Sommaire pour April 2024 de BBC Science Focus Magazine

Orcas may not have the same fearsome reputation as great white sharks, but, as surprising new footage reveals, they're more than a match for Hollywood's favourite predator of the deep. Videos captured by tourists and scientists aboard a boat off the coast of Mossel Bay, South Africa, show a lone orca killing and devouring a great white. Such an event has never been seen before. “The astonishing predation represents unprecedented behaviour underscoring the exceptional proficiency of the orca,” said the paper's corresponding author Dr Alison Towner from Rhodes University, South Africa. The videos of the event, which took place in 2023, were crucial to scientific observations published in a new study in the African Journal of Marine Science. Those on the boat watched as a 2.5m (8.2 ft) juvenile great…

Some pre-packaged foods, such as pasta and rice, are staples that many of us eat as part of a balanced diet. Others, such as crisps and sugary snacks, are clearly not health foods. But for some packaged and processed foods, the claims on the label can make it hard to decide what's healthy and what isn't. With a recent study showing diets high in ultraprocessed foods increase the risk of more than 30 health outcomes (including cardiovascular disease and mental ill-health), the level of processing and its effect on our bodies is now under greater scrutiny. But exactly what constitutes an ultra-processed food isn't always clear, certainly not from the labels on such foods. There are some that obviously fall into that category, but there are others that you might…

INNOVOTTONS PREPAE YOURSELF FOR TOMORROW There are many ways to live a healthier life. Regular exercise, a better diet and even something as simple as a daily sudoku puzzle to keep your brain active. But for something a bit different, what about sending electrical shocks to your brain? Neuromodulation involves sending electrical shocks straight to your nervous system for a host of supposed health benefits. It could be the latest tech trend to help you effortlessly upgrade your life. It's not a new idea. Neuromodulation has been around for years, but relied on implants to deliver the electrical stimulation directly to the nervous system. The recent development of wearable devices capable of delivering similar stimulation has renewed interest in the practice, with a few companies such as Parasym and gammaCore,…

M ay I have your attention, please? I'll try and be quick, as I probably only have about 47 seconds before your mind starts wandering. That, according to psychologist Dr Gloria Mark, from the University of California, Irvine, is now our average attention span, based on her latest study of people's use of screens in the workplace. When her team conducted a similar study back in 2004 (before anyone had a smartphone and there was no such thing as TikTok) we could focus for two and a half minutes before wanting to switch to something new. Of course, these figures have their limits. Your declining concentration when grinding out a report may not mean your overall focus levels are collapsing. After all, if you were sent a long message about…

Yes, black holes can die, but in a very slow and mundane fashion. Empty space isn't actually empty. Although it contains no mass or energy, the ‘quantum fields’ that define mass and energy still exist. These fields, because they're not required to have zero energy, can create pairs of ‘virtual particles’, normally a particleantiparticle pair, which quickly annihilate each other. But, according to the usual explanation, near a black hole, it's possible for one of those particles to disappear inside the black hole, while the other one escapes as ‘Hawking radiation’. To conserve the total energy of the black hole, the infalling particle must carry ‘negative energy’ (and hence ‘negative mass’) and the escaping particle must have positive energy. Hawking radiation is the result of how gravity affects space-time. The…

Earth is constantly bombarded by ‘micrometeorites’; tiny bits of asteroids and comets. Scientists have measured the typical accretion rate of these particles at between 20 and 60 million kilograms per year. So, on average, more than 100,000kg fall to Earth each day. The mass distribution of these particles peaks at about 1.5×10–5 grams, with a diameter of about 200 micrometres (1mm = 1,000 micrometres). So, on average, there'll be about 6.7×1012 micrometeorites falling to Earth each day. If these fall uniformly across Earth's surface (which is not perfectly true), each 75m2 (807ft2)of Earth's surface would receive one micrometeorite per day. If we also assume these particles are falling vertically and the average human head has a diameter of 14.4cm (5.5in), then you have about a 1 in 4,600 chance of…

ASTRONOMY FOR BEGINNERS The star Arcturus is an iconic sight in the spring night sky. It's easy to locate by extending the arc of the handle of the Saucepan (aka Plough) away from the pan. Arcturus lies on this curve, shining with a noticeable orange hue. For those of us who live in the northern hemisphere, it's an important object, being the brightest night-time star in this half of the sky. The brightest night-time star is Sirius, in Canis Major (the Great Dog), but this lies in the southern half of the sky. The northern and southern celestial hemispheres are separated by the celestial equator, which represents the projection of Earth's equatorial plane into the sky. Arcturus sits towards the southern end of a large, kite-shaped pattern representing the body…

