Sunday, April 29, 2012

Fantastic colours

I have an article on physical colours in nature, and their mimicry in artificial systems, in the latest issue of Scientific American. All you can get online without a subscription is a ‘preview’. But I shall put an extended version of the piece on my website soon.

Friday, April 27, 2012

Bad faith

I have a new Muse piece up on Nature news – very little done in editing, so I’ll just give the link. I fear that there will be more griping about my being soft on religion, but I don’t see it that way at all. The fact that so many religious people have so little interest in the intellectual tradition of religion should cause far more concern among religious leaders than it does. Of course, maybe some of them like it that way, their followers passive and unquestioning. Anyway, the point is that you can disagree with Aquinas et al., but it is absurd to suggest that they were just deluded or lacking in analytical acumen. That isn’t in any way the implication of the Science paper discussed here, but I imagine some interpretations will take that angle.

Saturday, April 21, 2012

Imagine that!

I was a bit tetchy about Steven Poole’s criticisms in his review of The Music Instinct in the Guardian, although subsequent discussions with him helped me to understand why he raised them. But now I see I escaped lightly. In today’s Guardian Review, Steve comprehensively demolishes Johan Lehrer’s new book Imagine, calling it a prime example of the sort of ‘neuroscientism’ which purports to explain everything about everyone with a few brightly coloured MRI scans. There is some seriously cruel stuff here: “‘For Shakespeare’, Lehrer affects to know, ‘the act of creation was inseparable from the act of connection.’” I confess to a degree of guilty pleasure in reading this unrelenting dissection, though I’d feel bad for Jonah if it wasn’t evident that it would take much more than this to tarnish his growing reputation as the next Malcolm Gladwell. I suspect there is an element here of Steve’s contrarian nature rebelling against the way Lehrer has been otherwise universally hailed as a Wunderkind. But it’s not just that. I fully recognize Steve’s complaint about the current simplistic infatuation with neuroscientific jargon and imagery, as if saying that an activity activates the anterior superior temporal gyrus is equivalent to having explained it. I’ve not read Jonah’s book, and so have to reserve judgement about whether it really is a prime offender in this regard. But it’s certainly high time this tendency were put in its place. A couple of reviewers of The Music Instinct who are neuroscientists were a bit sniffy about how it didn’t make more of the wonderful advances in understanding of musical activity that brain imaging has yielded. Now, there certainly have been significant discoveries made using those technologies – I think in particular of, say, Robert Zatorre’s work on the activation of reward centres when people experience ‘musical chills’, or Petr Janata’s amazing demonstration of harmonic maps imprinted on the grey matter (both of which I mention). But Dan Levitin, while generally quite nice to the book, seemed to want more about how “listening to music activates reward and pleasure circuits in brain regions such as the nucleus accumbens, ventral tegmental area and amygdala”. Ah, so that’s how music works! This was the kind of thing I intentionally omitted, rather than overlooked, because I think that at present it does little more than fool the easily impressed reader into thinking that we’ve really ‘got inside the brain’, while in truth we often have very little idea what these increases in blood flow signify about cognition. I have to add, though, that this is the second book review I’ve read recently (the first being Richard Evans’ review in the New Statesman of A. N. Wilson’s little book on Hitler, which triggered an entertaining spat) that makes me wonder whether the Hatchet Award has upped the ante. I’m sure I’m not alone in my anxiety. [By the way, how do you put paragraph breaks into this new-look blogger tool?]

Sunday, April 15, 2012

Architectural designs

I have a paper on pattern formation in the March/April issue of Architectural Design, a special issue devoted to ‘material computation’. My piece is fairly old stuff, I confess, although this is a topic that architects are becoming increasingly interested in. I will put a version on my website, once I have figured out why it seems to have (temporarily?) vanished from the webosphere. But there’s a lot of other interesting stuff in this issue, some of which I have written about in my next column (May) for Nature Materials.

Friday, April 13, 2012

Something for the weekend

I was on BBC Radio 4’s Start the Week programme this week, still accessible here (for just a day or two) on BBC iPlayer. And a copy of the book just arrived in the post – it’s a fatty, out at the beginning of May. I’m currently most of the way through Peter Carey’s The Chemistry of Tears, and enjoying it as much as I knew I would.

