Friday, September 19, 2008

Opening the door to Hogwarts
[This is how I originally wrote my latest story for Nature’s online news. It is about another piece of creative thinking from this group at Shanghai Jiao Tong University. I was particularly struck by the milk-bottle effect that John Pendry told me about – I’d never thought about it before, but it’s actually quite a striking thing. (The same applies to water in a glass, but it’s more effective with milk.) John says that it is basically because, as one can show quite easily, no light ray can pass through the glass wall that does not also pass through some milk.

Incidentally, I have to suspect that John Pendry must be a candidate for some future Nobel for his work in this area, though probably not yet, as the committee would want to see metamaterials prove their worth. The same applies to Eli Yablonovitch and Sajeev John for their work on photonic crystals. Some really stimulating physics has come out of both of these ideas.

The photo, by the way, was Oliver Morton’s idea.]

Scientists show how to make a hidden portal

In a demonstration that the inventiveness of physicists is equal to anything fantasy writers can dream up, scientists in China have unveiled a blueprint for the hidden portal in King’s Cross railway station through which Harry Potter and his chums catch the train to Hogwarts.

Platform Nine and Three Quarters already exists at King’s Cross in London, but visitors attempting the Harry Potter manoeuvre of running at the wall and trusting to faith will be in for a rude shock.

Xudong Luo and colleagues at Shanghai Jiao Tong University have figured out what’s missing. In two preprints, they describe a method for concealing an entrance so that what looks like a blank wall actually contains invisible openings [1,2].

Physicist John Pendry of Imperial College in London, whose theoretical work laid the foundations of the trick, agrees that there is a whiff of wizardry about it all. “It’s just magic”, he says.

This is the latest stunt of metamaterials, which have already delivered invisibility cloaks [3] and other weird manipulations of light. Metamaterials are structures pieced together from ‘artificial atoms’, tiny electrical devices that allow the structure to interact with light in way that are impossible for ordinary substances.

Some metamaterials have a negative refractive index, meaning that they bend light the ‘wrong’ way. This means that an object within the metamaterial can appear to float above it. A metamaterial invisibility shield, meanwhile, bends light smoothly around an object at its centre, like water flowing around a rock in a river. The Shanghai group recently showed how the object can be revealed again with an anti-invisibility cloak [4].

Now they have worked out in theory how to hide a doorway. The trick is to create an object that, because of its unusual interactions with light, looks bigger than it really is. A pillar made of such stuff, placed in the middle of an opening in a wall, could appear to fill the gap completely, whereas in fact there are open spaces to each side.

Pendry and his coworker S. Anantha Ramakrishna demonstrated the basic principle in 2003, when they showed that a cylinder of metamaterial could act as a magnifying lens for an object inside it [5].

“When you look at a milk bottle, you don’t see the glass”, Pendry explains. Because of the way in which the milk scatters light, “the milk seems to go right to the edge of the bottle.” He and Ramakrishna showed that with a negative-refractive index metamaterial, an object in the bottle could be magnified on the surface.

And now Luo and colleagues have shown that an even more remarkable effect is possible: the milk can appear to be outside the bottle. “It’s like a three-dimensional projector”, says Pendry. “I call it a super-milk bottle.”

The Chinese team opt for the rather more prosaic term “superscatterer”. They show that such an object could be made from a metal core surrounded by a metamaterial with a negative refractive index [1].

The researchers have calculated how light interacts with a rectangular superscatterer placed in the middle of a wide opening in a wall, and find that, for the right choice of sizes and metamaterial properties, the light bounces back just as it does if there was no opening [2].

If someone passes through the concealed opening, they find, it becomes momentarily visible before disappearing again once they are on the other side.

So “platform nine and three-quarters is realizable”, the Shanghai team says. “This is terrific fun”, says Pendry. He feels that the effect is even more remarkable than the invisibility cloak, because it seems so counter-intuitive that an object can project itself into empty space.

But the calculations so far only show concealment for microwave radiation, not visible light. Pendry says that the problem in using visible-light metamaterials – which were reported last month [6,7] – is that currently they tend to absorb some light rather than scattering it all into the magnified image, making it hard to project the image a significant distance beyond the object’s surface. So openings hidden from the naked eye aren’t likely “until we get on top of these materials”, he says.

