Wednesday, July 25, 2007

Cold is hot

Three cheers for BBC4’s Absolute Zero, a two-part series on ‘cold’ that began last night. I thought this was one of the best science programmes I’ve seen for a long time. It made me very happy to see the programme explaining – gasp – thermodynamics, including the Carnot cycle. Even the now-obligatory dramatic reconstructions were fairly unobtrusive and a little bit inventive. This was startlingly old-fashioned TV, in a good way: a story told chronologically, with good contributors (Simon Shaffer is always good value, and it was nice to see that they’d found Hasok Chang), minimal flashy graphics, and a sober commentary.

Nothing’s perfect – in particular, I suspect that many people will have found the explanations of Carnot and refrigeration hard to follow without having been given some essential concepts such as the gas laws and latent heat. But full marks for trying. And I learnt some stuff, such as Michael Faraday’s discovery of the principle of the compression-condensation cycle of fridges, and Joule’s work on the relationship of heat and energy. I look forward to tonight’s episode.

Saturday, July 21, 2007

Liquids bounce again
[I can’t resist putting up this little item, written for news@nature, because it is a classic kitchen experiment you can do yourself – the recipe is below.]

Jumping jets move from the bathroom to the kitchen

After bouncing shampoo, physicists now bring you bouncing cooking oil. A team in Texas has found that the trampolining of a liquid jet falling onto a bath of the same liquid is more common than expected.

Last year, a group in the Netherlands studied this bouncing effect for a jet of shampoo. The bounce, which was first reported over 40 years ago, happens because of the peculiar nature of shampoo, which gets thinner (less viscous) as it flows. A jet of it hitting a liquid surface is therefore lubricated by a thin layer at the interface, enabling it to bounce off rather than merge.

But the liquids now studied by Matthew Thrasher and colleagues at the University of Texas at Austin don’t have this property – they are viscous, but have ‘normal’ flow behaviour, like water.

The researchers directed a jet of oil vertically onto the surface of a tank of the same oil. They found that the jet could undergo both a ‘leaping’ rebound and a bizarre ‘flat’ bounce in which it sprang horizontally across the liquid surface.

The bounce here is due to a thin layer of air that separates the two liquid surfaces, the researchers say.

They point out that the effect can easily be recreated in a kitchen experiment with cooking oil. Just fill a glass pie dish with about 4 cm of oil and pour onto it a thin stream from a cup about 3-6 cm above the surface. While pouring, move the stream in a circle about once every 2 seconds (or rotate the dish on a Lazy Susan). The bounce can be encouraged by passing a small rod like a chopstick through the stream every now and then.

Wednesday, July 18, 2007

Chartres on film

Late last year I nearly froze my tender parts off standing on the turret of a ruined Tudor mansion in Sussex taking about Chartres cathedral. (Tudor? Well, fortunately it was shrouded in icy fog.) I was being filmed for programme being made for the National Geographic channel on the building of the cathedral, the subject of my forthcoming book Universe of Stone (published next May by Random House and Harper Collins, since you ask).

I’ve just been sent a DVD of the result, which you can watch here. It is not terrible. That doesn’t sound much of a recommendation, but frankly it has become hard to expect very much of history programmes now. There is, of course, a lot of footage of people running around dressed a peasants or bishops, looking respectively angry or devout. For what was presumably a very modest budget, some of the footage looks rather impressive: in particular, nice graphics of the building (which I’d love to get my hands on for the book, instead of slaving away pencil in hand). But I’d have liked rather more of the real cathedral, without all the soft focus and computer enhancement – it doesn’t need tarting up like that.

Needless to say, every last bit of drama is wrung from the story, often at the cost of stepping way beyond what we can confidently say. I found myself several times saying “Are you sure?”, or “How do you know that?” We get the standard line on issues such as the Cult of the Carts and the donation of the Windows of the Trades, which have now been more or less debunked. We get the usual mystical speculation about the labyrinth (walk it if you like, but don’t assume that medieval pilgrims did the same). Some things, such as the novelty of the flying buttresses and of the bleu de Chartres in the windows, are just plain wrong, in an attempt to make Chartres seem more innovative than it was. I sensed some influence of John James’ dodgy ‘contractors of Chartres’ idea. So I’m afraid this is very much a ‘guide book’ picture of what went on, which treats the history in a rather cavalier fashion. But there are some nice remarks by the contributors (I liked the sceptical angle on the miraculous survival of the Sacred Tunic), and I suppose all one can really hope for is that a programme like this makes you consider going to Chartres, which you certainly should.

As for the British guy who tells us solemnly that we know nothing about the master builder of Chartres except that “he must have been very experienced” – well, duh. It must have been the cold squeezing the blood from my brain.

Tuesday, July 10, 2007

It could only happen in the movies
[This is the pre-edited version of my latest article for]

Real science can’t compete at the movies with bad science. But perhaps that’s how it is meant to be.

“I’m arresting you for breaking the laws of physics”, says the policeman to the levitating man in a cartoon that speaks volumes, not least about the curiously legalistic terminology that science has adopted for its fundamental principles. In this spirit, two physicists at the University of Central Florida appear intent on making a citizen’s arrest of the entire Hollywood movie industry. In a preprint, they examine some egregious errors of physics in recent blockbusters [1].

The contempt that Hollywood shows for science is notorious. From loud explosions in deep space to genetically engineered spiders that transmute man into semi-arachnid, the movies are littered with scientific nonsense. But how much does this matter?

