Sommaire pour April 2018 de BBC Science Focus Magazine

The world has lost a giant. Prof Stephen Hawking, the Galaxy’s best-known scientist and most unlikely cultural icon, died on Wednesday 14 March at his home in Cambridge. I’ve spent the days since speaking to those who knew Hawking and one clear theme emerges. Hawking was a stubborn man. Of course, he was funny and smart, that was clear for the world to see. But perhaps, to those of us watching from afar, his radiance hid the vital ingredient to his genius: true grit. Hawking was determined to never let his condition slow him down. Sometimes literally: Hawking broke his leg on his 60th birthday after driving too fast off a kerb. He travelled the world, and even had a taste of zero-gravity. He hoped one day to get a…

It looks like good things really do come in small packages: a baby Enantiornithes fossil the size of a cocktail sausage is helping a team at the University of Manchester to piece together the evolution of modern-day birds. Enantiornithes were a group of prehistoric birds that lived during the Mesozoic era – the age of the dinosaurs. They were able to fly and looked much like modern birds, save for the fact that they had teeth, as well as clawed fingers on each wing. The fossil in question was unearthed from the bottom of a lake in Spain several years ago, but recent analysis using high-powered particle accelerators known as ‘synchrotrons’ has enabled researchers to picture the tiny specimen at a submicron level, observing the bones’ microstructures in extremely fine…

The sounds made by marmoset monkeys are built from individual syllables of fixed length, much like human speech, researchers at the University of Tübingen, Germany have found. Such a rhythm may have been a key step in the evolution of true speech, they say. Whether saying a short word such as ‘hi’ or a longer one such as ‘floccinaucinihilipilification,’ everything humans say is made up of smaller units of sound lasting an average of one-seventh of a second, regardless of the language spoken. This rhythm is inherent in our production of syllables, and is due to the structure of our voice boxes and the neural processes that control speech. The Tübingen team has now found that the vocalisations of marmosets, a type of small primate found in South America, also…

DR CHRISTOPHE GALFARD Writer, science communicator and former PhD student of Prof Stephen Hawking. “I was Hawking’s PhD student from 2000 to 2006 at Cambridge University. I wasn’t really daunted by his celebrity – in the academic world, that’s kind of irrelevant – but what was daunting was that he was extremely hard to work with, in the sense that he wasn’t interested in scientific small talk. He only wanted to tackle the big questions: the hardest problems in theoretical physics. He had a rare intuition that I think is possessed by only a handful of scientists every century: he could see beyond the maths to the bigger picture. I worked with him on a type of string theory called M-theory that tries to combine everything we know about the…

 What do you think today’s robots can usefully contribute to the police service? “A malicious person could hack into a police robot and cause all kinds of havoc, particularly if they’re remotely controlling it” The one positive thing that I can see is a kind of reassuring presence. That’s if they’re trusted. It depends on how people react to the robots, but robots moving around a shopping mall, for instance, could prove reassuring – even if not as much as real, live human police. Having said that, I do appreciate there are cultural differences, and in some countries, particularly in the Far East, robots are likely regarded with a greater level of trust than in the UK. There’s talk of robots being given greater powers. Could they make arrests? The…

“COULD WE BE LOOKING AT THE DAWN OF A NEW KIND OF WAR – ONE FUELLED BY A BATTLE FOR DOMINANCE OVER OUR CLIMATE?” Climate change is a problem in desperate need of a solution. According to the authoritative Carbon Action Tracker, even if all nations honour their pledges to cut their greenhouse gas emissions, the globe will still warm by around 3.2°C by 2100 – with catastrophic consequences for humanity and the animal kingdom. If cutting greenhouse gas emissions isn’t enough, is it time for a plan B? Recent times have seen a surge of interest in geoengineering: China has recently embarked on a substantial research plan, while in the US, Prof David Keith of Harvard University is planning to launch a high-altitude balloon this year to test the…

