Wednesday, 29 February 2012

bbc english #5: explaining science

Like many websites that contain frequently updated information, the BBC News website includes a list of the ten ‘most read’ stories. When I logged on to the site a couple of days ago, I noted that the tag line for the top story was ‘Electric image of single molecule’. It is encouraging to see that reports about cutting-edge science are widely read, although I do wonder how many readers know enough about the science behind a given story to be able to critique that story.

I would concede immediately that science journalism is more difficult than most other types of journalism, because simplifying a story for a general audience risks changing it in a fundamental way, while nothing essential is lost in reporting the devious dealings of modern financiers if a credit default swap is described as ‘an insurance policy’. However, it is in the nature of science that the language used for its description should be precise. The tag line noted above is a poor start (what is an ‘electric image’?), although the article title—‘Single molecule’s electric charges seen in first image’—conveys more information. But one crucial word is missing: ‘distribution’ (more on this in a moment).

The text of the story itself is in need of some critical corrections. For example, take the following sentence:
The work comes from a group at IBM Research Zurich that specialises in examining the world at the infinitesimal scale of atoms and molecules.
I’m bound to ask whether the anonymous journalist responsible for this piece has any idea what ‘infinitesimal’ actually means. It certainly does not mean ‘extremely small’, which is a fair description of atoms and molecules. In fact, ‘infinitesimal’ has a precise mathematical meaning, which can be explained as follows: take a number (1 is as good as any) and divide by two. Repeat this operation an infinite number of times. The result will be an infinitesimal value, not quite zero but unquantifiably close to zero.

The molecule in question, naphthalocyanine, has an approximately X-shaped structure in which the arms of the X are naphthalene molecules attached to a central hub or ring of nitrogen atoms. The scientific breakthrough being described is the ability to produce an image that shows the electronic charge distribution across the molecule:
As the charged tip encounters charges within the naphthalocyanine, the cantilever begins wagging in a way that shows up precisely where the electrons are.
Unfortunately, the image does not show ‘precisely where the electrons are’, because such precision is not possible. What the image actually shows is a probability function, a sum of all the possible positions of all the electrons in the molecule.

Finally, the author adds a few words to reflect on possible future applications of this new imaging technique:
In combination with more established techniques, the approach will shed light on the nanoscale world that is promising not only for fundamental science, but also for future applications in which electric behaviour at such scales will be exploited.
Although the second comma serves no purpose, the offending word here is ‘nanoscale’. For reasons that are not obvious, the prefix ‘nano–’ appears to have become established as a way of indicating that something is very small, in the same way that ‘mega–’ is now widely used for anything that is larger than the ordinary. However, like ‘infinitesimal’ above, both ‘nano–’ and ‘mega–’ have precise meanings, in this case as defined in the modern version of the metric system, from which both prefixes have been borrowed. Thus a nanometre is precisely 1/1,000,000,000th of a metre, which I think everyone will agree is an extremely short distance. However, molecules typically have diameters that are even smaller, between 60 and 600 picometres (a picometre is 1/1,000,000,000,000th of a metre), so we should really be talking about the picoscale here. And if we are discussing atomic nuclei, then 2–20 femtometres (add another three zeroes to the divisor) is a typical diameter, so nuclear reactions (fission, fusion) can be said to take place at the femtoscale.

Despite the inaccuracy, I suspect that we are now stuck with both ‘nano–’ and ‘mega–’, because both have escaped from their original scientific usage into general circulation. I wonder whether this reflects a decline in the standard of education in science or English, or both, or whether I’m merely being over-sensitive to modern trends in language usage.

other posts in this series
BBC English.
Grand Slam.
More or Less.
Making an Impression.


  1. It's interesting. It's striking that the more precise and accurate description (which you fill in) actually makes the ideas clearer, more intelligible.

    I do understand the difficult position that the writer to a lay audience finds himself in -- I don't know of a perfect solution when balancing accuracy on one hand with use of language familiar to non-experts on the other.

    Of course nanoscale can be easily substituted by 'extremely small scale' in the case when nanoscale is inaccurate. But to convey the idea that the image shows a 'charge distribution' really would require additional information for the reader that has no mental image associated with a mathematical 'distribution'. However, if the writer were to add the extra paragraph to explain the idea of a charge distribution, I do think that referring to visual representation of a 'charge distribution' would make the article clearer even for an intelligent lay reader.

    1. Jon, I think you’re right in saying that ‘extremely small scale’ is an adequate substitute for ‘nanoscale’, and also that explaining charge distribution as a probability function is at the heart of the difficulty. Part of the problem, at least for British readers, is that the image of an atom as having concentric shells of electron orbits, like a mini solar system, is a gross over-simplification. It is also the case that students are not introduced to the Heisenberg Uncertainty Principle until they reach university, yet knowledge of this principle is essential if one is to understand why it is that the precise location of an electron cannot be determined, and its orbit is merely the sum of all its possible locations.

      If all this sounds rather vague, it’s because I’m not an expert in quantum mechanics either, although I do believe that I understand the principles. However, that belief could be mistaken.

      By the way, did you read the original article? The image was reproduced without an explanatory caption.


Please leave a comment if you have time, even if you disagree with the opinions expressed in this post, although you must expect a robust defence of those opinions if you choose to challenge them. Anonymous comments will not be accepted.