – think that this collapse is an actual physical process, just as decoherence is. And it is, moreover, a process that breaks the unitary behaviour rigorously observed by the Schrödinger equation (and which poses such dilemmas in connecting the theory to experience). This is not a mainstream view either, but it is a respectable one, pursued by some leading scientists – for it has the advantage, perhaps uniquely among quantum “interpretations”, of being empirically testable in principle.

For the likes of Bohr, wavefunction collapse was indeed a vague and problematic notion (or so it seems to me, though I’m wary of saying anything about what Bohr meant). But most physicists who talk about it don’t see it as some physical process; rather, it is a part of the mathematical formulation of quantum theory. It is, moreover, a necessary part: it amounts to applying the Born rule in order to make probabilistic predictions about the outcomes of experiments, and so it is needed to make any kind of connection at all between the theory and empirical experience. In other words, it’s a mathematical process. Some don’t think it is very helpful to talk about that process in the “physicalist” language of collapse; others have no problem in doing so. Everettians claim that the Many Worlds view does away with collapse at all, but then they face the problem of explaining why we need the Born rule to actually use quantum mechanics to make predictions. (Some, like Sean Carroll here, have claimed to derive the Born rule within the Many Worlds framework using choice theory, but this requires one to invoke the notion of a rational observer with a well-defined conscious experience that is continuous in time, which seems to be precisely what the Everettian view renders incoherent, unless it is simply imposed by fiat.)

So wavefunction collapse hasn’t gone away – though how nice it would be if we could make it do so.

Monday, March 27, 2017

Do you believe in miracles?

Tristan Casabianca has kindly drawn my attention to an article he published last year which discussed the case for the authenticity of the Turin Shroud – by which I mean the claim that it is not just an artifact made during the period traditionally ascribed to the life of Jesus Christ but that it was the cloth used to wrap his body between the Crucifixion and the Resurrection. It’s a thoughtful and provocative article, but I don’t agree with very much of it.

I won’t go into the evidence for and against the age and provenance of the Shroud here (see here instead). Suffice to say, it is still hotly contested, with several researchers arguing that the radiocarbon dating performed in 1988, which placed the Shroud in the 13th-14th century, was flawed in some respect or another. I’ve not seen convincing evidence to doubt that very careful study, but I do wish it could be repeated. I also think however that, based on the evidence we have to date, it is very hard to understand how the image of a bearded man was formed on the linen. It doesn’t seem to be painted on. It’s deeply intriguing, tantalizing question. In the interests of full disclosure, I don’t believe that Jesus of Nazareth was the resurrected son of God, and I find it extremely unlikely that this artifact which turned up in 14th-century France had anything to do with him. But that is just my opinion.

Casabianca’s article is concerned not so much with weighing up the arguments as with establishing the framework within which we should think about them. In particular, he takes issue with my comment in a 2008 column in Nature Materials that “the two attributes central to the shroud’s alleged religious significance – that it wrapped the body of Jesus, and is of supernatural origin – are precisely those neither science nor history can ever prove.” Casabianca in effect asks: really? Ever?

And in this much he is right: saying such and such can never happen is, when viewed philosophically, a contentious claim. It amounts to ruling out possibilities that we can’t be sure of. To take an extreme example: we might say that time travel contravenes the laws of physics as we currently know them, but can we really state as a philosophical absolute that there will never come a time when it becomes possible to travel back in time and witness at first hand the events that took place in Palestine around 33 AD? It sounds absurd to suggest such a thing (outside of Michael Moorcock’s splendid Behold The Man), but I’m not sure that a philosopher would accept such a ban as a rigorous principle, any more than we could deny the possibility that any other feature of (or indeed all of) our current understanding of the universe is utterly mistaken. I’m not sure that it is terribly meaningful to leave such possibilities open, though – in general when we say something is impossible, we mean it seems impossible according to our current understanding of the universe, and what more could we expect of such a statement than that?

But Casabianca is more specific. He says that of course we do come to accept some historical truths, even about the distant past. We accept that tomb KV62 discovered by Howard Carter is the tomb of Tutankhamen. So why should we consider it a theoretical impossibility that we could prove the Shroud to be the burial shroud of Jesus of Nazareth (even setting aside for the moment his theological status)?