Why do tattoos fade? ANTONIO JONES, LONDON Tattoo needles deposit ink beneath the epidermis. This is deep enough that the ink won’t be immediately shed with the skin cells of the upper layers, but macrophage cells from your immune system will gradually absorb the ink and disperse it. And the UV frequencies in sunlight are energetic enough to break down the ink molecules over time, so tattoos that are always exposed – such as on the fingers or face – fade quicker than those covered by clothing. LV Why have big cats evolved but not big dogs? JONNY THOMPSON, GLASGOW Big cats mostly hunt alone and rely on a short burst of speed to catch their prey, and swipes from their claws to bring it down. Wild dogs hunt differently,…

What do you do? I study the way that people move around in stadiums, museums, hospitals and the like. I collect data, then use it to see how the building will perform. Will it hold enough people? Will they be able to use the space effectively? Will they be able to get out in an emergency? What projects have you worked on? Wembley Stadium, St James’s Park and Principality Stadium. I once spent a week timing how long it took people to use the toilets in Ottawa airport. Rock ‘n’ roll! We’ve done stuff for Glastonbury Festival too. Can you explain why, at festivals, there is always a queue for the toilets? I can tell you why there shouldn’t be. Before the event, we look at the site design, model…

HAYLEY BENNETT Real-life Robocops are here, but should we be worried about them? Science writer Hayley gives us the full lowdown on these computerised cops. p56 CLIVE HAMILTON As nations look to geoengineering as a possible way out of climate change, ethicist Clive warns that it could lead to a new kind of war. p70 ALLA KATSNELSON Alla has been reporting on health and science for over a decade. This issue, she finds out how wildlife could recover in the aftermath of a nuclear event. p50…

While electric vehicles are a good idea in principle, they still require the generation of electricity. This is often achieved by the burning of fossil fuels, notably natural gas. This is more efficient in terms of carbon dioxide production and removes pollution from our cities. However, electric cars require lithium batteries, and there simply is not enough lithium on Earth for every petrol vehicle to be replaced by an electric one. Obviously, new sources of lithium, more efficient batteries and new battery technology will probably come along. I would like to suggest that, since every vehicle is already powered by an internal combustion engine, what we really need is an alternative liquid fuel to petroleum products. Methanol is the most likely candidate and some good work is being done to…

What did they do? Researchers at Australia’s Queensland Museum made a real-life chicken run by making a race track for domestic hens and measuring the movements in their hips as they sped around it. Why did they do that? The team were interested in figuring out how two-legged dinosaurs moved. As there are only static records of dinosaur gaits, such as footprints and fossils, the researchers turned to the extinct reptiles’ closest living relatives – birds. What did they find? Birds’ gait, and probably that of dinosaurs, varies according to the size of their bodies. Larger animals run in a more upright position, with a longer stretch in their legs. T.rexwas likely to have run much like a giant ostrich, the researchers say.…

TATTOOING IS AT LEAST 5,000 YEARS OLD Pictures of a wild bull and a Barbary sheep have been found tattooed on the upper right arm of Gebelein Man – a naturally mummified body, dating from between 3351 and 3071 BC, that’s currently on display at the British Museum. The marks look like dark smudges in natural light but were revealed to be tattoos using infrared imaging. CYCLING CAN SLOW DOWN AGEING Regular cycling can help to maintain healthy muscle mass, immune system function and cholesterol and testosterone levels well into old age, researchers at the University of Birmingham have found. Time to break out the Lycra? FAKE NEWS SPREADS FASTER THAN THE TRUTH After analysing the progress of 126,000 news stories on Twitter, a team at MIT has found that…

1942 Born 8 January in Oxford to Frank and Isobel Hawking. He is the eldest of four siblings. In 1950 the family moves to St Albans, where Hawking attends the private St Albans School. 1958 Assisted by their maths teacher Dikran Tahta, Hawking and a group of schoolfriends build a working computer from a telephone switchboard and some old clock parts. 1962 Graduates from University College, Oxford with a first-class honours degree in natural sciences. He begins studying for a doctorate in cosmology at Trinity Hall, Cambridge. 1963 Diagnosed with a type of motor neurone disease called amyotrophic lateral sclerosis (ALS). He is told he has just two years to live. 1970 Publishes an essay with cosmologist Roger Penrose (pictured right) that offers ‘proof’ of the Big Bang, as opposed…

