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WE LCOM E “I have no special talent. I am only passionately curious” – Albert Einstein. It turns out the scientist who figured out the laws that govern life, the Universe and everything didn’t consider himself to be particularly clever. Instead, his conversations with his biographer reveal that he thought his real gift was curiosity. He would work longer and harder at solving a problem than others, he thought, because he couldn’t be happy not knowing, not understanding how things fit together. He needed a solution. Here at Focus, we like to think we share a smidgen of Einstein's curiosity. We want to know how things work, and we want to know how they're going to make the world a better place. To give you a taste of Focus, we put together this sampler from snippets of the full magazine. If you enjoy this sampler, subscribe, and with every issue, Focus will chart the most exciting new ideas and breakthroughs on the planet. Our team of scientists, doctors and expert writers explain how advances in the worlds of science and technology are creating a better, brighter tomorrow. Whether you're fascinated by space exploration, obsessed with health or passionate about the natural world, we'll bring you the most important developments from around the globe. And if you're interested in tech we'll help you stay ahead of the curve and discover how the latest innovations are shaping our future. Finally, if this issue leaves you with some burning questions of your own, you can write to us and we'll get our expert panel on the case. I hope you enjoy the issue, and if you do be sure to subscribe using the code opposite. Enjoy!

Find out why this bird is wearing 3D glasses � p11

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Masked men ASARO MUD MEN, EASTERN HIGHLANDS PROVINCE, PAPUA NEW GUINEA Some of us may smear mud packs on our faces to improve our looks, but not these guys. Hailing from Goroka in the Eastern Highlands Province of Papua New Guinea, the Asaro mud men resemble something from a twisted nightmare. The legend surrounding their appearance claims that when an enemy tribe attacked, they ran to the nearby Asaro River to hide. They waited until dark before emerging covered in thick mud, unaware that their attackers were still there. Upon seeing the eerie figures materialising from the darkness, the enemy tribe fled, believing them to be vengeful spirits. Rumours spread that they were imbued with the supernatural powers of the river spirits, so the crafty elders decided to capitalise on this and created a new dress code for their warriors. To further the effect, they fashioned the clay into terrifying masks with exaggerated features studded with the teeth and tusks of wild boar. In todayâ&#x20AC;&#x2122;s more peaceful times, the mud menâ&#x20AC;&#x2122;s impressive displays are limited to scaring the wits out of paying tourists rather than neighbouring enemies.

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News, in ISSUE: and com ter views the mos ment on t break threxciting ou in the w ghs orld.

SPACE

SEVEN EARTH-SIZED EXOPLANETS FOUND

PHOTO: NASA

The system of planets found orbiting nearby dwarf star TRAPPIST-1 may be our best chance yet of finding alien life TRAPPIST-1, an ultracool dwarf star located just 40 lightyears from Earth in the Aquarius constellation, was first detected by researchers from Liege using the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile, and later confirmed by NASA’s Spitzer Space Telescope and the Very Large Telescope, also in Chile. The planets were detected by observing dips in the star’s light output caused by each of the seven planets passing in front of it, events known as transits. The researchers found that all of the planets are comparable in size to the Earth, while density measurements suggest that the innermost six are rocky.

Current climate models suggest the three innermost planets are probably too hot to support liquid water, and the one furthest from the star is too cold. However, the remaining three sit comfortably within the habitable zone and could host oceans of surface water – a feature thought to be essential for the existence of life. “The energy output from dwarf stars like TRAPPIST-1 is much weaker than that of our Sun. Planets would need to be in far closer orbits than we see in the Solar System if there is to be surface water,” said researcher Dr Amaury Triaud. “Fortunately, it seems that this kind of compact configuration is just what we see around TRAPPIST-1.”

DISCOVERIES

As the planets in the TRAPPIST-1 system are so close together, they’d be visible in each other’s skies, as seen in this illustration

The star is relatively small, just 8 per cent the mass of the Sun, and would appear to glow salmon pink when observed from the surface of the planets, the researchers say. Now that astronomers know that the planets are there, the next job is to find out what they are really like. The first step is to make an accurate determination of their densities. When searching for habitable worlds, rocky planets are the clear preference because – put simply – they provide a surface for life forms to walk, slither or otherwise move across. The European Space Agency (ESA) will launch CHEOPS (CHaracterising ExOPlanet Satellite) in 2018. The main science goals of the mission are to measure the densities of planets with radii between one and six times of Earth. The TRAPPIST-1 system will be high on the list. The next step will be to analyse the planets’ atmospheres to see if any look like they could be habitable. “The main goal will be trying to detect the signature of water,” said CHEOPS scientist Dr Vincent Bourrier. Water vapour in a planet’s atmosphere could betray widespread oceans and a water cycle. Its signature appears in the infrared region of the spectrum and this is where the NASA-built James Webb Space Telescope (JWST) comes in. ESA will launch the JWST in the same year as CHEOPS. With its 6.5m-diameter infrared mirror, JWST will make analysing exoplanet atmospheres easier than ever. One of its first targets is likely to be the seven worlds of the TRAPPIST-1 solar system. 8

“ROCKY PLANETS ARE THE CLEAR PREFERENCE BECAUSE THEY PROVIDE A SURFACE FOR LIFE FORMS”

While finding water vapour would increase the belief that the planet under investigation is potentially habitable, there are other factors that could affect a planet’s ability to support life. To investigate those, Bourrier and his team have already used the Hubble Space Telescope to look at the ultraviolet signature of TRAPPIST-1’s two innermost planets. His work shows that those planets could have had their atmospheres completely eroded away by the radiation from the star – rendering the planets barren. Could this have happened to the other worlds of TRAPPIST-1? Actually proving that a planet is habitable may be really tough. Astronomers will have to look for ‘biomarkers’. These are gases that only exist together in an atmosphere because they are being replenished by the metabolisms of living creatures. Oxygen and methane are good examples in our own atmosphere. So far, there are no firm plans to build a space telescope capable of making such an exacting measurement, although NASA and ESA have both studied engineering concepts. NASA’s next exoplanet mission, the Transiting Exoplanet Survey Satellite (TESS), also launching next year, could reveal many more solar systems like TRAPPIST-1. This mission will survey 200,000 stars and is expected to discover thousands of exoplanets, from the size of Earth up to Jupiter and larger.”

Stuart Clark is an astronomy writer. His most recent book is the The Search For Earth’s Twin (£20, Quercus).

PHOTOS: NASA X3

EXPERT COMMENT

STAR Mercury

1b 4

1c Venus 2

1d Earth

Mars

TRAPPIST-1 solar system

Our Solar System

Asteroid belt

1h 8

Hot and cold This illustration compares the energy received by TRAPPIST-1’s planets, relative to Earth. TRAPPIST-1’s planets are named 1b-1h. It is thought that 1b, 1c and 1d are probably too hot to support liquid water, and 1h is too cold. But the other three could host oceans – and therefore life.

