Sciencegate - Michaelmas 2009 by Max Jamilly

Sciencegate - Michaelmas ’09

From the Editor Sciencegate has returned in time for Christmas wth another set of fascinating articles. This issue touches on subjects ranging from surgery to string theory, as well as including the magazine’s first mathematics article: a true testament to the diversity of science. Amid renewed attention towards climate change and a much-anticipated (if disappointing) summit in Copenhagen, this season has seen the LHC resume centre stage along with an un-

usually high-profile series of Nobel Prizes. Science has certainly hit the headlines in the months since Summer, but not solely due to some sudden breakthrough or astonishing result. In fact, there has been fierce debate about the nature of science itself. Scientists nationwide were shocked when David Nutt, the government’s chief advisor on drugs, was asked to resign for stating that “horseriding is more harmful than ecstacy”. It is inevitable, if lamentable, that political intrigue will always prevail over scientific rationale when it comes to policy-making.

Nonetheless, a government which prides itself on an ‘evidence-based approach’ was short-sighted and reckless to refute Nutt’s scientific reasoning in order to justify his forced resignation. A government should, of course, be free to ignore scientific advice. To contradict it without reason, though, is far worse: we have only to remember the disastrous Bush administration to see the result when a government fashions its own reality. Science needs politics to survive; it is time for politicians to realise that they, too, would be lost without science.

In this Issue

Articles

Progress has been slow in the fight bio against the ultimate serial killer: malaria. On p.6,Charlotte Pelekanou glimpses hope on the horizon. In some senses, Colombia has too much to offer. On p.8, Michael Farfan gives an insider’s perspective on a nation’s drug problem. No-one enjoys surgery. As Douglas Howick explains on p.16, the horror of scalpels and syringes could now be history. ‘Identical’ twins are confusing enough as it is, but why are they rarely carbon copies? Max Davidson has the answer on p.11 - with a little help from the Tullochs.

Mr Smith discovers that there’s more to academics than research and that physicists can be superstars (of a sort!). Turn to p.12 for the full interview with Jim AlKhalili. Quarks, bosons, sleptons - what will particle physics suggest next? As the LHC starts for its second time, turn to p.4, where Jamie Worthington hails physicists’ prodigal son: string theory. They sit humbly in our computers and spin wildly in power stations. Shevket Shevket explains the magic of magnets on p.17.

The editor would particularly like to thank Dr Edwards for his help in producing this magazine, and is, as always, indebted to all contributors – without whom would be no Sciencegate. Thanks to Zack Wellin for his cover design (graphic from scienceblogs.com). All contributions are welcome! Please feel free to speak to the editor or send an email to sciencegate@gmail.com. Enjoy the magazine and the Christmas holidays, Max Jamilly

Regulars Where better to build the world’s first zero-energy building than China? Nick Hooton gives you the guided tour on p.7.

Drinking Coke is so passé. Marvel at the power of the atmoshere and make Aladin jealous with Do try this at Home on p.7.

Anyone can point and shoot, but let Terence Ma turn you into a master photographer on p18.

Google may be godlike, but there is more to search engines than blue links and boring pictures. Find the search-engine special of Websites of the Issue on p.17.

Sciencegate enters a new era with its first maths mathematics article. You’ll never look at a horoscope in the same way again: Ed Steele debunks the myth of the coincidence on p.10.

Ding dong merrily on high! On the back cover, the legendary Last Call brings you the latest fix of gadgets, puzzles, and all things scientific.

Sciencegate - Michaelmas ’09

News

From the Nobel to the IgNobel, science news has it all PRIZES GALORE - Last October saw the naming of another set of Nobel Laureates, despite widespread calls for the introduction of new prizes. The 100th prize in physiology or medicine went to three US scientists who discovered telomerase, an enzyme which tidies up and protects the ends of chromosomes. Just outside the nucleus, the chemistry prize was awarded to the scientists (one British!) who used X-ray crystallography to deduce the structure of the protein factories found in every cell – ribosomes. Lastly, the physics prize went to the inventors of optic fibres and CCD chips (see p.18). Meanwhile, a whole host of acheivements, no less academic but slightly more obscure, was celebrated at the IgNobel Awards. From bras that turn into gasmasks to the physics of why pregnant women don’t tip over, to beer bottles and the merits of naming dairy cows, the winner of the mathematics prize deserves special mention: the governor of Zimbabwe’s Reserve Bank, who brought the world’s first hundred-trillion-dollar notes into circulation.

STRIKE TWO - The £6bn Large Hadron Collider (LHC) at CERN in Switzerland has been switched on once again. Just nine days after starting in September 2008, a tonne of liquid helium leaked into the collider tunnel and researchers had to endure 14 months’ repairs. As physicists worldwide look forward to ground-breaking discoveries, CERN director-general Rob Heuer celebrated his machine’s clean bill of health: “It’s great to see beams circulating in the LHC again. We’ve still got some way to go before physics can begin, but with this milestone we’re well on the way.” What’s more, engineers insist that the added year has given them time to smooth over problems in the LHC’s software. So, fingers crossed: the Higgs Boson may have just come one step closer to reality. ANOTHER DAMP SQUIB - All eyes were trained on the moon last October for Nasa’s “Moon bombing”. This was no science fiction escapade: by sending the Lunar Crater Observation and Sensing Satellite (LCROSS) hurtling towards a crater near one of the Moon’s poles, Nasa hoped to throw up an enormous plume of débris. A second impactor was to follow the first down, scanning the plume for water. But, thanks to (surprise, surprise) some calculation errors, the impact turned out to be less than spectacular – the plume Our was barely visible from mistake! Earth. While amateur astronomers swallowed We apologise for two insobs of disappointment, accuracies in last issue’s article entitled Whatever it soon turned out that happened to CERN. To data from thermal imag- set the record straight, ing cameras were actu- construction costs for the ally quite promising. Now, LHC were over budget by around 30% (not 400%). Nasa is certain that the We said that ‘CERN was lunar soil contains not footing a £1bn repair bill’ only cheese, but consid- after the breakdown of the erable quantities of water, LHC in September 2008. This cost of the repairs too. © www.engineering.purdue.edu was actually £18mn. 3

Sciencegate - Michaelmas ’09

Are Strings the Thing? Jamie Worthington Since the dawn of scientific intrigue and discovery, man has sought to answer the question: “How does the universe work?” In the early 20th century, two theories were born which came very close to answering this central question: quantum mechanics and relativity. There is just one problem: the two theories are incompatible. And so the search continued. However, many finally believe that a theory of everything has been discovered, and it may be the most mathematically elegant theory of all time: superstring theory.