Early on the morning of 30 December 2007, a drunk 41-year-old man left a party in the city of Stokmarknes, in northern Norway. Soon after, he slipped and fell into a steep-sided ditch. Plunged neck-deep in the freezing water, he was unable to get out and spent nearly an hour in the ditch before passers-by spotted him and hauled him out. Despite their best efforts to warm him up, the man remained severely chilled, largely thanks to the air temperature being a biting -2°C. Shortly after the paramedics arrived, he fell unconscious, stopped breathing and went into cardiac arrest. It would be seven hours before his heart started beating properly again, and for five of those he was technically dead. Somehow the extreme cold – the very thing that had…

“THE COSTS OF GEOENGINEERING ARE LOW, ITS EFFECTS WILL BE FELT QUICKLY AND GLOBALLY” I’ve been working since 2009 to understand the potential and limits of geoengineering, and Clive Hamilton paints a picture of this technology that I simply do not recognise. To address climate change, carbon dioxide emissions will have to be driven to zero, but however fast emissions are cut, the climate will still warm considerably over the 21st Century. It’s here that stratospheric aerosol geoengineering could prove an extremely useful tool. Higher temperatures mean more intense heatwaves; they mean air carries more moisture, causing more intense floods; and they mean more melting of the glaciers, driving up sea levels. Reducing temperatures will reduce these risks, and our work has shown that it doesn’t make much difference whether…

Most of us are all too familiar with the unpleasant symptoms of food poisoning, from vomiting to diarrhoea and debilitating stomach cramps. Although viruses play a role, bacteria are common offenders, with Salmonella and Campylobacter topping the poisoning charts. Some bacteria wreak havoc by multiplying in the body before delivering their toxins, which spark an immune reaction in the gut. Others, such as Staphylococcus aureus, poison us by contaminating food with toxins. 1. Bacteria enter Some bacteria or enterotoxins (intestinal toxins) can survive harsh stomach conditions, making their way to the gut. There, the misery begins, sometimes up to 72 hours after eating the offending meal. 2. Bacteria multiply Undetected by the body’s immune system, the bacteria quietly multiply, producing toxins. These invade and penetrate the gut lining, setting off…

1933 Swiss astronomer Fritz Zwicky proposes the existence of dark matter after noting a discrepancy between the calculated mass of the Coma galaxy cluster and the mass of visible matter. 1970 Cornell University’s Vera Rubin notices that galaxies at the edge of the Universe move faster than expected. She suggests dark matter as the cause. 1981 Israeli physicist Mordehai Milgrom proposes that the mass of the Universe is correct, and that it’s Newtonian mechanics that needs updating. He dubs the theory MOND, or Modified Newtonian Dynamics. 2009 Construction on the LUX experiment begins in South Dakota. The experiment aims to detect Weakly Interacting Massive Particles (WIMPs), a hypothetical particle candidate for dark matter.…

1.5 MILLION The number of Adélie penguins in a super colony in the north Antarctic that was discovered by accident when scientists noticed huge patches of poo in images taken by the American Landsat satellite. 6 TONNES The weight of the Hispasat 30W-6 satellite that was recently launched by a SpaceX Falcon 9 rocket – the largest ever put into geostationary orbit. 16 DAYS How much earlier in the year spring now arrives in the Arctic, thanks to climate change over the course of the last decade.…

At the University of Leuven in Belgium, a team of researchers has identified a set of 15 genes that they believe determine our facial features. This research could benefit surgeons attempting to reconstruct the faces of burns and trauma patients, archaeologists who’ve unearthed human remains, and police forensic investigators who only have DNA evidence to identify victims. In the past, scientists selected specific features, such as the distance between the eyes or the width of the mouth, then looked for a connection between these features and the genes. A number of genes have been found using this method, but it’s limited by the fact that only a small set of features are tested. In the new study, the researchers used a database of DNA along with 3D images of subjects’…