TRAPPIST-1 solar system b

1.51

2.42

4.05

6.10

9.21

12.35

~20

0.011

0.015

0.021

0.028

0.037

0.045

~0.06

Planet radius

1.09

1.06

0.77

0.92

1.04

1.13

0.76

Planet mass

0.85

1.38

0.41

0.62

0.68

1.34

Orbital period Days

Distance to star

Astronomical units (AU)* Relative to Earth Relative to Earth

* 1 AU = distance from Earth to Sun

DISCOVERIES

DINOSAURS

DINOSAUR TAIL FOUND TRAPPED IN AMBER This really is a telling tail: researchers from China, Canada and the UK have discovered a dinosaur tail, complete with its feathers, trapped in a piece of amber. The tail, consisting of eight vertebrae surrounded by feathers, belonged to a juvenile bipedal dinosaur that was preserved in midCretaceous amber about 99 million years ago. While dinosaur feathers have been found in amber before, earlier examples have been difficult to link to their source animal. “We can be sure of the source because the vertebrae are not fused into a rod or pygostyle [a triangular plate that supports the tail feathers] as in modern birds and their closest relatives,” said researcher Ryan McKellar. “Instead, the tail is long and flexible, with keels of feathers running down each side. In other words, the feathers are definitely those of a dinosaur, not those of a prehistoric bird.” After investigating the sample with microscopes and CT scanners, the researchers found that the tail probably had a chestnut-brown upper surface and a pale underside. Layers of soft tissue layer around the bones contain traces of ferrous iron, a relic left over from red blood cells trapped in the sample. “Amber pieces preserve tiny snapshots of ancient ecosystems, but they record microscopic details, three-dimensional arrangements, and labile tissues that are difficult to study in other settings,” said researcher Ryan McKellar. “This is a new source of information that is worth researching with intensity, and protecting as a fossil resource.” 10

DISCOVERIES

ENGINEERING

PHOTOS: RYAN MCKELLAR, ERIC GUTIERREZ/STANFORD UNIVERSITY

PARROT WEARING GOGGLES MAY HELP US BUILD ROBOTS THAT FLY MORE EFFICIENTLY In order to investigate the lift generated by a bird’s wings, a team from Stanford University trained a Pacific parrotlet called Obi to fly through a chamber filled with microscopic aerosol particles illuminated with lasers. As he swooped through the air, the researchers were able to record the motion of the laser light that was scattered by the flapping of his wings. The goggles were specially designed to protect the bird’s eyes and also had reflective markers on the side so the team could track his velocity. The measurements revealed that the swirling vortices generated by the bird’s wingtips break up in a sudden, dramatic fashion that current mathematical models of flight fail to account for. According to the researchers, the results help explain the way animals generate enough lift to fly, and could have implications for how flying robots and drones are designed in the future. “Many people look at results in the animal flight literature for understanding how robotic wings could be designed better,” said researcher David Lentink. “Now, we’ve shown that the equations that people have used are not as reliable as the community hoped they were. We need new studies, new methods to really inform this design process much more reliably.” Obi can attract all the birds with goggles like these…

W H AT W E LEARNED THIS MONTH SALTING ICY ROADS IS CHANGING THE SEX OF FROGS Researchers at Yale University have found that chemicals used in de-icing salt can find their way into ponds and change the sex of frogs during the early stages of their lives. The proportion of females could be reduced by up to 10 per cent, potentially damaging some frog populations, they say.

DAYS ARE GETTING LONGER Have you ever moaned that there aren’t enough hours in the day? Well, days will get an hour longer, a team at Durham University has found – just not for two million years. The effect is due to the Moon’s orbit growing by around 4cm a year as the Earth’s rotation slows.

‘ANTACIDS’ COULD HELP US FIGHT CLIMATE CHANGE One key idea for combating climate change is to spray aerosol particles into the atmosphere to reflect the Sun’s rays, but many of the compounds that would be suitable produce acids that damage the ozone layer. Now, a team at Harvard has found that calcite, a constituent found in many antacids, could reflect sunlight while absorbing harmful acids.

‘MAN FLU’ COULD EXIST Men could be harder hit by certain infectious diseases, a team at Royal Holloway University has found. Some bugs have evolved to affect women less than men, so they can be passed on to children through breastfeeding or childbirth, the researchers say.

DISCOVERIES

SPACE

NASA’S MINING BOT GETS ROLLING We definitely dig this. NASA has started testing the Regolith Advanced Surface Systems Operations Robot (RASSOR). This robot is designed to mine resources on the surface of asteroids, the Moon or even Mars. The bot is in development at Kennedy Space Center in Florida. The agency has released a video showing a simulated mission in which RASSOR was used to scoop up regolith, which is the loose, rocky material on the surface of a planet. It then loaded the regolith into a device called a MARCO POLO/Mars Pathfinder in-situ resource

utilisation system. This pulls water and ice out of the regolith and turns their chemicals into fuel or air for astronauts working on the surface. The primary challenge for any digging robot operating in low gravity is that it has to be light and small enough to fly on a rocket, but heavy enough to operate in gravity lower than Earth’s. RASSOR tackles this problem by using digging bucket drums at each end of the robot’s body that rotate in opposite directions, giving enough traction on one end

to let the opposite side dig into the soil. It has a top speed of 4cm per second, five times faster than the Mars Curiosity rover, and is capable of hauling around 20kg of material. “[On Mars] there are some areas at the poles where they think there’s a lot of ice, so you’d be digging in ice,” said NASA engineer AJ Nick. “There’s other areas where the water is 30cm down, so you actually have to dig down 30cm and take off the top and that depth is really where you want to start collecting water ice.” To see the RASSOR in action, visit bit.ly/2eQ7wev

PHOTOS: GETTY X2

NASA technologist Rob Mueller (left) inspects the RASSOR with Apollo astronaut Buzz Aldrin

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DISCOVERIES

MEDICINE

LAB-MADE HUMAN BLOOD IS NOW “TANTALISINGLY CLOSE” Now here’s a bloody good piece of research! A team at Boston Children’s Hospital have generated blood-forming stem cells in the lab for the first time, a breakthrough that could enable the development of more effective treatments for genetic blood diseases To create the cells, the team used a combination of chemical processes and genetic engineering to coax human pluripotent stem cells – cells capable of forming any adult cell – to differentiate into hemogenic endothelium, an embryonic form of tissue that gives rise to blood stem cells. They then implanted the resulting tissue into mice. Weeks later, a small number of the animals began producing several types of human blood cells. Some mice were even able to mount a human immune response after vaccination. “We’re tantalisingly close to generating bona fide human blood stem cells in a dish. This is

the culmination of over 20 years of striving,” said researcher George Daley. “We’re now able to model human blood function in ‘humanised’ mice. This is a major step forward for our ability to investigate genetic blood disease.” Although the cells made from the pluripotent stem cells are a mix of true blood stem cells and other cells known as blood progenitor cells, they proved capable of generating multiple types of human blood cells when put into mice. “This step opens up an opportunity to take cells from patients with genetic blood disorders, use gene editing to correct their genetic defect and make functional blood cells,” said researcher Ryohichi Sugimura. “This also gives us the potential to have a limitless supply of blood stem cells and blood by taking cells from universal donors. This could potentially augment the blood supply for patients who need transfusions.”