1. Yang, T. et al. (2008).
2. Luo, X. et al. (2008).
3. Schurig, D. et al., Science 314, 977-980 (2006).
4. Chen, H., Luo, X., Ma, H. & Chan, C. T. (2008).
5. Pendry, J. B. & Ramakrishna, S. A. J. Phys.: Condens. Matter 15, 6345-6364 (2003).
6. Valentine, J. et al., Nature doi:10.1038/nature07247 (2008).
7. J. Yao et al., Science 321, 930 (2008).

Wednesday, September 17, 2008

Don't mention the 'C' word

I’m beginning to wonder whether I should be expecting the science police to come knocking on my door. After all, my latest book contains images of churches, saints, Jesus and the Virgin Mary. It discusses theology. And, goodness me, I have even taken part in a workshop organized by the Templeton Foundation. I am not sure that being an atheist will be a mitigating factor in my defence.

These dark thoughts are motivated by the fate of Michael Reiss, who has been forced to resign from his position as director of education at the Royal Society over his remarks about creationism in the classroom.

Now, Reiss isn’t blameless in all of this. Critics of his comments are right to say that the Royal Society needs to make it quite clear that creationism is not an alternative way to science of looking at the universe and evolutionism, but is plain wrong. Reiss didn’t appear to do this explicitly in his controversial talk at the British Association meeting. And his remark that “the concerns of students who do not accept the theory of evolution” should be taken “seriously and respectfully” sounds perilously close to saying that those concerns should be given serious consideration, and that one should respect the creationist point of view even while disagreeing with it. The fact is that we should feel obliged to respect points of view that are respectable, such as religious belief per se. Creationism is not respectable, scientifically, intellectually or indeed theologically (will they tell the kids that in Religious Education?). And if you are going to title your talk “Should creationism be a part of the science curriculum?”, it is reasonable that questions should be asked if you aren’t clearly seen at some point to say “No.”

So, a substantial case for the prosecution, it might seem. But for a start, one might reasonably expect that scientists, who pride themselves on accurate observation, will read your words and not just blunder in with preconceptions. It is hard to see a case, in Reiss’s address, for suggesting that his views differ from those that the Royal Society has restated in conjunction with Reiss’s resignation: “creationism has no scientific basis and should not be part of the science curriculum. However, if a young person raises creationism in a science class, teachers should be in a position to explain why evolution is a sound scientific theory and why creationism is not, in any way, scientific.”

This, to my mind, was the thrust of Reiss’s argument. He quoted from the Department for Children, Schools and Families Guidance on Creationism, published in 2007: “Any questions about creationism and intelligent design which arise in science lessons, for example as a result of media coverage, could provide the opportunity to explain or explore why they are not considered to be scientific theories and, in the right context, why evolution is considered to be a scientific theory.” The point here is that teachers should not be afraid to tackle the issue. They need not (indeed, I feel, should not) bring it up themselves, but if pupils do, they should not shy away by saying something like “We don’t discuss that in a science class.” And there is a good chance that such things will come up. I have heard stories of the genuine perplexity of schoolchildren who have received a creationist viewpoint from parents, whose views they respect, and a conflicting viewpoint from teachers who they also believe are intent on telling them the truth. Such pupils need and deserve guidance, not offhand dismissal. You can be respectful to individuals without having to ‘respect’ the views they hold, and this seems closest to what Reiss was saying.

And there’s nothing that disconcerts teachers more than their being told they must not discuss something. Indeed, that undermines their capacity to teach, just as the current proscription on physical contact with children undermines teachers’ ability to care for them in loco parentis. A fearful teacher is not a good one.

What perhaps irked some scientists more than anything else was Reiss’s remark that “Creationism can profitably be seen not as a simple misconception that careful science teaching can correct. Rather, a student who believes in creationism can be seen as inhabiting a non-scientific worldview, a very different way of seeing the world.” This is simplistic and incomplete as it stands (Gerald Holton has written about the way that a scientific viewpoint in some areas can coexist happily with irrationalism in others), but the basic point is valid. Despite (or perhaps because of) the recent decline in the popularity of the ‘deficit model’ of understanding science, some scientists still doggedly persist in the notion that everyone would be converted to a scientific way of thinking if we can just succeed in drumming enough facts into their heads. Reiss is pointing to the problem that the matter runs much deeper. Science education is essential, and the lack of it helps to pave the way for the kind of spread of ignorance that we can see in some parts of the developed world. But to imagine that this will undermine an entire culture and environment that inculcates some anti-scientific ideas is foolish and dangerous. I suspect that some scientists were angered by Reiss’s comments here because they imply that these scientists’ views of how to ‘convert’ people to a scientific worldview are na├»ve.

