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Everyday science

The Euler spiral of rat whiskers, a colourful Inca statue, a “quantum bottleneck” in hiring

17 Jan 2020 Margaret Harris
A photo of a rat, showing its whiskers of varying lengths
A rat's whiskers. (Courtesy: iStock/wildcat78)

Like most humans, I’m not a big fan of rats. I do, however, have a grudging admiration for their cunning and endless adaptability, and it turns out that some of their keen rat-sense may be down to mathematics. In a study of 523 whiskers from 15 individual rats, researchers in London and Manchester, UK found that the variety of whiskers on a rat’s cheek can be described by a simple mathematical equation.

The whiskers all have different lengths and shapes, and their distribution is such that each whisker is represented as an interval on the Euler spiral. The researchers conjecture that this distribution is “a manifestation of linear laws underpinning rat vibrissae [whisker] growth”, similar to the logarithmic spirals that appear in seashells. Also like seashells, the pattern of a rat’s whiskers has function as well as form. “The size and natural shape of each whisker, including its taper and intrinsic curvature, strongly influence the manner in which it deforms, and therefore, the tactile signals in the follicle,” they conclude.

We at Physics World always like to see physics techniques applied to solve problems in other disciplines. This week brought news (via Physics World contributing editor Belle Dumé) that researchers in France have used X-ray fluorescence spectrometry to analyse the colours painted on a statue of the Inca god and oracle Pachacamac. This measurement, combined with the first carbon-14 dating of the statue, has shed light on how the Inca civilization and its predecessors used and valued coloured pigments.

Among other findings, the researchers learned that the statue’s red pigment is not derived from blood, as was previously thought, but from a mercury-bearing ore called cinnabar. This is interesting because cinnabar is uncommon in the Andes, and the nearest source to the Pachacamac site is a few hundred kilometres away. Meanwhile, carbon-dating revealed that the statue was fashioned around 731 AD, nearly 800 years before the Spanish conquest of the Inca Empire, and 700 years before the empire reached its apogee. This confirms that the Pachacamac site was already important for local people before the Incas adopted it as a centre of pilgrimage.

Finally, I was intrigued by an article in the Guardian newspaper about the so-called “quantum bottleneck”. It seems that the world at large, and the UK in particular, is not producing enough people with the skills required for the nascent quantum-computing industry. The article quotes Doug Finke, who manages a website called Quantum Computing Report, as saying that the expansion of commercial quantum computing “has encouraged a number of academics to leave academia and join a company”. Finke goes on to warn that this academic exodus may create a shortage of professors to teach the next generation of students.

I don’t doubt that this is a real problem, but even so, whenever anyone bemoans the fact that physicists are leaving academia for industry, what I hear is, “Talented people are getting hired into well-paid permanent jobs, rather than spending the next five or more years of their lives in itinerant, ill-paid and insecure postdocs.” In a week that also saw a damning report from the Wellcome Trust on academic research culture, I can’t help but wonder whether some of these departing physicists are being pushed away by poor working conditions in universities, as much as attracted by high salaries in companies.

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