I N N U M B E RS

50 DEGREES C

The temperature reached by human mitochondria, the energy factories found in our cells.

100 YEARS

The time the human race has left to colonise another planet to ensure its survival, according to physicist Stephen Hawking.

1.33 x

The lab-produced blood stem cells can develop into different types of blood cell

1029KG

The minimum size a star needs to reach in order to shine, as recently calculated by researchers at the University of Texas at Austin.

INNOVATIONS

CARS

McLaren now 3D-printing F1 parts The recent Bahrain Grand Prix saw the McLaren team bringing something new to the pit stop: 3D printing. Formula 1 teams tweak car and engine component specifications all the time, but it usually takes a little while before a new part – a wider fuel line, say, or a lower-profile front spoiler – is ready for use in a race. To speed up the process, the McLaren team took a Stratasys uPrint SE Plus 3D printer with them to the track, which can produce race-ready parts during the competitive weekend. The printer could even be used to create one-off tools designed to fix

14 14

unique problems. It is hoped that, using this technology, design tweaks can be implemented faster than has previously been possible. Neil Oatley, design and development director at McLaren Racing, said: “We are consistently modifying and improving our Formula 1 car designs, so the ability to test new designs quickly is critical. If we can bring new developments to the car one race earlier – going from new idea to new part in only a few days – this will be a key factor in making the McLaren MCL32 [McLaren’s current F1 car] more competitive.”

ABOVE: McLaren MCL32: now available with 3D-printed parts

INNOVATIONS PLANES

Next-generation aviation Short-haul flights that are up to 80 per cent cheaper and 80 per cent faster sound too good to be true; factor in an 80 per cent reduction in carbon emissions, too, and we’re clearly in cloud cuckoo land! Except Boeing clearly doesn’t think so, because along with US domestic airline JetBlue it has just pumped significant amounts of cash into Zunum Aero, a three-year-old start-up that promises its hybrid electric-kerosene aero engines will offer all of the advantages listed above. The company is currently working with the US Federal Aviation Authority and hopes its planes will be certified for operation in the US by the end of next

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year, with a view to providing domestic flights within five years. Early versions of the planes will have a range of 1,125km (700 miles), but Zunum hopes to have planes with a range of 1,600km (1,000 miles) built by 2030. Zunum Aero CEO Ashish Kumar said: “The shift of the industry to large aircraft and gas turbines has concentrated almost all air traffic to just 2 per cent of our airports, creating a massive transport gap over regional distances. Hybrid propulsion is an industry-changing solution, enabling mid-sized aircraft on regional routes to have better cost efficiencies than airliners.”

We explo SUE: re groundb r e a k in gt set to sh ape our ech f ut and test some of ure smar tes t t gadget he s on the plan et .

TECH BYTES

FASTER BANKING The UK’s Cheque & Credit Clearing Company has started implementing an industry-wide, high-res, secure imaging system that will negate the need for banks to physically send cheques for clearing – meaning that cheques will soon clear in 24 hours rather than 72.

FLYING SQUAD Devon And Cornwall Police is setting up a ‘drone squad’ that will operate on a 24/7 basis. The squad is the first of its kind in the UK and will use drones to monitor road traffic accidents and search for missing persons.

PHOTOS: GETTY, THATCHERKELLEY.COM

SECURITY IS WRITTEN IN YOUR PALMS

Zunum’s planes could offer more efficient short-haul flights

Fujitsu is developing a biometric identification system based on the unique pattern of veins in your hand. ‘PalmSecure’ is said to be more accurate than fingerprint or voice identification, and Fujitsu is already working on embedding the tech into its next-generation PCs.

COVER COVERSTORY STORY

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Whethe Y ISSUE: know ho r you want to w how the memor y works , Un or how w iverse formed e k n ow wha dinosaur t s lo demystif oked like, we y th ideas in e biggest science.

HERE COME THE

NANO MEDICS COMING SOON TO A GP NEAR YOU: MICRO MACHINES THAT WILL CLIMB INTO YOUR BODY, DETECT DISEASE AND CURE IT BEFORE YOU EVEN KNOW YOUâ&#x20AC;&#x2122;RE ILL Words: Tom Ireland

ILLUSTRATION: ANDY POTTS

ABOVE: The plot of sci-fi film Innerspace no longer seems quite so outlandish

“Diabetics could simply shine a torch on their arm to top up their insulin”

technology smart enough to find and treat the causes of diseases.

SMALL SCIENCE

The simplest nanomedicines are spherical particles that carry a payload of drugs. Smaller than human or bacterial cells, but larger than individual molecules, the spheres are tiny enough to penetrate cells. The term ‘nano’ is used to describe objects smaller than 100 nanometres, with one nanometre being a billionth of a metre. Particles at this scale have different properties than if they were larger. Nanomedicines are large enough to stay in the bloodstream for longer than normal medicine molecules, yet they are not so big that they clog up blood vessels. Scientists can even attach biological molecules to the outside of nanoparticles to ensure, for example, that they are attracted to specific molecules in the body – such as those found in tumours. Or, by making nanoparticles with more complex shapes, scientists can effectively create tiny machines that use chemical reactions to become unimaginably small motors or lightemitting globes. Some nanomachines can even puncture a hole in cell membranes, much like how a virus injects its DNA to infect a host cell. By putting these elements together – payload delivery, molecular recognition and pore

PHOTO: KOBAL COLLECTION

he 1980s sci-fi film Innerspace sees a submersible and its pilot shrunk to microscopic size before being jabbed into a shop attendant, and much hilarity ensues. The plot took its inspiration from 1960s classic Fantastic Voyage, in which a miniaturised crew are injected into a dying scientist and must attempt to remove a clot from his brain. Both films seemed pretty crazy when they came out, but the extraordinary ideas featured no longer seem quite so far-fetched. Tiny cameras can now be swallowed, while electrodes can be placed deep within the brain. And increasingly, nanotechnology tiny enough to be injected into the bloodstream is the focus of new treatments for diseases like cancer. These ingenious devices are expected to revolutionise medicine in the coming decade – they’re small enough to flow through the body’s tiniest blood vessels, yet are packed with

THE NANO TOOLKIT How do you make a machine that’s small and smart enough to travel into the body and blast a tumour? POLYMERS

Polymers are materials that form hollow balls that can then be filled with tiny amounts of other useful chemicals.

GRAPHENE

A type of carbon that forms sheets just one atom thick. The material is strong and highly unreactive, so can be used to create a range of tiny objects.

CARBON NANOTUBES

Sheets of graphene rolled up into tiny tubes (‘nanotubes’) have been a key component in nanotechnology for years. These tubes could be used on the ends of ‘nanoneedles’, allowing them to inject substances into specific areas of individual cells.

QUANTUM DOTS

puncturing – scientists can create vessels capable of travelling to the site of a tumour, for example, and treating it directly.