Most troubling of all, however, are the comments from some quarters which make it clear that the real source of outrage stems from the fact that Reiss is an ordained Church of England minister. The implication seems to be that, as a religious believer, he is probably sympathetic to creationism, as if one necessarily follows from the other. That creationism is an unorthodox, indeed a cranky form of Christianity (or of other kinds of fundamentalism – Islam and Judaism has its creationists too) seems here to be ignored or denied. It’s well known that Richard Dawkins sees fundamentalism as the centre of gravity of all religions, and that moderate, orthodox views are just the thin end of the wedge. But his remark that “a clergyman in charge of education for the country’s leading scientific organization” is like “a Monty Python sketch” itself has a whiff of fundamentalist intolerance. If we allow that it’s not obvious why a clergyman should have a significantly more profound belief than any other religious believer, this seems to imply that Dawkins would regard no Christian, Muslim, Hindu, Jew or so forth as fit for this job. Perhaps they should be excluded from the Royal Society altogether? Are we now to assume that no professed believer of any faith can be trusted to believe in and argue for a scientific view of the world? I do understand why some might regard these things as fundamentally incompatible, but I would slightly worry about the robustness of a mind that could not live with a little conflict and contradiction in its beliefs.

This situation has parallels to the way the Royal Society has been criticized for its involvement with the Templeton Foundation. I carry no torch for the Templeton, and indeed was on the wary lookout at the Varenna conference above for a hidden agenda. But I found none. It seems to me that the notion of exploring links between science and religion is harmless enough in itself, and it certainly has plenty of historical relevance, if nothing else. No doubt some flaky stuff comes of it, but the Templeton events that I have come across have been of high scientific quality. (I’m rather more concerned about suggestions that the Templeton has right-wing leanings, although that doesn’t seem obvious from their web site – and US rightwingers are usually quite happy to trumpet the fact.) But it seems sad that the RS’s connections with the Templeton have been lambasted not because anyone seems to have detected a dodgy agenda (I understand that the Templeton folks are explicitly unsympathetic to intelligent design, for example) but because they are a religious-based organization. Again, I thought that scientists were supposed to base their conclusions on actual evidence, not assumptions.

In regard to Reiss, I’m not going to start ranting about witch hunts (not least because that is the hallmark of the green-ink brigade). He was rather incautious, and needed to see how easily his words might be misinterpreted. But they have indeed been misinterpreted, and I don’t see that the Royal Society has done itself much of a service by ousting him, particularly as this seems to have been brought about by a knee-jerk response from scientists who are showing signs of ‘Reds (or in this case, Revs) under the bed’ paranoia.

The whole affair reminds me of the case of the Archbishop of Canterbury talking about sharia law, where the problem was not that he said anything so terrible but that he failed to be especially cautious and explicit when using trigger words that send people foaming at the mouth. But I thought scientists considered themselves more objective than that.

Thursday, September 04, 2008

Intelligence and design

Little did I realise when I became a target of criticism from Steve Fuller of Warwick University that I would be able to wear this as a badge of honour. I just thought it rather odd that someone in a department of sociology seemed so indifferent to the foundational principles of his field, preferring to regard it as a branch of psychology rather than an attempt to understand human group behaviour. I take some solace in the fact that his resistance to physics-based ideas seems to have been anticipated by George Lundberg, one of the pioneers of the field, who, in Foundations of Sociology (1939), admits with dismay that ‘The idea that the same general laws may be applicable to both ‘physical’ and societal behavior may seem fantastic and inconceivable to many people.’ I was tempted to suggest that Fuller hadn’t read Lundberg, or Robert Park, Georg Simmel, Herbert Simon and so on, but this felt like the cheap form of rhetoric that prompts authors to say of critics whose opinions they don’t like that ‘they obviously haven’t read my book’. (On the other hand, Fuller’s first assault, on Radio 4’s Today programme, came when he really hadn’t read my book, because it hadn’t been published at that point.)

Anyway, judging from the level of scholarship A. C. Grayling finds (or rather, fails to find) in Fuller’s new book Dissent over Descent, a defence of the notion of intelligent design, maybe my hesitation was generous. But of course one shouldn’t generalize. Grayling has dissected the book in the New Humanist, and we should be grateful to him for sparing us the effort, although he clearly found the task wearisome. But wait a minute – a social scientist writing about evolution? Isn’t that a little like a chemist (sic) writing about social science?