PENCILS AT THE READY! ACROSS 7 Majestic lager's re-ordered (5) 9 Personnel reduced in top style (4,3) 10 Family member misses initial happiness (7) 11 Set fire to hill beside church (5) 12 Fancy hat also accessible (2,4) 13 Breaking news from city trial (6) 16 Check off alien voucher (6) 17 Mistake repelled first leader (6) 19 Weight of rock (5) 21 Disentangle a French composer (7) 22 Launch opportunity (7) 23 Extra serious start for conventions (5) DOWN 1 Cart fate about - that's not natural (8) 2 Everyone that is around can form union (8) 3 Setting is a bit of an act (5) 4 Reportedly, some distance is an achievement (4) 5 Colourful fellow always gets infection (7,5) 6 Fletcher's groove (4) 8 Comic is sensational and new (7,5) 14 Silent inlets listen, for example (8) 15 Vigorous tenor relies unwisely on son (8) 18 Shift…

Under the swirling surface of the Solar System's biggest planet, unseen forces hold clues to what is hidden inside the gas giant. Now, a team of scientists from Harvard University say changes to Jupiter's magnetic field indicate the presence of mysterious waves moving deep within the planet. A planet's magnetic field provides a window onto what's going on below its surface. Any changes to these fields can reveal interactions between a planet's magnetism, fluid flow and other forces. Using observations from NASA's Juno spacecraft, the scientists observed that a jet (a high-speed current) deep in Jupiter's atmosphere was fluctuating in roughly four-year periods. Their study, published in Nature, shows that the fluctuations were concentrated in a particularly intense magnetic field on Jupiter known as the ‘Great Blue Spot’. “These changes…

NATURE Hidden away in the dusty vaults of natural history museums is a treasure trove of rare species. Now, a new project brings over 13,000 digitised 3D scans of specimens into public and scientific view. Over five years, the openVertebrate (oVert) collaboration involved 18 institutions performing thousands of computed tomography (CT) scans that are now allowing us to see inside the vertebrates in their collections. There are colourised scans of amphibians, reptiles, fish and dinosaurs… even a humpback whale. The new approach unlocks research possibilities for scientists and researchers, who have already used data from the project to gain astonishing insights into the natural world. For example, the scan of a Spinosaurus (not seen here) has revealed that what was previously thought to be an aquatic dinosaur was likely a…

The recent prevalence of ‘fake news’ may make it seem like misinformation is a relatively modern invention. But wild claims, falsehoods and conspiracy theories have been part of human culture for about as long as it's existed. This is because misinformation originates with, and is spread by, other people; and the people factor has a really strong influence. If you've ever had to communicate an important, but complex, issue to a general audience, you'll be well aware of just how frustrating the people factor can be. You may have terabytes of the most reliable data, meticulously worked-out rebuttals to any possible argument, the most elegant PowerPoint slides and the full backing of every renowned expert in the relevant field. And yet, you can still be less persuasive than someone whose…

ANALYSIS REALITY CHECK On 21 February, a met re-wide (3ft) space capsule landed in the Utah desert after eight months in orbit. Its cargo: a batch of Ritonavir, an antiviral drug used in the treatment of HIV and COVID-19. Carried out by Californian start-up Varda Space Industries, the mission was intended to demonstrate the potential for the automated manufacturing of pharmaceutical drugs in space, possibly paving the way for new and more efficient methods of developing medicines. Varda's W-1 mission launched aboard a SpaceX Falcon 9 rocket in June 2023. The capsule being tested weighed around 90kg (almost 200lbs), even though it's theoretically capable of manufacturing nearly 100kg of products over several months spent in orbit. For this initial mission, however, just a small amount of Ritonavir was manufactured during…

THE TRANSPARENT TV Samsung is the market leader when it comes to TVs and has been since 2006. Quickly and successfully embracing new tech and trends has helped the company maintain that position. Hence, we've seen Samsung's big-screen models go from having 4K resolution to 8K resolution, to being mounted on walls and even disguised as artwork. But now they're going transparent. Samsung's latest offering can act as a normal TV or one that's completely see-through while still capable of displaying high-quality, almost hologramlike images. The TV is razor-thin and has a rear panel that slides up when you no longer want to see what's behind the screen. It looks impressive when seen against the backdrop of a tastefully decorated showroom, but might lose some appeal when you consider how…