PHOTOS: SCIENCE PHOTO LIBRARY X3, GETTY X4

ON TRIAL

Only around a dozen nanomedicines are licensed for use at the moment, but hundreds more are in development or undergoing clinical trials. Imagine, for example, being able to release drugs into your body by shining a torch onto your arm rather than having an injection. Well, researchers at the University of California, San Diego might just have made that a reality. They’ve developed ballshaped nanoparticles made from a polymer that falls apart when UV light is shone on it. This simple system means the nanoparticles release their medical payload wherever light is shone into the body. The researchers foresee a time when diabetics could shine a torch on their skin to top up insulin. Meanwhile, a microscopic, injectable ‘nanoparticle generator’ was recently found to yield ‘astonishing results’ in the treatment of lung and liver cancers in mice. These drug-filled containers can deliver higher doses of drugs to the cancerous cells than medicines dissolved in the blood. Healthy tissue is therefore spared the toxic effects of a high dose. Clinical trials on the first human patients could begin as early as next year. 2

TOP: A single human cell rests on a bed of nanoneedles ABOVE: Quantum dots can be engineered to emit light at specific wavelengths

Quantum dots are tiny spheres that are small enough to pass freely through cells. They have a metal inner core and an outer casing. Some emit light, which can be used signal the presence of disease.

DNA

DNA’s ability to self-assemble into complex shapes makes it an ideal material for making devices on a tiny scale. Scientists have already created DNA-based shapes that can act like tiny motors or boxes.

PROTEINS

Like DNA, proteins are capable of assembling themselves into large, complex, and highly predictable shapes. New shapes and functions can be designed by altering the sequence of subunits from which the proteins are made.

VIRUSES

Viruses are nature’s own nanomachines. Barely considered living organisms, they are often made of just a few proteins and strands of DNA. Yet they can still infect host cells to make copies of themselves. Bolting useful medical functions onto existing viruses is a promising area of nanomedicine under development. 19

2 Nanomedicine is not just about the delivery of drugs through the bloodstream. There are numerous other ways nanotechnology could transform medicine, says Prof Kostas Kostarelos, chair of nanomedicine at University College London. He is helping to develop ‘nanoneedles’ that could extend surgeons’ tools to unimaginable levels of fineness and precision. “This could offer surgeons an extension of the syringe or scalpel at the nanoscale, which could deliver therapeutics to individual cells, or even allow them to manipulate individual cellular components,” says Kostarelos. “They would use molecular recognition so that the tip associates with a particular structure.”

Scientists also believe nanomedicines will be used to send signals about conditions in the body. For example, nanoparticles known as ‘quantum dots’ have a metal inner core and a protective shell. This structure gives them unique optical properties, allowing the particles to modified so that they can give off fluorescent light in the presence of certain disease, which is then picked up in a scan.

Visualisation of quantum dots attaching to a tumour on the wall of a blood vessel

MATERIAL WORLD

Nanomedicines can be roughly classified as ‘hard’ and ‘soft’ depending on the substances used to build them. ‘Hard’ nanomedicines often use materials like graphene, a type of carbon that can be made into sheets just one atom thick. These sheets can be used

S IZE SC A LE (w i d th) Electron microscope

Water molecule

0.1nm 20

Glucose molecule

1nm

Quantum dots

10nm

DNA nanobot

25nm

Virus

Bacteria

100nm

1,000nm

YOUR FUTURE DOCTOR Could this be how nanoparticles keep us healthy in 2050? 1. Nanobots that detect signs of common diseases are injected into the blood soon after birth.

PHOTOS: SCIENCE PHOTO LIBRARY, GETTY X5, ISTOCK X3

2. Signs of cystic fibrosis are detected. A modified virus ‘infects’ cells with gene-editing technology, repairing the genes that cause the disease.

3. On developing diabetes at 30, light-sensitive, insulin-producing quantum dots are injected into the body. To top up insulin levels during the day, a special torch is shone onto the blood vessels on the wrist, where the skin is thin. 4. At 60, a scan reveals weak

fluorescent light being emitted from deep in the lymph nodes. Nanobots are reacting with molecules found in cancer cells to signal the disease’s presence. 5. To combat the cancer, more nanobots are injected into the body. They accumulate in

the tumour, making the cancerous tissue glow. Surgeons can then safely remove the tissue without the risk of damaging healthy flesh. Other nanobots are then released into the body which send powerful anti-cancer drugs directly into the cancer cells.

to make tiny atomic-scale shapes such as hollow tubes and spheres, and metals with unusual properties can be embedded within them. But scientists are increasingly focusing efforts on ‘soft’ nanomedicines – particles made from biological materials like proteins, fats and DNA. This research takes its inspiration from the complex molecules made within all cells, many of which perform highly specific jobs and could therefore be considered ‘natural nanomachines’ themselves.

“Viruses can arguably be seen as nature’s nanomachines”

6. At age 90, DNA-based nanobots constantly repair the age-related damage to brain cells that can lead to degenerative conditions. Others scan the DNA in each cell to ensure it is functioning just as it used to when the body was younger.

“Nanobots made from shiny metal are actually pretty far off still – I’m not sure that route is really going anywhere,” says Prof Hendrik Dietz, head of the Laboratory for Biomolecular Nanotechnology in Munich. “We adapt or mimic the methods used to assemble functional molecules in nature. We are looking to do chemistry how our bodies do it, by building enzymes or drug-delivery vehicles that are smarter than current pharmaceutical methods.” DNA, especially, has proven to be the perfect material for scientists looking to build functional objects on a tiny scale. Rather than trying to manufacture components, scientists create a length of DNA with a particular genetic sequence. The way the different subunits of the strand interact with 2

Optical microscope

Cancer cell

Unaided eye

Human hair

40,000 DNA nanobots would fit on this full stop

Baked bean

Tennis ball

10,000,000nm

100,000,000nm

10,000nm

100,000nm

1,000,000nm

The nanobots in this illustration look a little like viruses, which in themselves can be used in nanomedicine

The number of potential uses of nanotechnology in medicine is dizzying. As well as tiny devices, scientists have developed gels that self-organise at the nanoscale into structures that can stop bleeding in wounds within seconds. And a team in South Korea has designed a nanobandage – a dressing that contains stretchable, wafer-thin nanotechnology that monitors a patient’s muscle activity or skin condition, then administers medication as needed.

WHAT NEXT?

This seemingly unending potential has led some to suggest that nanomedicine could make humans virtually immortal within a few decades. Renowned futurist Ray Kurzweil has stated that within the next century he believes DNA-based ‘nanobots’ will eventually be a routine part of our blood, scanning each cell in our bodies for damage to repair. In the shorter term, researchers like Dietz believe that integrating biology-based nanotechnology and traditional engineering could revolutionise the power and efficiency of technology outside of the body too. “The more transistors you can pack into a space, then the more calculations you can do per second,” he says. “A combination of superfine, self-assembling DNA nanostructures and existing technology could help us reach another level of efficiency in computing.”