field was responsible for gravitation. He explained that matter in the universe curved the space-time continuum like a marble on a rubber sheet curves the surface around it. This curvature causes attractions between things with mass: just as another marble placed on the rubber sheet would roll towards the first, so does matter near other matter “roll” (not literally, of course) towards it. The different strengths of gravity are caused by different amounts of matter – a large mass creates a large

moved, general relativity could explain why. All the same, the theory gave us no clue as to the fundamental constituents of the universe. There was another theory for that. Quantum mechanics, prize theory of many distinguished physicists and often called the ‘most successful theory of all time’, gave excellent descriptions of the behaviour of matter at an atomic and subatomic scale. By ‘quantizing’ matter and energy into particles (e.g. the electron, proton, photon) and formulating laws

theory of matter at small scales – chemists would certainly be at a loss to explain chemical reactions without the knowledge of electron orbitals derived from quantum mechanics.

curvature and a smaller mass creates a smaller curvature.

for how particles behave, scientists were able accurately to explain what “things” are made of and to predict how they would react to different conditions. Quantum mechanics has become the fundamental

nitely dense singularities – very small and yet massive) they found that the two theories broke down in combination. In fact, if you make the calculations (which is not light work!), the entity of time is actually

So, quantum mechanics is brilliant at describing small things and general relativity is fantastic for describing massive things. The way to make a “Theory of Everything” is to combine the two, right? Wrong. When physicists tried to study black holes (infi-

Einstein’s theory of relativity is conventionally broken down into special relativity and general relativity – the latter being the more innovative and astounding of the two. After his ground-breaking paper “Special Relativity” in 1905, Einstein wanted to incorporate Newton’s incomplete theory of gravitation into a more general relativistic theory. In 1905, after eight years of research, Einstein gave a presentation on his theory of General Relativity at the Prussian Academy of Sciences. He postulated that, throughout the universe, an all-pervading field was present – a field which he called “the space-time continuum”. This was a four dimensional combination of space and time, the four dimensions being length (right and left), width (forward and backward), height (up and down) and time. Einstein stated that this 4

General relativity perfectly described the movement of planets and galaxies. If something was big and

Sciencegate - Michaelmas ’09

lost entirely – so the two are obviously incompatible. This was highly problematic because both theories described their own areas almost perfectly. Which one was more correct? It was largely agreed that quantum mechanics was likely to be more accurate, even though it was not the most aesthetically appealing of the two. Physicists set out to create a quantum theory of gravity but it soon became apparent that this was a far harder task than any had previously believed. Eventually, though, they did come up with one particular theory that made predictions to startle even the eccentric Albert Einstein. Superstring theory, sometimes called M-theory or simply string theory, is a potential “Theory of Everything” which states that everything in the universe is composed of tiny vibrating strands of energy called “strings”. According to string physicists, just as the different vibrations of a violin string create different notes, so do different vibrations of strings create different particles. The problem with string theory is that there are many different formulations – in fact, more than a centillion (one with three hundred and three zeroes after it). Of course, we cannot possibly test them all and must narrow down the search in other ways, but physicists have yet to come up with these. String theory is often considered a theory of almost mythical complexity. This is because of its heavy reliance on mathematics and some of the astounding predictions it makes. One of these predictions

is the existence of eleven dimensions: Einstein’s four as well as seven extra spatial ones! This may seem strange and almost blatantly incorrect as we can only experience four

This explains why we cannot experience any of the other dimensions: because we are made of, and can only experience, particles attached to our brane. Moreover, as the

rolled up tightly around the dimensions we can see. Simply put, we are just too big to see them. Think of looking at a power cable from a long distance – it would simply look like a one dimensional line. But, if you were an ant crawling along that cable, you would experience all three dimensions of it. In the same way, we are not small enough to experience the seven other dimensions that string theory predicts. If you aren’t a theoretical physicist, then chances are that the most baffling aspect of string theory will be supersymmetry, one of the theory’s most mathematically abstract aspects.

The path of a radio-wave through space-time, curved by the mass of the Sun

dimensions. However, there are explanations as to how this could be true: two different explanations relate to the principal different “schools” of string theory. The first explanation relates to the string theory model where strings can either be closed and independent or open and “branedependent”. This model hypothesises that our universe is a four dimensional brane (“brane” being the terminology used in string theory to describe a dimensional object) drifting through a seven dimensional bulk. All the matter in the universe consists of open strings with either end attached to our 4D brane; even photons (light particles) would not be able to enter the bulk.

hypothetical particle to carry the force of gravity would be a closed string and could, therefore, drift away from our brane into the bulk, this model also gives an explanation as to why gravity is such a weak force (think of the electromagnetic repulsion between our feet and the ground, which is enough to counteract the gravitational pull of the entire earth). Interestingly, string physicists who support this postulate believe there to be other branes (other universes) floating around the bulk too and think that a possible cause of the Big Bang was the energy created due to the collision of our brane with another. The other explanation describes the seven invisible dimensions as being

Supersymmetry (SUSY for short) states that for every fermion (e.g., the electron) there is a corresponding supersymmetric boson (e.g., the selectron) with the same properties and mass. SUSY is particularly important because, if CERN succeeds in creating supersymmetric particles, string theory will be an even more viable option for a Theory of Everything, proving many of its contenders to be incorrect. So theoretical physics is at an exciting junction with an almost limitless number of roads opening out ahead. Physicists are constantly trying to find new ways to narrow down the number of possible options for a Theory of Everything – some of the greatest minds of our generation will devote themselves to the very same quest. Join in the search and test your “brane” to its limits! sg 5

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The Future of Malaria

Charlotte Pelekanou It is estimated that malaria kills nearly 1 million people worldwide every year. One child dies from malaria every 30 seconds. Half the world’s population is at risk from malaria and, as global warming looms on the horizon, this figure seems set to rise. A hotter climate could enable malarial mosquitoes to survive in areas further away from the equator. But what is malaria’s true future? The use of insecticides has been – and still is – a big issue when tackling the spread of malaria. In the 1950s, a new insecticide called DDT seemed a way to eradicate mosquitoes from tropical areas. Intensive spraying of DDT in homes and schools, lakes and forests, would permanently solve the malaria problem – or so it seemed. The World Health Organisation (WHO) initiated a malaria eradication programme in 1955 and infections fell dramatically but, by 1969, the programme failed. Populations of DDT-resistant mosquitoes swelled and cases of infection bounced back to their former levels. At present, the most reliable way to prevent malaria is to use antimalarial drugs. These stop the development of the malarial parasite once it has entered the human body. However, resistance to some antimalarials, such as mefloquine (sold as Lariam), has already been evolved. The Plasmodium parasite responsible for malaria has a complex life cycle, including a phase in human red blood cells, so there is currently no 6

licenced vaccine to prevent the disease.

infection was reduced by 53%.

One of the UN’s Millennium Development Goals is “to halt and begin to reverse the spread of malaria by 2015”. UN scientists intend to achieve this aim by reducing poverty and improving education about disease prevention. For example, simple strategies can have a major effect – by promoting bednets impregnated with insecticides, fewer people are bitten by mosquitoes. However, around 40% of the population of Sub-Saharan Africa still subsists on incomes of less than $1 a day, making malaria prevention techniques unaffordable. High levels of malnutrition make fighting the disease even harder.

