This article is a preview from the Spring 2019 edition of New Humanist
Physics – Ceri Brenner
On my drive home recently I hit a smooth run of green lights and zero congestion between leaving the motorway and turning into my road. The combination of satisfaction and rarity has affected me so much that here I am, retelling it. But there is a point, I promise. Imagine if every car journey was this way – no stopping, accelerating, braking, no energy being wasted via heat on the brakepads, no spikes in fuel consumption to get the wheels turning. For this, you’d need every journey to have zero resistance to the car’s motion: nothing to make it hard for the cars to flow. This ideal scenario – but with a flow of electricity instead of cars and materials instead of roads – is what we call superconductivity. A superconducting material has very little, almost zero, resistance to electricity; it’s the most energy-efficient way for electricity to flow. It could drastically improve the efficiency of electricity generation and transmission, and revolutionise high power-consuming technology like supercomputers and big data-handling equipment.
Superconductivity is available to us now – having first been discovered in 1911 in solid mercury cooled down to minus 269°C – but with the big limitation that many materials only demonstrate this property when cooled to around minus 180°C. This is not a sustainable option. The hunt is on for a room-temperature superconducting material. There are a lot of people around the world putting their minds to cracking this challenge. And now a group from George Washington University in the US have published results in Physical Review Letters showing evidence that a new material is demonstrating superconductivity at “normal” temperatures. They synthesised the material – lanthanum superhydride – by compressing lanthanum and hydrogen under extreme pressure in a diamond anvil machine (to half the pressure at the centre of the Earth!) and then subjected it to resistance tests. Significant drops in resistance appeared when the material was cooled below minus 13°C – positively balmy in comparison.
Ceri Brenner is a physicist who works for the Science and Technology Facilities Council
Chemistry – Mark Lorch
In 1869 a Russian chemist named Dmitri Mendeleev sat down with a homemade deck of 63 cards, one for each of the known chemical elements. The story goes that he arranged them in columns and rows according to their chemical and physical properties. The arrangement he settled upon became the periodic table. To celebrate 150 years since then, the UN has proclaimed 2019 the International Year of the Periodic Table. But the periodic table didn’t start with Mendeleev. Many others attempted to arrange the elements in a coherent order. Antoine Lavoisier – sometimes known as the father of modern chemistry – published a table of elements 70 years before Mendeleev. And 40 years later Johann Wolfgang Döbereiner noticed that elements can be grouped by their chemical properties – grouping together lithium, sodium and potassium as soft, reactive metals.
What set Mendeleev apart was not just how he arranged things but what he left out. He recognised that elements were missing from the patterns of reactivity, and left spaces. Moreover, he used the patterns he observed to predict the properties of the missing elements. For example, he placed a question mark next to aluminium to represent an unknown metal. Mendeleev foretold it would have an atomic mass of 68, a density of six grams per cubic centimetre and a very low melting point. Sure enough, six years later Paul Émile Lecoq de Boisbaudran isolated gallium and it slotted right into the gap with an atomic mass of 69.7, a density of 5.9g/cm³ and a melting point so low that it becomes liquid in your hand. Mendeleev did the same for scandium, germanium and technetium (discovered in 1937, 30 years after his death).
Since then the periodic table has expanded and evolved considerably. The ranks of the elements have swelled to include 94 that occur naturally plus another 24 synthetic elements. The table that stares down from the walls of most chemistry labs and classrooms is also just one of literally hundreds of alternative arrangements, which include spirals, extensions, flowers and intricate 3D representations. All of which owe a tribute to Mendeleev and his 150-year-old infographic.
Mark Lorch is a chemist at the University of Hull
Biology – Louise Gentle
Can magpies count? New research published in Animal Behaviour suggests they can. When making decisions, individual magpies can use either personal information gathered by themselves or social information gained from watching or listening to others. Eavesdropping is particularly useful for predator detection. Listening out for alarm calls of others is low risk, while gathering personal information can result in death. But social information can be dishonest, as some individuals will intentionally produce false alarm calls in order to scatter individuals then steal resources. Therefore, although eavesdropping on more individuals increases the chance of detecting a predator, it also increases the chance of misinformation. So being able to assess the number of individuals providing information is a useful tool.
Researchers used play-back experiments to study the impact of alarm calls on the behaviour of Australian magpies. The magpies were subjected to calls from either one or two non-magpies, and showed a much stronger response to the alarm calls of two birds – they were more likely to flee the area rather than just scan for predators. In a second experiment, the magpies were subjected to calls from two individuals of either the same or different species. In theory, calls from multiple species could provide additional information. For example, simultaneous alarm-calling from two species, where one is susceptible to large predators and the other to small predators, could indicate the presence of a medium-sized predator. But this study found no difference in the response of the magpies to mixed and same species alarm calls.
So, it appears that magpies can be more certain when given information from more individuals, as this reduces the chance of false alarms. Also, predators that are more dangerous should cause more individuals to alarm call. However, the combination of species, or rather the combination used in this study, gives no additional information about the predation threat, making it the quantity, and not the quality, of information that is important to magpies.
Louise Gentle is a senior lecturer in behavioural ecology at Nottingham Trent University