“Nanomedicines could make humans virtually immortal”

PHOTO: ALAMY

2 each other causes it to fold itself into highly predictable two- and three-dimensional shapes as it is formed. The longer the lengths of DNA, the more complex the shapes that can be formed. Manipulating DNA in this way is known as ‘DNA origami’ and has been used to create objects such as tiny walking machines, boxes that open and close, and self-destructing drug-delivery vehicles. It may be some time before this technology is used in the body, but the complexity of DNA-based nanomachines is already impressive. Scientists have even constructed a microscopic alphabet to show their skill in making DNA form any shape. “No other material can compete with DNA in terms of precision and self-assembly,” says Dietz. “It folds into a precise shape based on the sequence of base pairs we have programmed. These selfassembly methods are much finer than what you can do with traditional ‘top-down’ design.” Other researchers use entire viruses as the basis for their nanomachines. While viruses are normally thought of as harmful infectious agents, they can also arguably be seen as nature’s nanomachines – perfectly evolved to travel deep into their hosts and inject a genetic payload into cells to infect them. Biologists are increasingly using non-deadly viruses to ‘infect’ human cells with new genes in order to replace those that cause genetic disease. The viruses can be shielded from the body’s immune system by altering their outer casing, and – like lab-built nanoparticles – this outer surface can be modified to ensure they target specific cells.

THE DIMINUTIVE DOCTORS Some of the most intriguing nano devices currently being researched Type

How it works

Target

Made from

Benefits

VIRUS

A virus injects its own genes into its host’s cells

Any living organism or cell

DNA and protein

Viruses are already used as nanomachines to deliver replacement genes into cells, including those of humans

MOLECULAR MOTOR

Chemical reactions make sections of a nanoparticle move, propelling it forward

N/A

Complex chemicals such as amino acids or proteins

WORM-SHAPED NANOPARTICLE

Can evade the immune system, which means that the body will not eliminate them

Tumours

Synthetic polymers

Can be made into different shapes for different jobs

DNA NANOBOT

When this DNA-based device recognises a target cell, its two halves swing open to release a payload

Cancer

DNA

Self-assembles, non-toxic

PHOTOS: SCIENCE PHOTO LIBRARY, YONGGANG KE

Computergenerated models of 3D structures that were created from DNA

They could allow bots to move in a specific direction, or break down fatty deposits and clots

For now, the goal is to prove nanotechnologies are safe and effective when used in medicine. As nanomedicines stay in the body for longer than traditional drugs, there is a greater risk that they may have lasting unwanted effects. Those containing certain metals are more likely to be toxic should they accumulate in the body. If the remaining hurdles can be overcome, it heralds a new era in smarter treatments that are tailored to function only in particular areas in the body. These targeted treatments have the potential to make traditional medicines, which act on the entire body, seem crude in comparison. The global nanomedicine market is already estimated at being worth between $150bn (£104bn) and $250bn (£173bn), and will only continue to grow as more treatments are licensed for use. Today’s nanomedicines may not look like the submersible in Innerspace, but they’re arguably far, far smarter. Made from DNA that can build itself and with biological molecules as their navigator, they won’t go wrong or get lost. This tiny technology is coming to a human being near you – and soon.

Tom Ireland is a freelance science writer and also edits The Biologist magazine. D I S C OV E R M O R E

Watch the world’s smallest film, made using atoms, at bit.ly/smallest_movie

HEALTH

PPIE

MEET THE

PEOPLE ON THE PLANET

It’s January. It’s cold. Christmas is over and summer feels a long way off. So how, and why, do the world’s happiest people keep smiling through the long winter months? WORDS: JHENI OSMAN

nce again, it’s been raining all day. It got dark hours ago. And a bitterly cold January night beckons in the city of Copenhagen. Many people would find all this pretty depressing. But not most Danes. In 2016, Denmark was ranked as the happiest nation on the planet in the World Happiness Report. This might sound surprising given that in mid-winter the country is plunged into darkness for 16 hours a day, deprived of that supposed vital ingredient of happiness: sunshine. So what are their secrets? The annual World Happiness Report typically assesses criteria such as: per capita income; life expectancy; people’s freedom to make life decisions; generosity; social support; and corruption in government

PHOTO: GETTY

and business. For the 2017 report, researchers are looking in depth at Africa and China, happiness in the workplace, happiness over the course of life in general, and the sources and consequences of trust – the vital glue for ensuring stable social foundations. “The most surprising thing we’ve found is that building the positives is more important than identifying and curing the negatives,” says John Helliwell, professor emeritus of economics at the University of British Columbia. He co-edits the World Happiness Report and is remaining tight-lipped about who he thinks will take the number one spot this year – results are due in March. “The aim of the report is to increase public and policy awareness of the importance and meaning of internationally comparable measures of the quality of life,” he adds. Helliwell and his colleagues believe that happiness provides a better indicator of 2

HEALTH

DOES MONEY BUY HAPPINESS?

It’s not surprising to learn that wealth does play a small part in happiness. After all, incomes are more than 25 times higher in the happiest countries than in the least happy ones. “Income is one of the bigger elements in explaining international differences,” says Helliwell. “Having at least sufficient material resources is one of the prime supports for a good life. But, of course, they are not the major part of the story.” Meik Wiking, CEO of the Happiness Research Institute, a Copenhagen-based think tank, agrees that money is not the sole root of happiness: “The Danes decouple wealth and well-being. We focus on the small things that really matter, including spending more quality time with friends and family, and enjoying the good things in life.” Wiking is the author of The Little Book Of Hygge: The Danish Way To Live Well. Hygge (pronounced ‘hooga’) is the latest buzzword on the lips of every advertising agent, lifestyle magazine editor and blogger. It is usually translated as ‘cosiness’, but Danes would say it’s much more than that. “Hygge has been called everything from the ‘art of creating intimacy’ to ‘cocoa by candlelight’,” says Wiking. “Some of the key ingredients are togetherness, relaxation, indulgence, presence and comfort. The true essence of hygge is the pursuit of everyday happiness and it’s basically like a hug, just without the physical touch.” Now, before you start thinking that all you need to be truly happy is to win the lottery so that you can settle down in a blissful state of hygge and never lift another finger, think again. Even if you’re wealthy, work is a great tonic for gloominess. “It is not work itself, but how it is done, with whom, and in what circumstances, that creates or destroys happiness,” says Helliwell. “People are happier doing things with other people, especially if they feel they’re doing important things in a friendly and trustworthy environment. This is true for life both in and out of the workplace. People who work in a high-trust workplace and think of their superior more as a partner than a boss are as happy on weekdays as on weekends.” And there we were feeling miserable about the decades of hard toil that stretch ahead of us…

SUBJECTIVE SMILES

So, the next big question: can one really rate happiness subjectively? Surely, surveys are subject to individual bias? We all know how we Brits like 26

to put a brave face on, picnic on a rainswept beach (just because the Met Office told us it was going to be a scorcher), and always say ‘Fine, thanks!’ when someone asks us how we are (even if we’re going through a crushing bout of existential angst, having spilt our cup of tea). “There are three different types of subjective wellbeing measures,” explains Helliwell. “These include positive affect [how we experience positive emotions], negative affect [how we experience negative emotions], and life evaluations, where respondents say how happy they are with their lives as a whole.” According to Helliwell, life evaluations tend to be determined by individual circumstances and are more variable among countries. All three measures are subjective reports based on the individual’s responses – just like when doctors ask patients to report on their pain levels. Yet not all scientists are satisfied with these subjective assumptions. Associate professor Wataru Sato and his team at Japan’s Kyoto University have used scans of the brain to try to determine which area is involved in feeling happy. Their results showed that volunteers who rated highly on happiness surveys had more grey matter mass in the precuneus, which is involved in selfreflection and consciousness. But scientists aren’t just looking at the brain. They are also turning to genetics to determine why some of us are happier than others.