It's a rather delicious irony that one of the most valuable things to come out of the space programme wasn't the ability to look into the deepest regions of the Universe, but to look back at Earth; to see our world as a beautiful disc of white clouds, blue oceans and multicoloured continents. Since Sputnik, the first artificial satellite, was launched more than 70 years ago, an armada of Earth-observation spacecraft has been put into orbit. Together with more than a century and a half of consistent Earth-based weather measurements, the data these satellites have gathered has allowed us to develop a much better understanding of our planet's climate and our effects upon it. As is now well known, Earth's climate is changing, with average global temperatures increasing. This occurs…

FEATURE | ROGUE PLANETS Imagine a world where the sun never rises. A planet that doesn't even have a sun. A place with no pastel-painting-sunsets and no dawn choruses, just a constant veil of faint stars twinkling in a perpetual, indelible inky night. This unfamiliar scenario would be the reality for any life calling a starless planet home, such as one that's somehow become untethered from its star, rendering it free to wander through the Universe. When we think about planets, we usually picture the eight worlds of our Solar System silently orbiting the central star that's pulling on invisible gravitational strings to keep them close. Yet in recent years astronomers have uncovered an increasingly large population of a very different kind of planet. Worlds that no longer orbit a…

Whether cats or dogs are cleverer is a perennial question. There's no denying dogs normally have bigger brains (especially if they're a bigger breed). But pooches also have more neurons – one golden retriever was found to have 623 million neurons in its cerebral cortex, compared to 429 million for a smaller dog and 250 million for a cat. The dogs also had more neurons in their brains overall. Of course, it's not how many neurons you've got, but what you do with them that counts. There's more research on canines than felines, so dogs’ abilities are better known. And, of course, studying pet cats is hard because they don't like to go to new places, like a laboratory for example (think of how they hide whenever the cat carrier…

Q&A NATURE'S WEIRDEST CREATURES Think all hedgehogs are spiky! Think again. The aptly named furry hedgehog sports a fine pelt of floof with ne'er a prickle in sight. Furry hedgehogs, also known as gymnures, are found in the subtropical evergreen forests of Southeast Asia, including Vietnam, Sumatra, China and the Malay Peninsula. Their pointy snouts are hedgehog-like and their naked tails are rat-like, but there's also something of the shrew about them. They're not, however, closely related to rats, and instead nestle happily within the family of Erinaceidae, which incorporates both furry and spiky hedgehogs alike. Where regular hedgehogs have spines made from stiff, hollow, keratin-dense hairs, furry hedgehogs, which are thought to have evolved before their spiky relatives, are covered in dense fur. Depending on the species, the fur…

Compliments can be a minefield. In fact, psychologists in Belgium have identified a number of ways that compliments can make the person being complimented feel uncomfortable. As soon as someone pays you a compliment, you might feel judged and self-conscious. For instance, if you meet up with friends and one of them pays you a compliment about your outfit, you might feel an uncomfortable sense of being in the spotlight. Social awkwardness or inappropriateness can also be a factor, for instance, if your boss pays you a personal compliment. Aside from these, you might also feel indebted to the person complimenting you and under pressure to reciprocate; or you might feel misunderstood (perhaps the compliment is at odds with your feelings about yourself); or you might feel undeserving – if…

Slow running is a fitness trend with some hard and fast science behind it Deceleration isn't really in the runner's vocabulary. For many of the people who do it, from Olympic champions to 5K enthusiasts, running is the pursuit of speed itself; a sport defined by personal bests, competition, st riving and St rava. Slow? That's a four-letter word. Or at least it was, until quite recently. In the last year or two, slow running has become ‘A Thing’, backed not just by wellness gurus on Instagram, but also by a growing number of coaches, amateur runners and exercise scientists, too. The thinking is that going slow could be a fast way to enjoy the benefits of exercise. “Slow running helps to reduce resting blood pressure, for example. And it…

LETTER OF THE MONTH In the shadows In ‘The Counterintuitive Cosmos’ (February, p73) you mentioned Eratosthenes measuring the size of the Earth. He would have needed an accurate measurement of the distance from Alexandria to Syene, about 1,000km (620 miles) and a very accurate way of measuring time. How could he have done this? Anthony Fenwick-Wilson, Shropshire Marcus Chown replies: Ancient people were smart! While working at the library in Alexandria, Eratosthenes learned that on the first day of summer there were no shadows cast in the Egyptian town of Syene. So he needed only to observe the shadow of a vertical pillar at Alexandria on the same day. He made his estimate of the distance between Alexandria and Syene from the time it took walkers, who were trained to…