How would a malaria vaccine work? There are three key types of disease prevention. A so-called ‘pre-erythrocytic’ vaccine would prevent Plasmodium from attacking the liver in the early stages of infection. The blood-stage vaccination targets the parasite at the point of rapid replication in the red blood cells. This second type of vaccine merely reduces the severity of an infection, rather than preventing it altogether. Finally, a transmission-blocking vaccine targets not the human but Plasmodium’s

Malarial mosquitoes cause over 1mn deaths every year.

Despite many difficulties, the pharmaceutical company GlaxoSmithKlein (GSK) is in the process of developing a malaria vaccine. At the moment, GSK is in phase III clinical trials (the final stage, with samples of thousands of people). Fortunately, the vaccine appears to demonstrate promising safety and effectiveness: GSK reports that, in Phase II trials, the risk of a malaria

vector, the mosquito. Once the parasite enters a mosquito while the mosquito takes a blood meal from an infected person, the transmission-blocking vaccine seeks to prevent the parasite from maturing. This would limit the spread of infection but not prevent it or reduce the symptoms of the disease – if parasites did mature and the mosquito subsequently infected a healthy person,

the results of that infection would be as severe as normal. The use of slow-acting insecticides is another possible method being developed for the eradication of malaria. Normally, the WHO recommends fastacting insecticides to control the spread of malaria, but this leads inevitably to insecticide resistance. However, using a slow-killing insecticide could reduce the selection pressure that causes resistance to evolve, by killing the older mosquitoes that have already laid eggs, but are not old enough for the malarial parasite to have matured inside them. Therefore, the transmission of malaria is prevented. The insecticide story does not end there. One biologist is already researching a means of combating the spread of dengue fever (another mosquito-vectored disease) by enlisting the help of adult mosquitoes to kill young ones. Instead of using a spray insecticide, a powder is used which sticks to the bodies of the adults – without harming them. The adult mosquitoes then spread this powder to multiple breeding sites. This insecticide kills the larvae of the mosquito. When tested, the powder killed around 95% of the larvae at each breeding site. In the future, the same technique may be applied to malaria. Malaria may remain one of Nature’s greatest killers, but it is also among science’s greatest challenges. sg

Sciencegate - Michaelmas ’09

Pearl River: Project Zero-Energy Nick Hooton Building the world’s most energy-efficient skyscraper is no mean feat. But with the Pearl River Tower, architectural engineering and design firm Skidmore, Owings & Merrill claims to have done just that. Plans for the 300m-plus tower, which will be over seventy storeys high, were presented in Guangzhou, China, in 2005. Guangzhou borders Dongtan, China’s first ‘zero-emission city’ which was meant to be completed by 2010 but seems to have stalled. Designed by architect Gordon Gill, the Pearl River Tower will incorporate the latest in sustainable energy technology, with the ultimate aim of producing more energy than it consumes. If successful, the Pearl River Tower will become the world’s first energy-independent high-rise structure and undeniably one of the world’s most sustainable buildings. Almost all possible avenues for energy production have been exhaustively explored, the most innovative and evident being the structure’s ability to harness wind power.

Do try this at Home! Science is all about getting physical. When it comes to exciting experiments, there’s nothing like the real thing – so don your lab coat and have a go. #91 – ‘Genie in a Bottle’ You’ll be the light of the party when you take out a

The building is split into three distinct sections. Between these sections wind is guided through a pair of openings. The wind then powers turbines, generating energy for the building’s main utilities: ventilation, heating and air-conditioning. These generators are said to produce fifteen times more energy than a free-standing turbine because the funneling design increases wind speed by up to 2.5 times. It also provides structural relief, allowing wind to pass through the building instead of causing it to sway. In addition, natural light will be allowed to flood into the 2.3 million square feet of office space. Further to the harnessing of wind power, the building is designed to include the latest technology for collecting rainwater, humidity and solar power, which should be extremely beneficial in the hot and humid conditions of Guangzhou. Scheduled for completion in 2010, and soon to house the China National Tobacco Corporation, there has been controversy as to who deserves credit for the design, with two different architectural glass bottle with a whole egg inside. This effect has countless uses, but we have yet to work them out. How? This experiment takes considerable time and patience, and frequently more than one attempt, but the result is worth it. Start with a normal (empty) wide-mouthed glass bottle, some vegetable oil, and a fresh egg. 1. Hard-boil the egg by immersing in boiling water for eight minutes.

firms including it as part of their profiles. Despite this confusion, Skidmore, Owings & Merrill is undeniably the driving engineering force behind the project – the same firm behind other high-profile, high-rise buildings including the Sears tower in Chicago and the future One World Trade Centre in Lower Manhattan. The project’s main architect, Gordon Gill, says of the sustainable pedigree of the structure,:“It is like pulling on a thread – everything is connected in some way. We definitely sought to utilise proven technologies; what’s unique is that we’re assembling them symbiotically and gaining from the interrelationships. That’s the beautiful thing about the project, really.”

incentives from China’s Ministry of Construction and a long-term commitment from the tower’s occupants – has led to a design, which, if it can achieve its environmental targets, may just set the standard for all engineering projects to come. sg

The brief for the Pearl River Tower did not demand a zero-energy building, but a combination of factors – such as strong sustainability 2. After the egg has cooled (even if you’re really excited, don’t burn yourself), gently remove its shell. 3. (Instead of steps 1 and 2, you can soak the fresh egg in vinegar for a few days until its shell is soft.) 4. Carefully drop three lit matches into the glass bottle. 5. After a few seconds, place on the bottleneck with its pointed end downwards. 6. As the matches go out, the egg is forced intact into the bottle.

Why? When you heat the bottle, the air it contains expands, reducing pressure. When the matches go out, the air contracts again and pressure inside the bottle falls below atmospheric pressure. The egg seals the bottle, preventing air from entering to equalise the pressure, so the pressure of all the surrounding air forces the egg into the bottle. Be careful! 7

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Colombia kicks the Habit

Michael Farfan Colombian drug traffickers have found a new way to increase the volume of their illegal cocaine exports: by mixing cocaine with another drug called Levamisole, which is used to treat worm infestations in animals and some

deaths and hospitalised a further 100 drug users. On top of this, there have been a number of related deaths in New Mexico and Canada. “The alert today is that cocaine is being exported contaminated with pharmaceutical substances, which can