Michael is a science writer and broadcaster, who presents Trust Me, I’m A Doctor on BBC Two. His latest book is The Clever Guts Diet (£8.99, Short Books). The great thing about making science documentaries is that you constantly discover things that surprise you. I first came across High Intensity Interval Training (HIIT) more than five years ago while making a documentary for Horizon. At the time, I learned that just three minutes a week of intense cycling could greatly improve aerobic fitness and blood sugar control. I kept in touch with the scientists, and was delighted to get another chance to try out HIIT. This time it was for a recent BBC documentary, The Truth About Getting Fit, and the novelty was that the HIIT protocol was now even…

Daimler dazzled at the Geneva Motor Show with its new Digital Light technology, which it will roll out in the first half of 2018. The computer-controlled high-definition headlights project information onto the road ahead, including warnings if you’re speeding, or if you’re travelling too close to the car in front. The lights also tell you when you’re drifting out of your lane, warn of low-grip conditions, show you how wide your car is, and point an arrow at any pedestrian who looks in danger of stepping onto the road. The technology is part of Daimler’s ‘Intelligent Drive’ strategy, and integrates information from the car’s sensors and GPS data. It displays that information using the one million micro-reflectors on the surface of each headlight, which will automatically dim to avoid dazzling…

INTRODUCING FLIPPY Pasadena’s CaliBurger employed its first burger-flipping robot, creatively named Flippy. Flippy covered the busy 11am ’til 2pm lunch shift, but was withdrawn after just one day. DRIVERLESS OXFORD Driverless cars have taken to the streets of Oxford, in a £6.8m trial. Oxbotica, the company running the trial, is testing the cars on Oxford’s narrow streets, and hopes they’ll soon be able to drive themselves to London. SNOWBOTS Just Eat’s robots successfully navigated the snow to deliver takeaways to customers in Milton Keynes during Storm Emma. The robots have completed over 1,000 deliveries since their 2016 launch, and have now proven themselves in tough weather.…

1 Within the first 20 seconds of cardiac arrest, tissues start to deplete their reserves of oxygen, and toxins build up in the brain. 2 If blood flow is restored, tissue damage in the brain continues. Such ‘reperfusion injury’ is thought to be caused by the production of free radicals when blood returns to oxygen-depleted cells. 3 Cooling the body after cardiac arrest reduces the brain’s metabolic rate, slowing reactions that cause cell damage. For each 1°C drop in core temperature, the brain’s metabolic rate decreases by 6-7 per cent. 4 Doctors use cooling blankets, pads or ice-cold instruments to reduce the body temperature to 33-36°C. Cruder temporary measures, such as applying bags of frozen food, have also been employed. 5 After resuscitation, patients are kept cold and unconscious for…

A long with petting puppies and having just one more chocolate, I’ve added another thing to my list of temptations that humans can’t resist: knuckle-cracking. I mentioned this odd habit in a talk that I used to give quite regularly, and almost as soon as the words were out of my mouth, the popping from the audience began. In the most extreme cases, usually large auditoriums full of teenagers, it would grow like an avalanche: a few lone snaps at the back of the room rolling forwards in an impressive crescendo as everyone else joined in. But finger joints are tiny, and the process of cracking (pulling on a finger joint until it pops) is relatively gentle. What’s making this distinctive sound and why is it so loud? The first…

The most famous of all comets was certainly seen by the English astronomer and mathematician Edmond Halley when it flew round the Sun in 1682, but he did not discover it. The credit for that goes back at least another 2,000 years to 240 BC, when unknown Chinese astronomers noted what they called a ‘broom star’ appearing in the eastern sky in May of that year. Halley’s claim to the name stems from his crucial discovery about the nature of the eponymous object. While studying a list of comet observations over the centuries, he noticed that the years 1531, 1607 and 1682 all featured the appearance of one of these supposedly capricious portents of doom. Was it just a coincidence that they were all about 76 years apart? Using Newton’s…