Thursday, April 12, 2012

Touchy-feel chemistry

Here’s my latest Crucible column for Chemistry World.

What does it feel like to be a molecule? Anthropomorphizing molecules is a familiar enough pedagogical trick – we’ve all seen those cutesy grinning balls-and-sticks in children’s texts on chemistry, and I’ve indulged in this exercise myself to explain the hydrogen-bonding arrangements of water. But perhaps we might stand to learn more from the opposite manoeuvre: not humanizing molecules, but molecularizing humans.

I was set thinking about this after seeing Jaron Lanier, the computer-science pioneer who coined the term ‘virtual reality’ and has done much to develop it as a technology, speak in New York about where VR may be headed. While describing exploratory research in which people are given non-human avatars (could you control a lobster body, say?), Lanier dropped one of those apercus that reveal why he is where he is. This isn’t just an extravagant computer game, he said – in such manifestations VR can be considered to be exploring the pre-adaptations of the human brain. That’s to say, it shows us what kinds of physicality, beyond the bounds of the human body, our brains are equipped to adapt themselves to. This sort of pre-adaptation is a crucial aspect of evolution: a genetic mutation might not simply alter an existing function, for better or worse, but can sometimes unleash the potentiality already latent in the organism’s genetic program. That is quite probably how Hox genes came to facilitate whole new ranges of body plans.

And then one might ask – as Lanier did – whether, as well as lobsters, our brains have the capacity to make themselves at home in a ‘molecule’s body’. Of course, molecules, unlike lobsters, don’t move of their own volition. But might our brains in some sense be able to perceive and intuit the forces that molecules experience: to assemble such sensory data into a coherent image of the molecular world?

Why ask such a seemingly arcane question? Lanier suspects that the embodied experience of VR, by engaging more sensory processes than, say, just vision or logical thinking alone, can offer us new routes to understanding and problem-solving. This is demonstrably true. Lanier, an accomplished musician, pointed out how improvising instrumentalists find their fingers accessing solutions to harmonic or melodic problems – how do I get from here to there – that would be far harder to identify by just sitting down and thinking it out.

Chemists probably need less persuading of this than other scientists. You don’t tend to work out a complex synthesis in your head: you draw out the molecular structures, and the visual information doesn’t just record your thoughts but informs them. For some problems you need to get even more tactile, building molecular models and moving them around, turning and twisting to see if they will fit together as you’d like. That has surely been evident ever since John Dalton devised his wooden ball-and-stick models.

There are already signs that molecular science wants to take this notion of ‘feeling molecules’ to a deeper level. Some years ago I tried out the ‘haptic’ (touch-based) interface of an atomic force microscope developed by Metin Sitti’s group at Carnegie Mellon University in Pittsburgh. This allows the user to feel a representation, in real time, of what the AFM tip is ‘felling’, such as the atomic topography of a surface and the forces that adsorbed molecules exert. It was certainly instructive – so much so that I remember the sensation vividly years later, just as I have never forgotten the feeling of putting my finger into mercury as a child. The haptic AFM felt quite different from the impression you’d get from an animation of what the instrument does: jerkier, somehow grittier.

Chemists have not so far made very extensive use of a more all-embracing VR. One exception is the Duke immersive Virtual Environment (DiVE) developed by the RISE science-education program at the Duke University Medical Center in Durham, North Carolina. This software can be used online, but is best experienced by the user fitted out with VR goggles and joystick manipulator in a small cube-shaped ‘theatre’ with images projected onto the walls and ceiling – a version of the CAVE created at the University of Illinois at Chicago.

Among the projects run for DiVE is ‘DiVe into Alcohol’, an experience that lets you follow the progress of ethanol molecules as they travel through an avatar’s gastrointestinal tract and become oxidized by the enzyme alcohol dehydrogenase in the liver. If you’re in Durham NC you can literally see for yourself: the RISE team offers an open house to all comers on Thursdays.