“Mano firme, corazón grande” - President Alvaro Uribe promises to take a tough stance on drug exports

forms of human cancer. Drug cartels source Levamisole legally from pharmaceutical companies – they buy it in bulk in Colombian cities like Bogotá, Medellin and Cali, then transport it to rural areas where the cocaine is manufactured. US health authorities were on the alert earlier this year after the deadly mixture caused three 8

cause health problems to those who take it,” warns a spokesman from the Colombian Antidrugs Initiative (DNE): “Levamisole works in the nerve cells, and when combined with cocaine results in a fatal stimulus in the central nervous system and a number of receptors in the brain.” Even without the addition of other chemical

substances, an overdose of cocaine spells disaster for the body. From abnormal electrical activity in the heart known as cardiac arrythmia to elevation of blood pressure, the effects are severe. Ultimately, cocaine can lead to death from respiratory failure, a stroke, brain haemorrhage, or heart failure. Emergency treatment usually involves administering a sedative such as Valium to lower the heart rate and blood pressure, physically cooling down the person’s body (using ice or cold blankets) and using paracetamol to treat possible hyperthermia (heat-shock) from increased muscle activity. Forensic studies in the U.S. and Europe have confirmed that cocaine is already cut with Levimasole when it leaves Colombia. The drug is dispatched by the mafia ‘crystallisers’ mixed with up to 20% Levimasole (meaning that for every kilo of cocaine there are almost 200 grams of antibiotic). The ratio is then increased still further when the tainted cocaine exchanges hands: when finally sold by a dealer, there may only be 40% cocaine. In the past, the mafia has laced cocaine with other substances like talcum powder, sugar, and local anaesthetics. Insufflation, better known as “snorting,” is the commonest way of taking powdered cocaine because the drug is quickly absorbed across the mucous membranes and into the sinuses. When impure cocaine is snorted, the

cocktail goes straight to the person’s brain – often with deadly results. The ‘high’ users experience from cocaine is due to increased dopamine and serotonin levels in the ‘pleasure center’ of the brain (the ‘nucleus accumbens’). This feeling can last from about 20 minutes to several hours, depending upon the dosage and purity of the cocaine. But alas, ‘all “good” things must come to an end’, and the high will eventually stop as the cocaine is metabolised by the body into other substances. What follows is the ‘crash’: a feeling of depression after the initial high. Crashes after chronic use can be accompanied by muscle spasms, body weakness, headaches and dizziness. As if that wasn’t bad enough, with excessive use, the drug can cause chronic side effects like itching, hallucinations, and paranoid delusions. So to prevent the drug’s circulation, Colombian police, army and security forces have launched a crackdown on the narcotics trade, promising to help countries like the US in their uphill struggle against Colombian cocaine smuggling across the southern US border. The US backed the Colombian government’s antinarcotics efforts with $7 million in aid. The campaign against the drugs trade has been waged not only in the countryside, where cocaine is grown and processed, but also within the country’s corrupt government and

Sciencegate - Michaelmas ’09

armed forces. Four hundred judges accused of improperly handling narcotics cases have been removed, as well as 280 members of the national police force who supposedly accepted bribes from the Colombian drug-lords. Internationally, tougher customs laws are being imposed to stop cultivation abroad. Even the leaves of the coca plant, which are used to make cocaine, have strict restrictions attached to them. Most countries’ laws don’t distinguish between a coca leaf and cocaine, so the possession of a coca leaf is illegal.

In the Colombian city of Bogotá, however, we can find a small silver lining in the narcotics story. The local government has recently allowed indigenous coca farmers to sell coca-leaf products (excluding cocaine, of course). The initiative aids tribes like the Nasa, who have grown the plant for years and believe it to be sacred. This, ironically, is one of the few successful income opportunities possessed by dimin-

ishing tribes like the Nasa in modern-day South America. When people think about Colombia, the first association they unfortunately make is with a white powder. The illegal drugs trade has detrimental effects on the country’s economy, citizens and on users across the world. Colombia’s president, Alvaro Uribe, stressed that even international

stability is endangered by the drugs trade when he described how the terrorist group FARC benefits from their involvement: “They find support and recruits among the peasants who cultivate and harvest the drug crops.” To most Colombians, it is tragic that a ‘recreational’ drug helps to fund an unending civil war, while their “basic dream is to have a secure nation… without hatred”. sg Drugs: the root of Colombia’s problems

Sciencegate - Michaelmas ’09

How unlikely are Coincidences?

maths Ed Steele ‘What a coincidence!’ you exclaim, meeting an old friend on the same carriage of the same train on the Northern Line. But how unexpected was it really? Could it be said that, given the number of times you didn’t bump into anyone at all and your journey passed without incident, you were probably going to see someone you knew sooner or later? Indeed, the probabilities match up. The word ‘coincidence’ is frequently thrown around. The Oxford English Dictionary defines a coincidence as ‘a remarkable concurrence of events or circumstances without apparent causal connection’. Nonetheless, for any probability or so-called ‘chance’, if the possible situation occurs a large number of times, it becomes more and more likely that a coincidence will take place. In fact, there becomes a point where it would be unbelievably unlikely for a coincidence not to happen! To take a famous example, consider a class of 23 students. It is more likely than not that somewhere in that class, two students will share a birthday. If this is noticed in a class, most will cry out in amazement – but not the mathematicians. They nod sagely to each other, calculating that there was a 50.7% chance of two people from that class having the same birthday. Certainly, many of you are skeptical of this result, so what follows is a brief derivation. 10

The number of ways in which 5 dates can be chosen (allowing for repetitions) is 3655 because you have 365 options for your first choice, after which you still have 365 options for your second choice, and so on. Of these 3655 ways, however, only (365 x 364 x 363 x 362 x 361) are such that no two of the dates are the same; any of the 365 days can be chosen first, but only the remaining 364 can be chosen second, and so on. Therefore, the probability that five people, chosen at random, will have no birthday in common is equal to (365 x 364 x 363 x 362 x 361) / 3655. If we subtract this probability from 1, we find the probability that at least two of the five people do have a birthday in common. (To understand this, imagine you are competing in a race with four other people of the same ability as you: the probability of you winning is 1/5; the probability of you not winning is 4/5.) For the birthday problem, a similar calculation using 23 rather than 5 gives a probability of over ½ that at least two of the 23 people will share a birthday. This reasoning applies to larger situations as well. For instance, whenever a disaster occurs, we hear stories of people claiming to have had premonitions of it in their sleep the night before; historically, many have claimed that powerful prophesies came to them in dreams. To this, mathematicians say, ‘Why not?’ With so many major world events occurring, and so many

people sleeping and dreaming, there is an enormous number of opportunities for people to happen to dream about a stock-market crash, say, on a night before one occurs. Let us take this idea slightly further. Assume the probability that a particular dream matches some sequence of events in real life to be 1 in 10,000. This is a pretty unlikely occurrence, and means that the chances of a non-predictive dream are an overwhelming 9,999 out of 10,000. Also assume that whether or not a dream matches an experience one day is independent of whether another dream matches an experience some other

day. Therefore the probability of having ‘n’ straight nights of non-predictive dreams is (9,999/10,000) n; for a year’s worth of non-matching dreams, the probability is (9,999/10,000)365. Since this is equal to about 0.964, we can conclude that about 96.4% of the people who dream every night will have only nonmatching dreams during a one-year span. But that means that about 3.6% of the people who dream every night will have a predictive dream. 3.6% is not such a small

fraction; it translates into millions of apparently pre-cognitive dreams every year. Even if we change the probability to one in a million for such a predictive dream, and we assume that people don’t dream every night, many people with apparent psychic powers will still turn up annually. There’s no need to invoke any mystical abilities; the common incidence of ‘predictive’ dreams requires no transcendental explanation. For one person and one event, the odds are very long, but with nations of dreamers you can safely bet that ten or twenty of them will happen to have an apparently prescient dream on the eve of the next calamity. We can see this type of phenomenon in everyday life whenever we watch a lottery draw. The chance of any one person winning the jackpot is minimal, and yet most weeks someone does win. The large number of players compensates for the unlikelihood of any one given player winning. Although coincidences seem amazing and extraordinary when they occur, it is usually very likely that they will occur at some point; it is only unlikely that they should take place at a particular time. So next time you’re told about a psychic or take the same flight as a friend, think twice before calling it an impossible coincidence. Ask yourself, ‘How unlikely was it really?’ sg