IN THE GENES

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Researchers at Vrije Universiteit in Amsterdam have isolated the parts of the human genome that may explain the differences in how we each experience happiness. After analysing the DNA of over 298,000 people from around the world, the team found three genetic variants for happiness. Crucially, they discovered that two of the variants are linked with differences in the symptoms of depression, a mental disorder that is one of the greatest medical challenges of our time. 2

Denmark’s capital city of Copenhagen, where residents commute by bicycle and there’s always time for a cinnamon bun. What’s not to love?

PHOTO: GETTY ILLUSTRATION: DAN BRIGHT/LOST STUDIO

2 human welfare than separate measures of income, poverty, education, health and good government. And they have found that people are happier living in societies where there is less happiness inequality. However, results show that happiness inequality has increased significantly in most countries, in almost all global regions, and for the population of the world as a whole.

3 5

HYGGE YOUR HOME Meik Wiking, CEO of the Happiness Research Institute, offers his five top tips for creating a cosy sanctuary

MAKE A HYGGEKROG

Letting your fingers run across a warm, wooden table is a different feeling from being in contact with something made from cold steel or plastic.

BRING IN NATURE

As soon as it gets dark, Danes tend to light candles, especially in the winter. Candles instantly create a cosy mood and offer a softer light than overhead bulbs.

Every home needs a hyggekrog, which roughly translates as ‘a nook’. It is the place where you love to snuggle up with a book and a hot drink. 2

Danes feel the need to bring the entire forest inside. Any piece of nature you find is likely to get the green light. Leaves, flowers, pine cones… basically, think how a Viking squirrel would furnish a room. 3

THINK TACTILE

A hyggelig interior is not just about how things look, it is just as much about how things feel.

LIGHT CANDLES

LINGER LONGER

Danes love to linger, particularly after a delicious meal. While many people around the world start to clear up as soon as a dinner party is finished, Danes just relax – giving time for mindfulness.

“The Danes focus on the small things that really matter, including spending quality time with friends and family” 27

: Jeff Forshaw and Brian Cox :

GUIDE TO THE COSMOS

Part I of IV

THE UNIVERSAL FABRIC About this series In this exclusive four-part series, physicists Jeff Forshaw and Brian Cox introduce us to the biggest ideas in modern physics and cosmology. What is the nature of time? What is everything made from? What happened before the Big Bang, and how will the Universe end? We’ll delve into the deepest questions concerning the very essence of space, time, matter, and reality itself…

ere’s a strange idea: it is impossible to catch up with a beam of light. Light travels at 300 million metres every second, but if you chased after it at 299 million m/s, it would still be receding from you at 300 million m/s, not at the 1 million m/s you might expect (strictly speaking, the light should be travelling though empty space). That crazy-sounding idea comes from Albert Einstein, and is the bedrock of his Special Theory of Relativity. 2

IN EVER

Whethe Y ISSUE: know ho r you want to w how the memor y works , Un or how w iverse formed dinosaur e know what s lo demystif oked like, we y th ideas in e biggest science.

ILLUSTRATIONS: SAM CHIVERS, KATE COPELAND

To understand the cosmos, we first need to get to grips with the nature of space and time. And when we start to do that, some strange ideas emerge…

GUIDE TO THE COSMOS PART 1

zip around fast enough, and so are tricked into thinking time is more constant than it actually is. The fact that a moving clock does not tick as fast as a stationary one is actually quite easy to demonstrate. First, imagine a clock made from two parallel mirrors, between which a particle of light or ‘photon’ bounces back and forth (see ‘The key idea’, right). Imagine you have one of these little clocks in your hand, and that you can watch the particle as it goes up and down, counting the bounces as a way of measuring time. Now imagine that a friend also has one of these clocks, but that she’s moving horizontally. From your point of view, her photon traces out two sides of a triangle as it bounces from one mirror to the other and back again, travelling further during each round trip than the photon in your clock. There’s nothing controversial in what we just said. Here comes the weird bit. Because, according to Einstein, the light bouncing in your friend’s clock is travelling at the same speed as the light in your clock, the light in your friend’s clock must take longer to bounce between the mirrors. In other words, your friend’s clock is running slower than yours. This remarkable conclusion might sound like a special feature of light clocks. But it isn’t… it is a feature of all clocks. To understand why, we need to introduce Einstein’s second crucial idea – an idea first introduced by Galileo Galilei in the early 1600s. IT’S ALL RELATIVE Galileo imagined a ship moving at fixed speed over a calm ocean. Inside this ship, below decks, is a host of “flies, butterflies and other small flying animals”. He noted that, from observations of the creatures made only inside the ship, it would be impossible to tell whether the ship was moving or standing still. The idea that experiments and observations made in a laboratory ‘at rest’ give exactly the same results as those made in a laboratory that’s moving uniformly is called the ‘principle of relativity’, and Einstein followed Galileo in assuming it to be true. According to this principle, if a moving light clock is 2

PHOTO: GETTY , ILLUSTRATION: SAM CHIVERS

“Time does not tick at a steady rate across the Universe – in some places it ticks faster”

2 The implications of Einstein’s idea are enormous. For example, it means that time does not tick at a steady rate across the Universe – in some places it ticks faster than in others, and it becomes possible for people to age at different rates depending on where they are and what they are doing. Perhaps the most dramatic example of this is the ‘twin paradox’, where an astronaut departs from Earth, leaving her twin brother behind. She zips around for a bit in her super-fast spaceship and then lands back on Earth a year later, only to find that many more years have passed back home, and her brother is now an old man. This is exactly the kind of weirdness that must be true if Einstein is right – though we aren’t aware of it in our everyday lives because we can’t

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The key idea

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Glossary

MOTION SLOWS THE PASSAGE OF TIME

LIGHT CLOCK

Imagine a clock made from two parallel mirrors with a photon (particle of light) bouncing between them. If the mirrors are placed the correct distance apart, the photon will take one second to make a round trip between them (A). If the clock is moving horizontally, however, the photon will trace out two sides of a triangle, travelling a greater distance (B). Since the speed of light is constant, the photon will take longer to bounce between the moving mirrors, and – from our point of view – each second on the moving clock will take longer than on the stationary clock.

A type of clock where light bounces between a pair of mirrors. These provide a useful way to think about Einstein’s Special Theory of Relativity, which says a moving clock will run slower than a stationary one.

TWIN PARADOX The puzzle that two identical twins should age at different rates depending on how they move. There’s actually no paradox – Einstein’s Special Theory of Relativity explains why this is true.