A lot, say Costas Efthimiou and Ralph Llewellyn. They argue that science bloopers in movies “contribute to science illiteracy.” Hollywood, they say, “is reinforcing (or even creating) incorrect scientific attitudes that can have negative results for society”.

If that is true, I suspect it’s not in the way they think it is. For decades, Hollywood has endorsed the archetype of the mad scientist [2] – an image that vastly predates the advent of cinema [3]. But recent portrayals of scientists in big movies are more nuanced: they are sometimes saviours (Armageddon), sometimes tortured geniuses (A Beautiful Mind), and most extraordinary of all, sometimes sexy (Jeff Goldblum in Jurassic Park).

Efthimiou and Llewellyn are less concerned with the image of science, however, than with its veracity. They explain (with equations) why the bus in Speed couldn’t possibly jump over a gap in a horizontal bridge segment of highway, why the Green Goblin in Spiderman couldn’t hold up the cable of the tramway between Manhattan and Roosevelt island, and why Magneto in X-Men: The Last Stand would have to glow like a lightbulb and lose 1350 pounds of body weight in order to shift the Golden Gate bridge by 5 km.

At face value, their analysis tilts at windmills. Let’s suppose, say, that the makers of X Men appreciated that by generating the power needed to achieve his feat, Magneto would need to emit about 18 million watts per square metre. Are we to suppose that viewers, seeing him become incandescent, would think “ah – blackbody radiation”. Or might they instead think “ah – superpowers make you glow”?

But these explorations of Hollywood’s scientific absurdities do raise some interesting questions. For example, how readily can we intuit cases of physics abuse? When we see superheroes perform impossible feats of gymnastics, do we innately sense that laws are being broken?

That question is often turned around in discussions of sporting prowess. No one supposes that baseball fielders or football players are predicting trajectories using Newtonian mechanics; rather, they seem to have a superior intuitive sense of its dynamical consequences.

The interesting question for movie makers (although I doubt that they formulate it this way) is not “how can I respect physical laws?”, but rather, “how can I break physical laws without shattering an illusion of plausibility?” The answer to that question might imply interesting things about how much our senses have been evolutionarily honed to appreciate the laws of physics. British biologist Lewis Wolpert has argued persuasively that, on the contrary, much of science depends on subverting intuitive reasoning about the world [4].

But should we endorse the violations of physics routinely perpetrated by Hollywood? Efthimiou and Llewellyn clearly think not. I would argue that you might as well complain about such ‘errors’ in the Greek myths or in fairy tales, or for that matter in Warner Brothers cartoons. Blockbuster movies are in many ways the modern equivalents of classical myths, their scenarios so unashamedly fantastic that we have no illusions about what we’re getting. I suspect movie-makers and movie-goers both understand this unspoken contract.

In fact, the unworldly exploits of superheroes have been used to good effect in physics education [5]. And Efthimiou and Llewellyn have themselves already acknowledged that Hollywood’s bad physics provides a superb vehicle for cultivating students’ skills at making back-of-the-envelope estimates, or what are now known as Fermi problems (because of Enrico Fermi’s talent for finding ways to make estimates about seemingly obscure or intractable quantitative questions) [6,7].

One might argue that scenarios such as the bus jump in Speed are more troubling, as they tend to be presented in an apparently realistic mode. I’m not so sure; this scene is merely replaying an old movie convention (the death-defying leap – see John Wayne in Brannigan), and indeed the more serious shortcoming is its lack of imagination.

The main message people take away from movies, however, isn’t concerned with how the physical world works; it is about narratives. Bad physics is far less dismaying than, say, the militaristic bravado of Independence Day or the xenophobia of True Lies.

Nonetheless, if you crave an antidote to Hollywood’s bad science, you can find it on YouTube, where sixteen scientists working on a project to make gas sensors from carbon nanotubes are posting video diaries of their progress.

In this project, called Nano2Hybrids and supported by the UK-based Vega Science Trust, the Belgium-based scientists are receiving video training from an experienced documentary maker, and they record their results on a website where viewers are encouraged to leave feedback.

The aim is to show people how scientific research really works. So I expect to see weeks of frustration as experiments fail, lots of staring at computer screens, tedious late-night observational runs, and some 18-rated language when the referees’ reports arrive. It’s already reassuring to see so few white lab coats.

This isn’t the first attempt to put science on YouTube. But it may be the first to try to fully document a research project this way. That could be highly informative, not least because it should explode some hoary myths about what scientists do and how they behave.

But somehow, I doubt that a scientist describing her results in front of a laptop will compete with Spiderman swinging around Manhattan. And that’s as it should be, because fantasy is not supposed to be constrained by the mundane laws that confound scientists in the lab.

1. Efthimiou, C. J. & Llewellyn, R. A. Preprint (2007).
2. Frayling, C. Mad, Bad, and Dangerous: The Scientists and the Cinema. (Reaktion Books, 2005).
3. Haynes, R. From Faust to Strangelove: Representations of the Scientist in Western Literature (Johns Hopkins University Press, 1994).
4. Wolpert, L. The Unnatural Nature of Science (Faber, 1992).
5. Gresh, L. H. & Weinberg, R. The Science of Superheroes (Wiley, 2002).
6. Efthimiou, C. & Llewellyn, R. Preprint (2003).
7. Efthimiou, C. J. & Llewellyn, R. A. Preprint (2007).