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The Trouble with Twins

Max Davidson

Have you ever wondered why identical twins are never really identical? After all, both came from a single fertilised egg – so they supposedly share the same sets of genes from their mother and father. Identical twins are described as monozygotic, because a single zygote (fertilised egg) divided into two embryos to form two babies. Nonidentical twins are dizygotic, since two eggs with different genomes, having been unusually implanted in the uterus lining at the same time, are fertilised by two genetically different sperm. It makes sense that dizygotic twins can look and act so differently, since they have a very different genetic make-up to control their physical and behavioural development. But what about monozygotic twins – shouldn’t they be identical in every way? While most twins grow up in the same home environment, there are many external circumstances that create differences in monozygotic children’s appearances, personalities, and interests. As the twins approach their teenage years, they may even try to develop dissimilar qualities in order to establish individual identities. However, there is a more deep-rooted cause. In fact, the answer appears to lie in epigenetics, a newly-emerging field of biology which (according to one definition, for there are many) explores the non-genetic factors controlling the development of an organism. These factors could be deter-

mined by a foetus’ microclimate in the womb. Epigenetic changes arise due to differences in the way twins’ genes are expressed in their bodies. Just as a single set of blueprints could be interpreted in several ways to make many different buildings, so one genotype (set of genes) can lead to many phenotypes (sets of physical characteristics). Similarly, even though there is no change to the DNA sequence itself, environmental factors can stimulate chemical markers such as methyl groups to attach to genes. These epimarkers may cause a gene to express a particular protein more, less or not at all. Effectively, chromatin (the storage form of DNA in cell nuclei) is remodelled. Even the way in which DNA is stored can change, affecting the phenotype of an organism. In medicine, epigenetics is only now being given serious consideration. Until studies began irrefutably to point to environmental changes to the genome, many biologists denied their existence – still now, epigenetics seems at odds with traditional genetics, which holds that genes can affect the phenotype but never viceversa. Today, however, there is continuous research into epigenetics. There appear to be specific genetic regions that coincide with

specific diseases. Many believe that we could use epigenetics to locate and, one day, to control the exact genes responsible for illnesses such as asthma, psoriasis, Angelman syndrome and Prader-Willi syndrome. The latter two are normal genetic diseases but are caused by the inactivation of one gene on chromosome 15. More interestingly, they are examples of genomic imprinting, whereby only the version inherited from a single parent is expressed. Before 2008, it was accepted that any differences between identical twins boiled down to environmental influences: to nurture, regardless of whether this had an epigenetic effect or not. Now there is evidence to suggest that in fact, though their DNA is very similar,

there are actually differences in twins’ genetic codes. Normally people carry two copies of every gene, one allele inherited from each parent. However, there are sites of ‘genetic divergence’ where each twin has different numbers of versions of a gene (or copy number variants), ranging from zero to over fourteen copies. In one study, one twin that was missing copies of a particular gene on one chromosome suffered from leukaemia, while the other, whose gene functioned, did not. So monozygotic twins are not identical because throughout their growth and development, the environment changes the way in which their genes are expressed. Even in identical environments, however, epigenetic differences could arise between the twins as ‘epimutations’. If we can learn to harness these, the implications for genetics and medicine would be enormous. sg

Iain (left) and Angus Tulloch, Highgate’s very own non-identical identical twins.

Sciencegate - Michaelmas ’09

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Interview: Jim Al-Khalili

Mr David Smith Jim Al-Khalili OBE is one of the best-known figures in British science. Now a professor of physics and chair of Pulic Engagement in Science at the University of Surrey, he has written three books and frequently appears on television. David Smith, Highgate’s head of physics, talked to Jim last September about broadcasting, academia, and his passion for physics. This article appears in the November edition of Physics Education, published by the Institute of Physics, and is reproduced here with Mr Smith’s kind permission.

When did you realise that you were good at outreach? Well, I chose a career in academia because that that was what I really wanted to do. I managed to get some teaching as a young postdoc before beginning my lectureship at Surrey, just to sample what it was like, and enjoyed it. Communicating science to the wider public was something that came about almost by accident and grew gradually – I certainly didn’t start with a burning ambition to be in front of the camera! I began by giving talks at local schools and progressed to giving the odd radio interview or writing a magazine article. Things slowly took off from there – but every step relied on having achieved the previous one. Then I was invited to give the Institute of Physics UK Schools Lecture Series in 1997 and on the 12

back of that I was commissioned by the Institute of Physics to write my first book: Black Holes, Wormholes and Time Machines. I’d accumulated a lot of information and great stories on cosmology, and although that wasn’t my research area I had found that it’s a really great hook for school kids. And once you’ve got one book under your belt it becomes easier to approach a publisher or an agent with another book.Quantum: A Guide for the Perplexed was burning inside me. Getting involved with TV was again something that came by accident. I did a little bit as a contributer and it seemed to go well – I felt comfortable in front of camera. One thing led to another and I’ve now got a nice fifty/ fifty balance between the academic life of teaching and research and the outreach involving broadcasting and writing. I would like to keep it that way – but it took me a couple of years to get the tension right. This last year, 2009, has been ridiculously busy in terms of the outreach and broadcasting – I’ve done three TV series for the BBC and Channel 4, all to be screened in 2010, a BBC radio series, and I’ve written the first draft of a new book on the history of science. But now that’s all done I’m back to academia and looking forward to getting stuck back into my research and my teaching.

Does the university approve? I hope so! Not all universities feel the same about

outreach, but things are changing quickly and Surrey happens to be very progressive in that sense. Surrey sees the value of science communication as an important fourth strand to add to the other duties of an academic, which are traditionally teaching, research and administration. When I meet up with my Vice Chancellor, I always get a nice pat on the back for the outreach I’ve done. In a way, I am acting as an ambassador for the university.