Again, philosophically I don’t see how one could exclude that theoretical possibility. But could it ever happen, given what we have to go on? There is a possibility that Jesus of Nazareth was a real person – this seems rather likely to me, though I have no deep knowledge of the matter. How might we link this object to him? We could perhaps establish that the previous dating study was wrong, and find good reason to believe the Shroud was in fact made within, say, the two centuries bracketing the time Jesus is supposed to have lived. We might find pretty compelling evidence that it came from the Middle East, perhaps being able to localize it fairly well to Palestine, and also that it was probably used in a burial ritual. To be clear, none of this has been by any means proved right now, and some evidence argues against it – but in principle it seems plausible that it could happen.

What then? Casabianca offers no line of argument that could link this artifact to the person of Christ. Might we find his name inscribed on it somewhere? No, we will not. Might we be able to link the style of weaving to one specific to Nazareth at that time? If that were possible, surely it would have been done already. It seems to me that you have to think about what might be demonstrated historically in the light of the capacity of the artifact in question to hold the information required for that demonstration. I see no reason to think that the Shroud contains the kind of evidence needed to make such a definitive identification of provenance, and more than a random pot excavated in Birmingham can be linked to a specific Iron Age Brummie beer maker named Noddy. Whether one can exclude that as a “theoretical philosophical possibility” seems pretty irrelevant.

Casabianca goes on to point out that several historians do claim that there is good evidence for concluding that the Turin Shroud is the authentic burial wrapping of Jesus. And indeed they do. But it seems a very curious argument to say that it is valid to make this historical claim simply because some people do so. Simply, such claims are made; whether there are, or can be, adequate grounds for making them is another matter entirely.

Casabianca certainly goes too far, though, when he proposes that “to explain the image on the Turin Shroud, the Resurrection hypothesis is the most likely of all the hypotheses, even when compared with natural hypotheses.” There are several problems with this suggestion.

Casabianca suggests that it follows from “a historiographical approach (the ‘Minimal Facts Approach’)”, which I take to be some kind of Occam’s razor position. Even if you buy the usefulness in Occam’s razor for determining the preferred solution to a body of facts (and there is no philosophical or empirical justification for it), the idea becomes meaningless here. There is no calculus that allows you to make a quantitative comparison between a natural explanation of events that stays within the laws of physics and a supernatural explanation that does not. Is the explanation “God did it” economical because you can say it in three very short words? Or (as I think) does the idea that the laws of physics can be arbitrarily suspended by some unknown entity in fact incur an overhead of hypotheticals compared to which the demands of string theory look like a trifling concession? However you look at it, to afford supernatural explanations so casually doesn’t look like careful reasoning to me.

That’s all the more so given that there are so many unknowns and uncertainties about the Shroud image in the first place. Reports are contradictory and confused, technical issues are challenged, and quite frankly it has been pretty much impossible to perform careful, well checked science on this material at all, since the Roman church has made access to the samples so restricted. Put simply, we can’t be sure what facts we are proposing to explain.

Coming back to Casabianca’s contention, could science ever prove that the Shroud is of supernatural origin? Of course, scientists will rightly say that this is a semantic contradiction, since if new knowledge shows that what we have previously considered “supernatural” actually happens, it then just becomes part of the “natural”. But the real issue here is whether there could ever be incontrovertible evidence that such things as God, resurrections and divinely ordained virgin births may happen. Casabianca mentions the example of the stars spontaneously forming the sentence “God exists” in the sky. I for one am happy to say that, were that to happen, I would be given pause. My hierarchy of explanations would then be something like: It is a hoax or weird illusion; I have lost my mind; it is aliens; it is the Supreme Being saying hello. I have no problem of principle with working my way through that progression. Yes, I’m open to persuasion that God exists and that Christ rose from the dead and left his imprint in a cloth through supernatural means. Which rational person could not be?

But to accept such things on the basis of fuzzy and often rather poor science conducted on a jealously guarded scrap of old linen doesn’t seem terribly logical to me. To believe that a supreme being would have set us a puzzle of this kind, so hazily written and laced with red herrings, false trails and contradictions, to test our faith seems positively perverse. You would almost need to believe that He had set out not to challenge science but to traduce it. Such a God can’t be logically excluded from existence, but He does not interest me.

Tuesday, January 24, 2017

Killing the cat?

This graphic from New Scientist, and conversations last night at the Science Museum, got me thinking. Using Schrödinger’s cat as a way to illustrate the differences between interpretations of quantum theory is a nice idea. But it suffers from the flaw that challenges the entire thought experiment. In order to be able to talk about the scenario in quantum terms, we need to be able to express it in quantum terms. But we can’t, because “live cat” and “dead cat” are not well-defined quantum states.