NEUTRON STAR These astonishingly dense dead stars have a mass roughly equal to the Sun, but squeezed into the size of a city. Spinning neutron stars emit pulses of radio waves, which can be used by astronomers to test Einstein’s theory of gravity.

PRINCIPLE OF RELATIVITY The idea that there is no way to define ‘at rest’ in any absolute sense. In other words, all motion is relative.

SPACE-TIME Modern physics combines the three dimensions of space and the one dimension of time into this single, four-dimensional entity.

GRAVITATIONAL WAVE The Andromeda galaxy – 50 years away (if you could travel at 99.99999999 per cent of the speed of light)

A moving ripple in the fabric of space-time that causes lengths to change and clocks to tick at different rates as it passes by.

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• • • •

DR ALASTAIR GUNN Astronomer, astrophysicist

DR HELEN SCALES

Marine biologist, writer

ALEXANDRA CHEUNG

Environment/ climate expert

DR CHRISTIAN JARRETT Neuroscientist, writer

DR PETER J BENTLEY

PROF ALICE GREGORY

PROF MARK LORCH

CHARLOTTE CORNEY

EMMA DAVIES

LUIS VILLAZON

DR AARATHI PRASAD

PROF ROBERT MATTHEWS

Computer scientist, author

Heath expert, science writer

Psychologist, sleep expert

Science/tech writer

Chemist, science writer

Biologist, geneticist

Zoo director, conservationist

Physicist, science writer

YOU R QUESTIONS ANSWERED 2017

EDITED BY EMMA BAYLEY

: Y ISSUE IN EVEeRl of doctors,

Our pan s and exper t t scientis nswer your a s r e writ ions. g quest in n r bu

What is the most agile bird? PHOTO: SCIENCE PHOTO LIBRARY

R ACHEL SANCHE Z, MANCHE S TER

Eat your heart out, Tom Cruise, the northern goshawk outstrips your aeronautical tomfoolery

The masters of low-speed aerobatics are the hummingbirds, which can hover with millimetre precision, and fly sideways or backwards. But in the avian Olympics, the slalom medals are all won by woodland raptors such as the northern goshawk. Despite having a wingspan of over a metre, these birds can chase prey at up to 60km/h while weaving through dense forest. LV

33 33

From left to right: preserved penis bone of domestic dog, coatimundi, kinkajou and red fox

Edinburgh of the Seven Seas is the main settlement on Tristan da Cunha

The percentage of doctor visits relating to complaints of being tired all the time, according to a study by Dutch scientists.

Why don’t humans have a penis bone?

CL AIRE RUSSELL , LEICE S TER

The penis bone or ‘baculum’ is common to lots of placental mammals but by no means all of them. It seems to have evolved independently nine times in different mammal lineages but it has also subsequently been lost in many cases. Among primates, humans are the only ones without a baculum, although it is tiny in gorillas and chimpanzees. The baculum allows prolonged penetration and it is normally only present in animals that mate for longer than three minutes. Lengthy sex sessions are an adaptation to maximise the male’s chance of impregnating the female. Humans evolved monogamy as a reproductive strategy, which – along with other social rules – reduces the risk of females mating with rival males. Men can therefore get away with shorter copulation times. LV

I N N UM B E R S

What’s the most remote inhabited place on Earth? JE SSIE BAKER, C ARDIFF

That record normally goes to the Tristan da Cunha islands in the South Atlantic, which are 2,434km from Saint Helena. But they are only the most remote if you consider Tristan da Cunha island itself and Gough Island as part of the same archipelago. The two islands are both inhabited and only 399km apart from each other. Discounting these, the next most remote is Easter Island, which is 2,075km from the nearest other inhabited spot, Pitcairn Island. LV

The number of pups born to a zebra shark called Leonie, despite being separated from her mate for four years.

The number of unique types of forest there are in the Peruvian rainforest, according to new research that mapped chemical signatures in the tree canopy.

Why is Jupiter stripy? OLIVER FLIPPANCE, KENILWORTH

Jupiter’s stripes or ‘bands’ are caused by differences in the chemical composition and temperature of the atmospheric gas. The lightcoloured bands are called ‘zones’ and show regions where the gas is rising. The dark-coloured bands are called ‘belts’ and show where gas is sinking. It used to be thought that the only cause for these bands was the strong atmospheric winds coupled with strong convection cells circulating material between different layers of the atmosphere. However, it is now thought that Jupiter’s moons also play an important role in making Jupiter stripy by tugging on the planet’s atmospheric convection cells. AGu 34

What are the physiological effects of too much g-force? ADHUAY RAO, BY EMAIL

It depends on the direction. An upwards acceleration of about 5g is enough to overwhelm the ability of your heart to pump blood to your brain. This causes oxygen starvation and you will black out within a few seconds. Downward, or negative, g-force is even worse.

The blood pools in your head, your face swells up and your lower eyelids are forced over your eyes. This is called ‘redout’ because all you see is the light shining through your eyelids. At negative 3g, the blood can’t get back to your lungs to re-oxygenate, so you pass out. LV

H OW I T WO R KS

THE ARCABOARD ELECTRIC MOTOR CONTROLLER

ELECTRIC DUCTED FAN

LITHIUM POLYMER BATTERIES

STABILISATION SYSTEM

Unlike some, ahem, ‘hoverboards’ on the market, this one is not powered by wheels and you don’t even need a special track to use it.The 36 fans embedded in the Arcaboard provide a combined 272 horsepower and create almost 2,000N of downward thrust to lift it into the air. The Arcaboard uses a system of gyroscopes to maintain stability in flight.

INTERNAL REINFORCEMENT STRUCTURE

BODY MADE OF COMPOSITE MATERIALS

PROXIMITY SENSORS The whole system synchronises to a smartphone via Bluetooth and can be used in two different modes: in the first mode the rider simply stands on the board and controls the board’s movement with their phone; in the second, just the elevation is controlled by the phone leaving the rider to control the movements of the board by tilting it forwards and backwards.

SPECIFICATIONS SIZE: 145 x 76 x 15cm WEIGHT: 82kg NUMBER OF DUCTED FANS: 36 TOP SPEED: 20km/h (12.5mph) MAXIMUM ALTITUDE: 30cm NOISE LEVEL: 92dB ENDURANCE: 6 mins MAXIMUM RIDER WEIGHT: 110kg

Kuiper Belt Objects are the prime suspects for delivering water to Earth

How old is water? PAUL LESLIE, CHELMSFORD

As Earth was intensely hot following its formation 4.6 billion years ago, little of today’s water is likely to date back that far. Instead, it’s thought to have arrived later, in collisions with objects from elsewhere in the Solar System. Comets were long thought to be the most likely source, but data sent back from the recent Rosetta mission has confirmed suspicions that these ‘dirty snowballs’ contain water with a mix of isotopes different to water found on Earth. So attention has now switched to so-called Kuiper Belt Objects (KBOs) orbiting far beyond Neptune. Studies of these asteroid-like objects have revealed the presence of water, and they are now suspected of having delivered it to Earth when swarms of them smashed into our planet around 3.8 billion years ago. RM