Before we go on, tell me about the nuclear halo poster that I passed on the way in. I came back to Surrey after spending two years at University College London researching theoretical nuclear physics. This was, and still is, the largest research group in that discipline in the UK. Until relatively recently, we thought of the atomic nucleus as consisting of protons and neutrons packed tightly together like billiard balls in a bag. But in the late 1980s, it became possible to create beams of short-lived nuclei, in which more and more neutrons had been loaded onto stable nuclei to produce very neutronrich isotopes of elements like helium and lithium. A famous example is helium-6 – an alpha particle with two extra neutrons. The ratio of neutrons to protons is so large that the last two neutrons tend to float around outside the alpha particle, though still much closer of course than the two

electrons. If it wasn’t for quantum mechanics these nuclei wouldn’t exist at all because these neutrons spend most of their time at a distance from the nucleus that is further out than the range of the nuclear force that’s binding them in the first place! What they’re doing is quantum tunnelling, so there is a probability that they’ll be found a long way from the nucleus. You can’t really think of it as billiard balls, but if you could take a snapshot of the He-6 nucleus, the chances are that you’d find two neutrons sitting way outside the alpha particle forming what’s called the neutron halo. It happens with neutrons and not with protons because, by adding extra protons, the electromagnetic repulsion means they are pushed away very quickly and the nucleus falls apart. My most cited paper is on work I carried out with another colleague here at Surrey – we calculated that, because of the halo, the nucleus of lithium-11 was fifty percent larger than anyone had realised, giving it a size almost equal to that of a lead nucleus. We still don’t have any applications for these halo nuclei, but they’re certainly a new species of matter!

Does the initiative for your TV programmes come from you or elsewhere? On the whole, I haven’t had to be proactive

Sciencegate - Michaelmas ’09

– people have come to me. In the case of Atom, a producer contacted me and said that he wanted to do a series about quantum mechanics. He knew I’d written Quantum and that I’d done a little bit of TV work. On the back of Atom, he asked whether I had any other ideas and that’s how Science and Islam came about: because of my cultural background. I’ve just finished filming a sequel to Atom about the chemical elements, an idea that came from the BBC, who were keen for me to do something else after Atom went down so well despite its tough subject matter. So things are bubbling along nicely – Marcus de Sautoy and I are seen as the faces of science on BBC4, which is very nice, while Brian Cox, for example, is seen as the physicist face for Horizon on BBC2. It’s quite flattering to have this little niche, but I don’t plan on moving too far into that field because I want to maintain the balance with academic life.

Do you enjoy filming? I won’t say it’s tedious, but there are long days – you are up at 5 a.m. and put in twelve or thirteen hours, often not counting several hours of travel. That can mean a long time to keep the adrenaline going. After all, I must come across just as enthusiastic in front of camera in the next take as in the last! The novelty has now worn off, I guess, but I still thoroughly enjoy it – I love the passion of looking

through that camera lens and imaging I’m talking to someone sitting on a sofa, saying, ‘This is how the universe works – isn’t it brilliant?’

How is the impact of your programmes judged? Well, certainly by viewing figures. Apart from X-Factor and Strictly Come Dancing, programmes these days don’t have tens of millions of viewers because there are so many channels. Anything on BBC4 with a quarter to half a million viewers is regarded as a success. On that measure, Atom was a huge success, but the post-programme comments online were also gratifying. People wrote things like ‘At last proper science is back on TV!’ and ‘Thank you for broadcasting something that is substantial – we’re not stupid; we just need to be presented the subject in non-technical language!’ That was nice, because the BBC Jim Al-Khalili on set for Science and Islam. When the camera isn’t rolling, Jim works as a teacher and lecturer at the University of Surrey

had taken the plunge not to simplify too dramatically and the au-

dience appreciated it.

I grew up watching things like Jacob Bronowski’s The Ascent of Man, and Brian Cox admits to having been inspired by Carl Sagan. Is there someone who had a similar effecton you?

I think I was more inspired by teachers at school. I had good physics teachers and they really made me conscious that there was this exciting world out there, beyond what we had to learn from our textbooks.

⟶ © www.al-khalili.co.uk

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Interview: Jim Al-Khalili (cont.)

⟶

Mr David Smith

reading around the subject or do you I remember my physics just have a massive teacher, Mr Williams, en- knowledge base? tering the class, shortly after I’d started A-Level physics in 1979 and they had just announced the Nobel Prize for Glashow, Salam and Weinberg. He explained how they were trying to unify the forces of nature – it just seemed so exciting! So I was inspired more by teachers than by TV. At university, popular science writers like Paul Davies and John Gribbin took me out of the curriculum and into the foundations of quantum mechanics – questions like ‘What does it all mean?’. I lapped up those books, and went on to read many of the biographies of some of the pioneers of 20th century physics, such as Bohr and Rutherford.

You are clearly interested in the history of physics... Absolutely. Although I enjoy the maths, the formulas and the problem solving, my enthusiasm for the subject was built around the characters. That’s also true of a lot of people who are scared of the science, but are still interested in the personalities of the people and their thought processes.

You have recently lectured about Copernicus and your blog talks about Galileo; are you continually 14

No, I am a constant steep learning curve! My interest in the history of science used to be very much restricted to the early 20th century and to some extent the 19th. But my broader interest, going back to the Greeks, is something that has really grown in the last two or three years. In fact an interest in history – not just the history of science – is something that I’ve suddenly woken up to in the last few years. I was invited to judge the BBC4 Samuel Johnson Book Prize for non-fiction a few years ago – I was the token scientist on the panel. Consuming dozens and dozens of books over a few months was like an accelerated liberal arts degree – whether it was politics, history or art, I decided there and then that I really had to broaden my horizons.

Which of your recent forays has given you most pleasure? I am very proud of Atom. The Science of Islam was a great experience – the travel-

you going to make a programme together?

ling was fantastic and uncovering some of the stories was a great adventure. Being able to explain really hard concepts like quantum physics to a general audience was fantastic – I didn’t think that would ever happen. And I found it hugely rewarding to have people writing in saying, ‘I loved the way you explained quantum jumps using a multi-storey building.’

We are talking about possibly fliming something similar to Alan and Marcus Go Forth and Multiply, the Horizon programme that Marcus de Sautoy made with comedian Alan Davies on maths. But then Marcus was clearly the brain-box and Alan was the stooge, being taught why maths is such a great thing.

And do you still enjoy teaching? You couldn’t do that with

someone of Stephen Fry’s intellect – the roles would be reversed, for heaven’s sake! But remember that his father was a physicist, so it would not be too far-fetched to put something together along the lines of a Who Do You Think You Are?-type programme. There was that wonderful awardwinning documentary Parallel Worlds, Parallel Lives about Hugh Everett, the father of parallel universes. His son Mark, a lead guitarist in the rock group Eels, tried to come to terms with his dad having been really famous in the physics community for coming up with the idea of parallel universes. So maybe I could take Stephen to visit some of the work that his father did as a physicist in a similar sg way.

Yes! I certainly miss it when I’ve had a period of being away. I do look forward to the students coming back, particularly the new undergraduates. The course I teach, Space, Time & Relativity, is admittedly a crowd-pleaser and is clearly more fun than doing thermodynamics or electronics – certainly as far as the students are concerned. But I get a buzz out of things like deriving E = mc² from first principles, or explaining why nothing can go faster than the speed of light.