What, you can’t tell a live cat from a dead cat? Nonsense! Well yes, it is; but that’s not we’re asking here. What quantum property is it, exactly, that characterizes the superposition state, and that will enable you, unambiguously and in a single shot, to distinguish the two classical states? Live and dead are not quantum variables, and I’m not at all sure that they can be correlated even in principle with quantum variables that can be placed in superposition states.

Schrödinger’s point was not, in any case, that these are two different states of a macroscopic object, but that they are logically exclusive states. The paradox lies not in “two states at once”, but in “two contradictory states at once”. He was pointing not to “weird behaviour” predicted by quantum theory, but to logical paradoxes.

And this is why the Many Worlds Interpretation doesn’t resolve the problem. Yes, it looks as though it does: both outcomes are true! As New Scientist puts it here, “The universe splits. Your cat is dead, but in a parallel world it remains alive.” (Or, as Rowan Hooper points out, vice versa.) But wait: your cat? Who is you? Whose cat is it in the other world?

Brian Greene, in The Hidden Reality, tells us: that is you too! They are both you. Oh, so that sentence reads “Your cat is dead, but your cat remains alive.” Greene isn’t troubled by the fact that this is not how “you” works. But nevertheless, this is not how “you” works.

David Deutsch and Max Tegmark say, ah language! What should we trust more, language or maths? Contingent sounds, or timeless equations? But here language is articulating something that underpins maths, which is logic. Schrödinger realized that, but his point seems to be forgotten (by some). I don’t have time to go into it here (my forthcoming book will), but individual identity is a logical construct. You can’t wish it away with fantasies about “other yous”. I am trying to resist the topical urge to suggest that the Many Worlds interpretation offers us “alternative facts”, but that is terribly hard to do. So folks, the second option here is far more problematic than it looks.

What about the first? Let me say first of all that in neither the Copenhagen nor the Many Worlds interpretation is the cat “simultaneously alive and dead”. Not only is there no way of expressing that in quantum mechanics (at least, no one has articulated one), but in any event the proper statement of the situation is that “We can say nothing about the state of the cat, other than that live and dead are both possible outcomes of an observation”. That might sound like a pedantic distinction, but it will not be possible to make sense of quantum mechanics without it.

Now, I would hesitate to call the Copenhagen interpretation the “standard” interpretation, since there is no consensus, nor even a majority view, about which is the correct interpretation of quantum mechanics, at least among those who think about foundational issues. What’s more, the “Copenhagen interpretation” is not a single thing: Heisenberg expressed it differently to Bohr, and Wheeler had his own view too, as did others. However, I think Bohr would have said something like this: after observation, we have acquired now information that has changed our view of the cat’s condition (assuming it can be expressed in quantum terms at all) from an indeterminate to a determinate one. Some Copenhagenists, such as Pascual Jordan, spoke of this in causative terms: our observations produce the results. In that view, it seems acceptable to say that “Your measurement killed the cat” (although since we cannot say that it was previously alive, we might need to say more strictly “Your measurement elicited a dead cat”). But I’m not at all sure that Bohr would have seen causation at work in the measurement, as if “wavefunction reduction” is a physical effect that kills the cat. (That’s really the third, “objective collapse” option, which is given the least problematic representation here.) I think Bohr might have said something along the lines that “Observation allows us to speak about the classical state of the cat. And look, it is a dead one!”

So, which way will you vote? Bear in mind, however, that there are other option available, not all of them mutually exclusive. And that you won’t be able to prove that you’re right, of course.

Tuesday, December 20, 2016

The EBS Club and how to blag your way in

Len Fisher is to blame for hooking me into the terrible narcissism that goes under the name of the EBS number. It’s the elite (pantomime boo and hiss!) version of the Kevin Bacon Game, or of the Erdős Number, by which you trace how many collaborations it takes to link you to actor Kevin Bacon (if you’re in the movies) or to mathematician Paul Erdős (if you’re in maths or some vaguely mathematical branch of science). There’s your E and B. The S is the fun one: how many links does it take to link you to doyens of Midlands heavy metal Black Sabbath? Your EBS number is the sum of the three.

Len explains the idea here. Elsewhere we’re told, rather flatteringly, that “To even have an Erdős-Bacon-Sabbath number puts you in quite an exclusive club” – one that includes the likes of Stephen Hawking, Richard Feynman and Brian May. Not surprisingly, it’s a club many will be keen to get into, and I sense a degree of fudging going on. Apparently as long as you’ve sat on a couch and chewed the cud with a film star, or been sampled in some portmanteau song, you can claim to have a B or an S. Or even a BS.