But Lanier seems to have something more ambitious in mind: the sensation of actually being a molecule. That sounds a little scary: what is it like to be oxidized by having your hydrogens pulled off? But who knows what insights we might gather in the process? Lanier is even exploring how to make such realizations governed by quantum rather than semiclassical rules. Might it be that the famously counterintuitive principles of quantum physics would become less so if we can actually experience them?

Thursday, April 05, 2012

Dreaming of ferroelectric sheep

Here’s the pre-edited version of another of my pieces for BBC Future (again, this link will only work outside the UK).

There are some scientific discoveries that you never get to hear about simply because they’re too perplexing to bring news writers running. That’s likely to be true of findings reported by mechanical engineer Jiangyu Li of the University of Washington in Seattle, Yanhang Zhang of Boston University, and their colleagues. They’ve found that the tough, flexible tissue that makes up the aorta of pigs has the surprising property of ferroelectricity.

This arcane but technologically useful behaviour is found in certain crystals and liquid crystals. It’s a sort of electrical equivalent of magnetism. Indeed, that analogy explains why the phenomenon is called ferroelectricity, despite the absence of iron (ferrum) in materials that show it, because of the similarities with what is technically called ferromagnetism, as displayed by magnetic iron.

A ferroelectric substance is electrically polarized: one side has a positive electrical charge and the other a negative charge. This polarization can be switched to the opposite direction by placing the substance in an electric field that reorients the charges. It has its origin in an uneven distribution of electrical charges in the arrangement of constituent atoms or molecules. Just as a magnetic field can make a magnetized compass needle change direction, so an electric field can pull all the little electrical charges into a different alignment.

The switchability is why ferroelectric crystals are being studied for use in electronic memory devices, where binary data would be encoded in the electrical polarization of the memory elements. They are also used in heat sensors (the switching can be very sensitive to temperature), vibration sensors and switchable liquid-crystal displays.

Li usually works on synthetic materials like these for applications such as energy harvesting and storage. He and his colleagues discovered ferroelectricity in pig aorta by placing a thin slice of it in a special microscope containing a sensitive needle tip that could detect the electrical polarization. They found that they could switch this polarization with an electric field.

Why on earth should any animal tissue be ferroelectric? Well, the living world does make use of some unexpected material properties. Bone, for example, is piezoelectric: it becomes electrically polarized, and so sets up an electric field, when squeezed. Piezoelectricity is also a useful kind of behaviour in technology: it is exploited, for instance, in pressure and vibration sensors like those in your computer keyboard. It seems that bony creatures use this principle too: the electrical response to squeezing of bone helps tissues gauge the forces they experience. In seashells, meanwhile, piezoelectricity helps prevent fracture by dissipating the energy of a shock impact as electricity.

OK – but ferroelectricity? Who needs that? Commenting on the findings, engineers Bin Chen and Huajian Gao have speculated that the property might supply another way for the tissue to register forces, and thus perhaps to monitor blood pressure. Or perhaps to sense blood temperature, or again to dissipate mechanical energy and prevent damage. Or even to act as a sort of ‘tissue memory’ in conjunction with (electrically active) nerves. Li, meanwhile, speculates that switching of the ferroelectricity might alter the way cholesterol, sugars or fats stick to and harden blood vessels.

Notice how these researchers have no sooner identified a new characteristic of a living organism than they start to wonder what it is for. The assumption is that there must be some purpose: that evolution has selected the property because it confers some survival benefit. In other words, the property is assumed to be adaptive. This is a good position to start from, because most material properties of tissues are indeed adaptive, from the flexibility of skin to the transparency of the eye’s cornea. But it’s possible that ferroelectricity could be just a side-effect of some other adaptive function of the tissue – a result of the way the molecules just happen to be arranged, which, if does not interfere with other functions, will go unnoticed by evolution. Not every aspect of biology has a ‘purpose’.

All the same, tissue ferroelectricity could be handy. If Li is right to suspect that ferroelectricity can influence the way blood vessels take up fats, sugars or lipids, then switching it with an applied electric field might help to combat conditions such as thrombosis and atherosclerosis.

: Y. Liu et al., Physical Review Letters 108, 078103 (2012).