You imply on your blog that you are a fan of Stephen Fry. Are

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Sciencegate - Michaelmas ’09

Special: the McCollough Effect Discovered by Celeste McCollough in 1965, the effect which takes her name has been used by scientists ever since to explore the workings of the brain. Like many visual illusions, the effect is simple to produce – what makes it so amazing is that it lasts for several hours. Start by looking at the grid at the bottom of the page. You should see two sets of horizontal lines and two sets of vertical lines, all black-and-white. Now cover up the bottom grid and stare at the two coloured grids for at least three minutes - be patient; it’s worth it! Finally, uncover the bottom grid - does it look any different?

Does the black-and-white grid appear coloured? The vertical lines should be red and the horizontal lines, green. Try turning the page by 90˚. Scientists are still unsure as to what exactly causes this surprising effect. Most agree that it is the result of sensory adaptation, where the brain eventually ‘tunes out’ repetitive stimuli - like when a sweet eventually loses its flavour or, a few seconds after sitting down, you no longer feel the chair beneath you. When your eyes receive the same stimulus for a long time, neural adaptation occurs and produces a ‘positive afterimage’. Everyone knows that staring at a bright light creates a negative afterimage, but there must be more to this effect than fatigued neurones because it is so long-lasting; nonetheless, it may be linked to concentrations of different neurotransmitters in the brain. 15

Sciencegate - Michaelmas ’09

Microbots: the Future of Surgery?

bio Douglas Howick For the last decade or more, medical researchers have posed a question: How might you explore the narrowest arteries in the human brain? This strange idea is not some science-fiction fantasy. It has a genuine application: treating strokes. Strokes are a major cause of brain damage and death, especially in those over 65 but now amongst younger people as well. Strokes are primarily caused by a blood clot in one of the smaller vessels of the brain. This leads to a

build-up of fluid and eventually a blockage or complete rupture. Brain tissue, starved of oxygen and nutrients, quickly dies. Severe loss of brain function can be caused easily and is often permanent - and that’s assuming the patient actually survives. Cutting edge research in an area of previouslysidelined mechanics could provide a more effective treatment of strokes and coronary heart disease. The design of the electric motor has changed little since the 1950s, the focus in electronics over the last 20 years being microchips and nanocircuitry. This sort of technology has advanced rapidly and, meanwhile, appliances have grown smaller and smaller; every year there is a new, “improved,” smaller iPod or mobile ‘phone. Well, now it’s the turn of the humble electric motor to be the centre of ground-breaking research.

Piezoelectricity is generated by special crystals which induce a high voltage when they are stretched or squashed. I don’t blame you if you haven’t heard of the phenomenon! However, piezoelectricity has been around and used for quite some time: it was discovered in 1880 by the Curie brothers. It is used to ignite gas stoves, wind up watches and, now, to power tiny motors of no more than a few micrometers in width. The piezoelectric motor is used in a tiny robot (known, inventively, as a microbot), where it spins a tail much like the bacterial flagellum. This provides enough forward thrust to push the microbot around all of the blood vessels in the body, even against the flow of blood. The microbot itself is 250 micrometers long and about 50 wide, mostly to accomodate the motor. However, it also has a tiny camera and LED lights up front. The bot is controlled remotely by the surgeon

operating and the cameras allow them to see where they are going. In the future, it is hoped that a microbot will be able to penetrate the labyrinth of vessels in the brain, where surgeons twenty years ago could only dream of going. The main aim of the microbot is to replace the catheter, a flexible tube used to reach inside blood vessels. Clearly, catheters have their limitations. They often cause more problems than they solve, being a very cumbersome method of investigation, and make fatal tears in blood vessels. Soon, minute surgical equipment could be attached to the front of a microbot allowing a complete surgery to take place with no major incisions. The result: an easier, more effective and less invasive form of surgery. The microbot is a clear step forward and holds exciting possibilities for the future. The microbot truly takes keyhole surgery to the max. sg

The Proteus piezoelectric nanobot, developed at Monash University in Australia - coming soon to a blood vessel inside you!

izmag.co

Sciencegate - Michaelmas ’09

phys

The Secrets of Attraction

Shevket Halil Shevket From compasses to microphones to the G-Wiz, people use magnets every day, but to most the magnetic field remains a mystery. For centuries, people have investigated the invisible forces between magnets. The best way to begin answering this question is to place two magnets on a table, the south pole and north pole facing each other. Place a sheet of paper on the magnets and pour on some iron filings (or, if you don’t have any iron filings knocking around use paperclips or see the image right). As if by magic, the iron filings will surround the two magnets and form lines between them. This interesting and beautiful pattern is key to explaining how a magnetic field works. Each line, known to physicists as a ‘field line’, can be thought of as a vector. This illuminates some important features:

each other. Field lines are difficult to visualise and still harder to rationalise, but a simple analogy can shed light on the nature of magnetic attraction. Loop an elastic band around your two index fingers, which represent two opposite poles on separate magnets. Of course, the opposite poles attract - in the same way, if you pull

moving away from the centre. There’s more to magnetic fields than rubber bands. Often, a charged particle such as an electron moves through a stationary magnetic field. Back in the days when the flat screen was the stuff of science fiction, this principle was central in CRT (cathode-ray tube) monitors: electrons were fired towards a phosphorescent screen and focused by magnets. It turns out that we can easily quantify the force exerted on a charged particle by a magnetic field, known as the Lorentz force. Consider a particle of charge q (in Coulombs) moving with a velocity v (in m/s) in a magnetic field of strength B (in Tesla). The particle will experience a Lorentz force F = qvB.

This equation is vital for the understanding © www.scienceblogs.com of magnetic fields. It shows that the force Iron filings reveal the shape of the on a particle is proporfield lines around a bar magnet tional to the charge and • The lines always start your fingers apart, the velocity of the particle from the north pole and elastic bend stretches and the field strength. go to the south pole. and tries to force them At any given velocity, a back together. Just as particle will experience • Areas with higher line the band becomes lon- a greater force between density have stronger ger and less curved, so two magnets if there are magnetic fields. do the field lines between more field lines - that is, attracting poles when the if the magnetic field is • The tangent to any field separation distance is stronger. The fundamenline at a given point will increased. tal point to note is that give the direction of the the particle must have a field at that point, but the The reverse situation, charge in order to feel a overall direction along where two like poles force. If q is zero, then any line remains the repel, is harder to recre- so is F. Therefore, if you same - from the ate. Nonetheless, in this stick your finger between north pole to the south case there are two elas- two magnets, no force pole. tic bands: separate sets will be felt. of field lines originating • The lines never cross from each north pole and When it comes to the

Websites of the issue Fed up with Facebook? Tired of Twitter? We don’t blame you. Sciencegate has gone to the darkest corners of Web 2.0 and brought back some of its best-kept secrets. learn.genetics.utah. edu/content/begin/ cells/scale/ Dive into the microscopic universe. Feel at once enormous and insignificant with this slick but simple animation. www.spezify.com Google may be poised to take over the world, but Spezify is close behind. This search engine’s intuitive, visual results are the ideal match for the new generation of touch-based computers. The only danger is that you’ll never want to click through. www.wolframalpha.com Skynet is live. We hate to admit it, but Wolfram Alpha may know just about everything. From history to histology to histograms, ask this ‘knowledge engine’ and ye shall almost certainly receive. This is an alpha release, so don’t be surprised if the next version can hold a conversation or make coffee. Control Wolfram Alpha before it controls you. wonders of magnets, these ideas only scratch the surface. But, next time you see a CRT monitor or save a file on your computer, remember that this is all down to magnetism. sg 17