Being unable to resist this prod to my competitive bone (gland, more probably), I started pondering. I can get to an EBS of 15 without too much of a stretch – and that is by considering actual co-appearances in a movie or playing together in a band onstage, not (for example) appearing in the same chat show. I haven’t done a great deal of work on the Erdős number, other than to note that my coauthor Jean-Marie Lehn (“Supramolecular chemistry”, The New Chemistry, ed. N. Hall; Cambridge University Press, 2000) has an EN of 5 – so that makes mine no more than 6. It may be that I could do better via my PhD supervisor Bob Evans, as he’s a theoretical physicist.

For my Bacon Number, I had the questionable honour of appearing in an obscure little movie called The Undertakers (in which I played a member of rock band Hot Nun) with my old school friend Suri Krishnamma, who went on to become a well respected film director who has worked with the likes of Albert Finney (→ Marisa Tomei → Kevin Bacon) and Ray Liotta (→ Ryan Reynolds → Kevin Bacon). So I get a BN of 4.

For my Sabbath number, I could bend the rules and claim an SN of 2 via veteran BBC producer Tony Wilson, who produced both my 1985 Radio 1 session and every other major rock band of the 1970s and 80s, including at least one Sabbath session. But I think it’s more in the spirit of the thing to cite a gig I played in the same year with session guitarist Bruce Roberts, a legend on the Southampton music scene (whose band used to rehearse in the flat upstairs from the one we rehearsed in – you wouldn’t have wanted to live in Cranbury Place in 1984-5). Bruce played in the Jess Roden Band, among many others (he supported the likes of the Who and Alex Harvey and played with Ben E. King and Bryan Ferry). So thanks to him, I’m off and running: Jess Roden sung with Paul Rodgers on Paul Kossoff’s solo album Back Street Crawler, Rodgers temporarily took the place of the late Freddie Mercury in Queen, and from Queen it’s an easy step to Sabbath. So there’s a SN of 5.

I did consider trying via Portishead guitarist Adrian Utley, with whom I played in a gig in Bristol. But Adrian moves on other circles, so it’s a circuitous route. I do, however, still have a recording of that gig, and so you can hear what happens when the ridiculously talented Utley steps up to a solo and wipes everyone else from the stage. It was breathtaking.

So there you are: what I’d claim is a bona fide EBS number of 15. And what does that mean? The answer, of course, is very little. Plenty of top scientists have an Erdős number bigger than mine. More to the point, even if my BN and SN are valid, they come from fleeting associations that really say nothing about any putative “polymathic” skills. My encounters with Bruce and Adrian taught me only the difference between a musician kind of competent enough to get away with playing in public, and one who will make an impact – even a small one, in Bruce’s case – on the music business. As for my dramatic prowess in The Undertakers, the less said the better. These metrics are really an exercise in clinging to celebrity by one’s fingertips. Or to put it more positively, they offer a fun excuse to return to some of the more curious avenues of one’s path through life.

At the same time, this little exercise supports what Mark Granovetter said in 1973 about “the strength of weak ties” in social networks. Granovetter pointed out that many social networks consist of strongly connected local clusters – a group of closely connected individuals – linked to one another via weak ties. It’s these weak ties between communities, he said, that join them into a single network. I can’t claim to be deeply embedded in the movie or music communities in the way that I am in science – but my connections to those other networks exist through rather fleeting, one-off and not particularly profound links (Suri is a lovely bloke, but I haven’t seen him for many years; Bruce, who died earlier this year, probably wouldn’t have known me from Adam a few weeks after that gig.)

And while EBS numbers are not at all of the same constitution as the infamous h-index and other metrics used to rank scientists, I can’t help suspecting that much the same applies to those: they can point to a varied and impactful career (see Hawking or May), but they can also rely to a fair degree on chance, happenstance, and being in the right place at the right time.

All the same, I just want Ozzy to know that I’m up for a jam. Anything to give me a smaller EBS number than Adam Rutherford.

Thursday, December 15, 2016

More alternative heroes

It was fun to write this piece for Nautilus on who would have made some of the great discoveries in science if their actual discoverers had not lived. And very nice to see it is provoking discussion, as I’d hoped – there is nothing definitive in my suggestions. Here are two more case histories, for which there was not room in the final article.


Fullerenes – Wolfgang Krätschmer and Donald Huffman

In 1985, British spectroscopist Harry Kroto visited physical chemists Richard Smalley and Robert Curl at Rice University in Houston, Texas, to see if their machine for making clusters of atoms could produce some of the exotic carbon molecules Kroto thought might be formed in space. Their experiments led to the discovery of hollow, spherical molecules called C60 or buckminsterfullerene, and of a whole family of related hollow-shell carbon molecules called fullerenes. They were awarded the 1996 Nobel prize in chemistry for the work.