SALLY MORRISON, LEICESTER

Coral bleaching occurs when warmer sea temperatures cause coral to expel the tiny algae that live in their tissues. Without these algae, corals are more susceptible to disease, with impaired growth and reproduction rates. If increased temperatures were shortlived, surviving corals can sometimes regrow their algae within a few months. When bleaching is localised, healthy coral nearby can also help repopulate the area. But in instances of more severe, extensive or repeated bleaching events, or when additional stresses such as pollution or ocean acidification come into play, large swathes of coral may die and recovery can take decades. AC

HEAD TO HEAD

vs COW’S MILK*

ALMOND MILK

(PER 100ML)

CALORIES

<0.1g

SATURATED FAT

0.1g

3.4g

PROTEIN

0.4g

0.1g

SALT

0.13g

trace

VITAMIN D

0.75mcg (7.5% RDA)

CALCIUM

124mg (12% RDA)

120mg (12% RDA)

Almond milk and skimmed cow’s milk are nutritionally very similar. That’s because almond milk is a synthetic product designed to resemble milk. The fat and salt content are virtually identical, and while cow’s milk has * Skimmed

Can coral reefs recover from bleaching?

more protein, it’s still too little to make much difference to your diet. As well as being suitable for lactose-intolerant people, almond milk is slightly healthier though because it contains vitamin D, which cow’s milk does not.

Japan’s largest coral reef, Sekiseishoko, is starting to bleach and die because of higher sea temperatures

Why do our eyes move when we sleep? ELENA HOLDEN, LONDON

PHOTOS: GETTY X2, PRESS ASSOCIATION, SCIENCE PHOTO LIBRARY

Our sleep can be split into two main stages – rapid eye movement (REM) and non-rapid eye movement (NREM) sleep. It is during REM sleep that our eyes dart about. This is also the stage of sleep during which we are most likely to dream. The movement of our eyes is due to specific brain activity that is characteristic of this stage of sleep. Research suggests that eye movements may allow us to change scenes while we are dreaming. Scientists found that the neuronal activity following eye movements during REM sleep resembled that seen when people are shown or asked to remember an image when they are awake. AGr

Why can’t we regrow teeth? PETER RICHARDS, LEAMINGTON SPA

Love our Q&A pages? Follow our Twitter feed @sciencefocusQA

Your baby teeth and adult teeth all began developing before you were even born. Our DNA still contains all the genes that sharks use to grow their endless conveyor belt of replacement teeth, but in humans these genes are deactivated by the 20th week of foetal development. The advantages of keeping the same teeth through adulthood is that they can be securely anchored in the jawbone, which allows us to chew tough plants and grains. LV

How do microbeads affect fish? SUSIE ADAMS, PORTSMOUTH

Plastic microbeads (orange spheres) in a facial scrub

Agrobacterium tumefaciens in action

Can plants get cancer? YASMIN CAINE, CHESHIRE

Yes. Crown galls are a kind of plant cancer, caused by the bacterium Agrobacterium tumefaciens. This causes uncontrolled growth of plant cells around the infection, just like a tumour. Other tumours can be triggered by fungi or physical damage. But plant cells are anchored in place by the cell walls, so plant cancers never spread far or metastasise to other tissues. LV

How do they make spacesuits airtight? ALAN WHITNEY, CAMBRIDGESHIRE

Spacesuits are made of lots of different layers that each protect the astronaut from a different aspect of the outside environment. Only the innermost layer – known as the bladder – is airtight. It’s made of urethane-coated nylon that has machine-welded seams. The gloves are attached using airtight bearings that lock into place but still allow the hand to be rotated. These use precisely machined aluminium and titanium couplings with Teflon coatings for lubrication to prevent the metals coldwelding together in the vacuum of space. Astronauts also breathe pure oxygen so the suit can be inflated at less than a third of normal atmospheric pressure. Even so, spacesuits aren’t perfectly airtight. NASA allows the suits used on the ISS to leak up to 100ml of air per minute. LV 38

There’s no doubt that fish and other aquatic animals eat plastic fragments (under 5mm). These include ‘microbeads’ that are added to toiletries and household products, as well as fibres washed from synthetic clothing. A recent study found three-quarters of flatfish in the River Thames have eaten microplastics. Even deep-sea animals have synthetic fibres in their guts. The impacts of this are complex. Some animals suffer from blocked digestive tracts, leading to starvation. Another concern is poisoning from microplastics coated in toxic chemicals. There’s still much we don’t know about exactly how plastics and toxins accumulate in food webs. HS

Astronauts breathe oxygen before and during a spacewalk to rid their bodies of nitrogen, which could form dangerous bubbles

I N N UM B E R S

The number of years that orangutans can nurse their offspring – the longest time of any wild mammals.

What if Earth had two moons? SIMON TURNER, BRIDGWATER

The consequences of a second moon orbiting the Earth depend on how massive that moon is and how far from the Earth it orbits. The most obvious effect would be that the ocean tides would be altered. Tides could be either smaller or higher and there could be more than two high tides per day. If the gravitational influence of a second moon were extreme, it could lead to phenomenally huge ocean tides (up to a kilometre high) which would also result in frequent tsunamis. It could also lead to enhanced volcanic activity and earthquakes. AGu

The number of seconds (± 7 seconds) that all mammals take to defecate, regardless of size.

The percentage of male sheep that are homosexual.

Why do cats like small spaces? MEG AN JACK SON (AGE 9), ABERG AVENNY

Cats can spend 18 hours a day sleeping. As they are solitary animals, they want a safe hiding place to snooze. But a cat curled in a tiny box, even out in the open, is probably just avoiding your cold floor. Cats are happy in room temperatures around 14°C warmer than is comfortable for humans, and if there isn’t a convenient sunbeam to lie in, they will make do with a cosy shoebox. LV

THE THOUGHT EXPERIMENT

PHOTOS: ALAMY, SCIENCE PHOTO LIBRARY, GETTY X2, NASA ILLUSTRATIONS: RAJA LOCKEY

HOW CAN I SURVIVE A ZOMBIE APOCALYPSE?

1. HEAD FOR THE HILLS

The spread of zombie disease can be modelled using epidemiological simulations. A 2015 study at Cornell University found that cities would be almost completely infected within a week but remote mountains would be untouched after four months. The reproduction ratio (R0) is the average number of new infections that each zombie creates. If R0 is between zero and one, the epidemic will eventually die out.

2. LAY LOW

If the zombies need to eat brains to survive, humanity may be able to simply wait out the crisis. A human brain only contains a maximum of around 2,000 calories, so even the slow and shambling kind of zombie will need to feed every few days just to maintain its metabolism. And any humans that are eaten can’t rise to become new zombies, so the disease would also spread more slowly.

3. FIGHT BACK

Conversely, a 2009 study at the University of Ottawa predicted that even if a cure for the virus is found, zombies will eventually overwhelm the population by infecting us faster than we can be treated. Of the possible scenarios, the only one with a happy ending gave us just 10 days to destroy all the zombies, with a series of increasingly devastating counter-attacks. 39

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