Sciencegate - Michaelmas ’09

Digital Photography: a Beginner’s Terence Ma In the last issue, Highgate’s resident student photographer introduced us to animal photography. Now, he goes back to basics.

more difficult. If you are a beginner, it is best to start with a basic compact digital camera. Beginner’s compacts have only a few features,

megapixels only give you a rough idea of its quality. You have to see what features the camera has like screen size, zoom, lens quality and image

level, there are several advanced compacts in the market with many more features, such as the option to shoot in Raw or JPEG (I will explain the

So, you want to start taking great photographs? Here’s how. Firstly, you need to choose the right camera. Using a camera which doesn’t suit your needs will only make learning

Instant

Expert How does a digital camera work? The advent of cameras containing charge-coupled devices (CCDs) revolutionised photography. In pre-digital cameras, the lens projected an image onto a light-sensitive layer – the film. In modern, digital cameras, the film is 18

so you should be able to master your camera very quickly. When choosing your camera, don’t fall into the common trap of assuming that the more megapixels your camera has, the better. Your camera’s

stabilisation, then weigh these against disdvantages such as weight and battery life.

difference below).

If, on the other hand, you are at an intermediate stage and want to take photography to the next

Lastly, if you are an advanced photographer, I would recommend buying a digital single-lens reflex (DSLR) camera right away. Especially as your skills progress, there

replaced by a thin layer of silicon deposited on the surface of a CCD chip. The surface of the chip itself is divided into a grid of millions of pixels. Every pixel is really a ‘potential well’ which, like a bucket filling with water, fills with charge when light falls on the photsensitive silicon above it. The charge is ‘poured’ from one bucket to the next and, with some clever circuitry, the intensity of light falling on each

pixel (an analogue value) is converted into a digital value and recorded. Add in some filters above groups of pixels, and you have an image. The modern form of the CCD is the complementary metal oxide superconductor (CMOS), wherein each pixel has its own circuitry for recording a digital light-intensity value. Although cheaper and less power-hungry, the analogue-to-digital conversion

generates even more noise than the original CCD. The solution? A new tpye of image sensor, developed at the Swiss Federal Polytechnic Institute, produces digital values directly at each pixel, meaning much less noise. What’s more, since eliminating the analogue-to-digital conversion circuitry makes each pixel so much smaller, you can forget megapixels: gigapixels are the future.

Sciencegate - Michaelmas ’09

Guide are major differences between DSLR and compacts. In short, DSLR gives you finer control over your camera - from exposure to aperture to whitening - enabling you to be more creative in taking that perfect shot. What is more, with a DSLR, you must buy at least one lens: again the type of lens you choose depends entirely on what type of photography appeals to you. There are different type of lenses such as fixed and zoom; the most common are macro, telephoto and wide angle lenses. The focal length of a lens is the minimum distance of

close-up photography and, compared to other lenses, have the lowest level of distortion. Telephoto lenses have a very long focal length, making them excellent for wildlife or sport photography as the photographer can zoom in very close to the subject. Finally wide angle lenses are for landscape photography, absorbing as much sunlight as possible to make the picture sharper and better. If you are just starting to use a DSLR and don’t know what lens to buy, I would strongly suggest Canon’s 75-300mm f/4-

opinion, Canon’s imagestabilising technology makes their lenses the most reliable; however, many prefer Nikon camera bodies. As a serious photographer, it is vital to understand the difference between shooting Raw image files and using JPEG - don’t let anyone tell you these are the same! There is a distinct difference between Raw and JPEG and most serious photographers choose Raw. Here’s why: Raw files are completely lossless - they don’t remove data to save space. You can then use your

unprocessed Raw image, compression makes the true image quality of a JPEG lower. The more you edit and save, the more data you lose. If you have the right software and are prepared to spend time processing your photographs, taking Raw images allows you to change settings such as white balance and saturation after you have taken your photos - far more alterations are possible than when you shoot on JPEG. Nonetheless, many still use JPEG because it is a convenient format with a low file size.

an object from the camera in order to be in focus. A macro lens usually has a focal length from 50200mm. For a telephoto zoom lens, this normally rises to 70-200mm and for wide angle zoom lenses, the focal length is 16-35mm. Macro lenses are for

5.6 III USM lens to start off or, if your budget is bigger, the Canon 70300mm f/4-5.6 IS USM lens. Again,the decision is yours: like cameras, different lenses suit different personalities. Personally, I use a Canon Eos 40D with Canon 70300mm f/4.5-5.6 DO IS USM lens attached. In my

computer to process Raw files in the same way as a camera to produce the final image. Although JPEG files are much smaller, they are compressed before saving and some data is removed. Naturally, even if a JPEG image seems sharper compared to an

The first steps towards enjoying photography are simple: you need a camera and lens which suit you, backed up by the best file format for you and, most importantly, the will to succeed. I hope this article gives you the inspiration to take pictures for yourself. sg www.terencema.co.uk 19

Sciencegate - Michaelmas ’09

Last Call Mince pies, crackers, Bob Geldoff and Sciencegate - what more could you need for the Christmas holidays?

The Knowledge

Scientists have all the fun. Here is Sciencegate’s pick of what’s hot this season in the world of science.

Technology It looks unassuming, but beneath the sleek curves of Apple’s new Magic Mouse is the same technology that lurks within the iPhone: the mouse’s surface is touch-sensitive, so you can swipe and pinch with stylish ease. Gadget Say goodbye to charger wires. Stick on a small receiver and place your gadget on a Powermat: it will charge as if by magic! Apart from the Powermat’s mains connection, the system is wire-free and works for everything from iPods to ‘phones to cameras. It’s all due to simple magnetic induction (but don’t tell people that).

Software OS Wars: The Empire Strikes Back. Almost immediately after Apple’s release of its new Snow Leopard operating system, Microsoft has released Windows 7. But, never one to miss a party, our old friend Google has announced its own take on the operating system. Chrome will be entirely web-based, optimised for fast loading on netbooks. We are very excited. Vehicle If you’re uncertain what to do with this year’s Christmas money, why not try the world’s first winged civilian submersible? At only $1.5mn, the Super Falcon may be the answer.

Mind-benders The six matches are used to make one triangle. Can you rearrange the matches to make eight triangles?

Can you rearrange three snooker balls to make this triangle point upwards?

Teapot A holds one litre of tea. How much tea does teapot B hold?

Interested in writing for Sciencegate? Speak to the editor or email

sciencegate@gmail.com for ideas. Are we playing God? Maybe. But haven’t we been playing God for 10,000 years? – Dr Enrique Lopez (on genetic modification) 20