Fullerenes had been seen before 1985; they just hadn’t been recognized as such. They can in fact be formed in ordinary candle flames, but the most systematic experiments were conducted in 1982-3 by experimental physicist Wolfgang Krätschmer at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. Krätschmer had teamed up with physicist Donald Huffman of the University of Arizona, for they both were, like Kroto, interested in the constituents of interstellar space.

Huffman studied dust grains scattered through the cosmos from which stars may form. He and Krätschmer began collaborating in the 1970s while Huffman was on sabbatical in Stuttgart, and initially they looked at tiny particles of silicate minerals. But Huffman believed that some of the absorption of starlight by grains in the interstellar medium could be due to tiny particles of something like soot in the mix: basically, flakes of graphite-like carbon.

In 1982 he visited Krätschmer to carry out experiments in which they heated graphite rods in a vacuum and measured the light absorbed by the sooty debris. They made and saw C60, which absorbs ultraviolet light at a particular wavelength. But they didn’t realize what it was, and decided their apparatus was just making unintelligible carbon “junk”.

It wasn’t until the duo saw the paper by Kroto and colleagues in 1985 that the penny dropped. But if it hadn’t been for that, the interest of astronomers in interstellar dust would probably have returned scrutiny anyway to those experiments in Heidelberg, and the truth would have emerged. As it was, the graphite-vaporizing equipment of Krätschmer and Huffman offered a way to mass-produce fullerenes more cheaply and simply than the Rice cluster machine. Once this was understood in 1990, fullerene research exploded worldwide.

Continental drift – Roberto Mantovani, or…

There are discoveries for the time seems right, and others for which it’s just the opposite. For one reason or another they are rejected by the prevailing scientific opinion, offering us the retrospective, appealingly tragic tale of the lone maverick who was spurned only vindicated much later, perhaps posthumously. That’s pretty much how it was for Alfred Wegener’s theory of continental drift. In the 1930s, Wegener, a German meteorologist (so what did he know about geology?), proposed that the Earth’s surface was not fixed, but that the continental land masses wander over time into different configurations, and were in the distant past disposed far from where they stand today. To doubt the evident solidity of the planetary surface seemed absurd, and it wasn’t until the discovery of seafloor spreading – the formation of fresh ocean crust by volcanic activity – in the 1960s that continental drift became the paradigm for geology.

In such circumstances, it seems rather unlikely that anyone else would have come up with Wegener’s unorthodox idea in his own era. But they did. Not just one individual but several others imagined something like a theory of plate tectonics in the early twentieth century.

The most immediate sign of continental drift on the world map is the suspiciously close fit of the east coast of South America with the west coast of Africa. But that line of argument, advanced by American geologist Frank Bursley Taylor in 1908, seems almost too simplistic. Taylor got other things right too, such as the way the collision of continents pushes up mountain ranges. But his claim that the movements were caused by the close approach of the moon when it was suddenly captured by the Earth in the Cretaceous period was rather too baroque for his contemporaries.

In 1911, an amateur American geologist named Howard Baker also proposed that the continents are fragments of an epicene supercontinent that was torn apart. His mechanism was even more bizarre than Taylor’s: the moon was once a part of the Earth that got ripped off by its rapid spinning, and the continents moved to fill the gap.

In comparison, the theory of Italian geologist (and violinist) Roberto Mantovani, first published in 1889 and developed over the next three decades, was rather easier to swallow. He too argued that the continents were originally a single landmass that was pulled apart thanks to an expansion of the Earth driven by volcanic activity. Wegener acknowledged some “astonishingly close” correspondences between Mantovani’s reconstruction and his own.

All of these ideas contain tantalizing truths: breakup of an ancient supercontinent (now called Pangea), opening of ocean basins, mountain building and volcanism as the driving force. (Even Baker’s idea that the moon was once a part of the Earth is now widely believed, albeit for totally different reasons.) But like a reconstruction of Pangea from today’s map, the parts didn’t fit without gaps, and no one, including Wegener, could find a plausible mechanism for the continental movements. If we didn’t have Wegener, then Mantovani, or even Taylor or Baker, could step into the same foundational narrative of the neglected savant. All intuited some element of the truth, and their stories show that there’s often an element of arbitrariness in what counts as a discovery and who gets the credit.