MEDICINE Scientists have used artificial intelligence (AI) to make a discovery about prostate cancer that has the potential to save thousands of lives. Prostate cancer is the most common cancer to affect men, with 52,000 cases of the disease diagnosed in the UK each year. But the AI revealed that it's not just one disease; it's actually two. An international team including scientists from the Universities of Oxford, Manchester and East Anglia, used AI to look for changes in the DNA of samples taken from 159 prostate cancer patients. The AI revealed that there were in fact two distinct types of prostate cancer affecting them. “Our research demonstrates that prostate tumours evolve along multiple pathways, leading to two distinct disease types,” said the study's lead researcher Dr Dan Woodcock, of…

A major new study could rock people's opinion of timerestricted eating (a form of intermittent fasting), after finding the practice could significantly increase the chances of death due to cardiovascular disease. The new research, presented to the American Heart Association, claims that restricting your eating to a period of fewer than eight hours per day raises your risk of death due to cardiovascular disease by a staggering 91 per cent. The study evaluated 20,000 participants’ diets and health outcomes over a period of 17 years. However, it failed to identify even one cause of death for which the risk was reduced by restricting eating to an eight-hour window. A total of 2,797 deaths were recorded among the participants in the study, 840 of which were from cardiovascular causes. The average…

The UK Government recently launched a consultation that seeks public and industry opinion on doubling the legal power output (not speed) of ebikes sold in the UK from 250W to 500W. The plan has sparked concerns within the fire safety community. There's a wide range of batteries used on ebikes, but those currently in commercial use are all based on lithium-ion technology. They're battery packs made of individual battery cells (which can be cylindrical or box-shaped), connected together to provide the required voltage and capacity to power the bike. While ebikes and escooters offer a great way to get around a city, if the batteries become damaged or fail, they can start incredibly ferocious fires that can quickly spread out of control. And incidents of fires involving lithium-ion batteries are…

…AN EBIKE WITH UNIQUE LOOKS The Frankenstein's monster of the ebike world, BMW's new CE 02 looks like a bike made with parts from at least three others. The end result is modern and stylish, can cover 90km (55 miles) on a full battery, will go from 0-50km/h (0-30mph) in three seconds and charges from 20-80 per cent in a claimed 100 minutes. All of this makes it a great bike for getting around town, but not so much for long journeys. All the same, it can be specced with a range of bags offering storage for ‘adventures’ (albeit ones fairly close to home). BMW CE 02 bit.ly/BMWCE_02, £8,450 …A SLEEPING BAG YOU CAN WALK IN The warmth of a sleeping bag inside a cold tent is an experience like…

FEATURE | BED BUGS Bed bugs have been around longer than humans. When researchers used bed bug DNA to get an idea of when they first evolved, they found that the ancestors of today's bed bugs were already tiny but successful predators over 115 million years ago, during the reign of the dinosaurs. What they were preying on back then, we don't know, possibly ancient birds. What we do know is that when the first bats appeared, bed bugs were present. A few enterprising individuals crawled into the caves where bats slept to enjoy a hearty meal. From there, several species of bed bugs evolved to feed on their blood, according to the research of Prof Klaus Reinhardt, an evolutionary biologist at University of Tübingen, Germany. As early humans took…

In the depths of winter, when conditions are just right, glittering clouds turn the polar skies into a spectacle of colour. Rainbow clouds – also known as ‘nacreous’ or ‘mother-of-pearl’ clouds after their resemblance to the iridescent shells of some molluscs – are an extremely rare atmospheric phenomenon. Known scientifically as ‘polar stratospheric clouds’, they're found much higher in the atmosphere than clouds normally form. Most clouds are found less than 10km (6 miles) above Earth's surface. But rainbow clouds form at altitudes between 15 and 25km (9 and 15 miles), in an atmospheric layer known as the lower stratosphere. Usually, the stratosphere is far too dry for clouds to form, but when the air temperature drops below about -80°C (-112°F), the sparse water molecules group together to form tiny…

That all hinges on what you consider to be cute. Depending on the species, a newborn shark can be anything from an adorable, hand-sized tiddler, like the small-spotted catsharks that hatch from ‘mermaid's purse’ egg cases, or they can emerge directly from their mothers, with bodies as long as your outstretched arms. This is the case with sand tiger sharks, and how these baby sharks get so big is rather shocking. Sand tigers are one of many species of sharks in which fertilised eggs hatch inside the female, then develop in her uterus. It's quite common for unborn shark embryos to feed on unfertilised eggs, which happens in more than a dozen species. Sand tiger shark embryos go further – ultrasound scans of a pregnant sand tiger shark detected embryos…