She seems to have an invisible touch

Imagine the things you would do if you had Harry Potter’s invisibility cloak. Everyone has had this fantasy, but now it seems that this staple of science fiction from Star Trek to Dr Who may be close to science fact, although it requires a little imagination, and a little faith in some extraordinary mathematics.

Within the last few months, a number of theories for developing cloaking devices have been unveiled. Two recent reports in the magazine Science have described how experimental "metamaterials" can change the way light bends around an object, to create an illusion that we might call a mirage.

Metamaterials are composite materials that are designed to have interesting properties, such as the ability to bend light. They contain microscopic rods or metallic rings that can be tinkered with to interact with light in controllable ways, such as to manipulate how quickly light travels when near particular parts of the material. However, despite our espionage fantasies, any invisibility cloaks made out of the material in the near future would be extremely heavy and thick, and you would not be able to see out of them.

Physicist Ulf Leonhardt, of the University of St Andrews and an author of one of the reports in Science, wrote "Imagine a situation where a medium guides light around a hole in it. The light rays end up behind the object as if they had travelled in a straight line. Any object placed in the hole would be hidden from sight. The medium would create the ultimate optical illusion: invisibility." This is like what happens to water when it runs around the outside of a smooth rock in a river, and occurs in our case here because of refraction - a characteristic of light where it takes the quickest, but not necessarily the shortest, path. We can see refraction by simply dropping a pen in a glass of water and observing that it looks like its bent, when we know its not.
Sir John Pendry of Imperial College London, author of the second report, also predicted that with sufficient funding, the first of these devices could be around within 5 years.

These devices could also be used to hide objects from other electromagnetic waves and even sound. This has obvious Defence applications. David Schurig of Duke University in North Carolina and Pendry’s co-author stated that this Defence goal "would be to conceal an object from discovery by agents using probing or environmental radiation." This is a different method of stealth than modern methods used to hide planes from radars. Current stealth technology revolves around reducing a plane’s "Radar Cross Section". Radars work by sending out electromagnetic radiation, and then detecting when it reflects back off its target. To reduce the amount of radiation that is reflected back by the plane, we can design the plane’s shape such that reflections do not go back in the direction they came, we can make it out of a material that is non-metallic and so less reflective, and we can paint it with paint that absorbs the radiation. But these methods never make a plane entirely invisible to radar. With this new technology, the hope is that the radiation does not even hit the plane in the first place.

Along with the problem of not being able to see out from the inside of such a material, is the fact that the more types of radiation against which that we make the material work – for instance, if the material cloaks against visible light and microwave radar – the more expensive and difficult the material is to produce.

Another recent study comes from Professor Graeme Milton, of the University of Utah, and Dr Nicolae-Alexandru Nicorovici, of the University of Technology, Sydney. They studied materials with bizarre optical properties first postulated in 1968 by Victor Veselago, a Russian physicist, to show that light could cancel itself out in some scenarios and make an object look invisible. This work remained a strange mathematical fantasy until six years ago with the creation of superlenses that can make objects, when placed near them, invisible. When an object is bathed in light of one colour, the light becomes trapped near the lens and "almost exactly cancels the light incident on each molecule in the object, so it has essentially no response to the incident light. Numerically we see that the molecule is effectively invisible."

This is a mathematical solution. The real test for any of these invisibility solutions will be when someone finally makes one and experiments with it. Until then, the best example of invisibility is that of Professor Susumu Tachi of Tokyo University, who made a suit with a video camera out the back, who's images were projected on the front of the suit, so it seems as though you were looking "through" the wearer. This didn’t quite work perfectly however, as you need to be looking from the right angle for it to be effective. So until our mathematical fantasies come true, we can only fantasise about a future where the Invisible Man is a possibility.

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What the Hack?

Computer hackers come in all shapes and sizes. Some are just curious to see what they can do and don’t cause any harm, others look for flaws in software design and work out ways to exploit them. Some seek power, others seek thrills, some steal money and others steal secrets. We see them in movies all the time. But the term hacker can mean many things, and they’re not all negative.

At their best, hackers may be people who know various programming languages and interfaces so well that they can write software expertly and quickly. These hackers can be brilliant at their tasks, writing detailed programs with little guidance in very quick time.

At their most interesting however, hackers can exploit computer security systems and gain unauthorized access through their own skills, tactics and knowledge. I’m sure that many listeners have been victims of this type of hacker, having perhaps had a Trojan horse, which is a program designed to look like legitimate software, but actually does something malicious, downloaded onto their computer.

A notorious, or famous depending on your point of view, computer hacker is Jonathon James, who obtained access to the source code on the International Space Station that controlled critical life sustaining functions such as oxygen filtering. He also intercepted communications between U.S. Department of Defense officials at the Defense Threat Reduction Agency who were discussing nuclear strategy, and obtained usernames and passwords of Defense Department officials. And he did this all at the age of 15!

Gary McKinnon is another infamous hacker, who is accused of the "biggest military computer hack of all time". The unemployed computer systems administrator is accused of hacking into 97 US government computers, including networks owned by NASA, the US Army, US Navy, Department of Defense, the US Air Force, and The Pentagon. The costs of tracking and correcting the problems he allegedly caused are estimated to be around $US 700 000.

Another, rather ingenious, hacker is Noah Burn of South Carolina in the US. Burn exploited a software flaw in the game EverQuest II so that his character within the game, a barbarian called Methical, could sell lots of desirable goods, and therefore make lots of virtual money. Now this might sound like it’s not worth the effort – after all, all this extra money is just virtual money, and you can’t spend it in the real world. However, with online gaming becoming more and more prevalent, a real life market has been set up on auction sites such as e-bay, whereby you can buy virtual goods for real life money – that is, you can buy the goods and have your character possess them, without having to earn them within the game. In this way, Burn made roughly $US 100 000 in the real world due to a minor glitch in his virtual world.

Indeed, this real life market for online commodities has taken off to such an extent that some players have been collecting real life money for destroying the property of other characters, or even the characters themselves. One such online character is Istvaan Shoaatsu, who is a mercenary destroying other characters for a profit within the game Eve Online. And whilst Shoaatsu may profit in the real world from these activities, those whom he destroys lose their own virtual money, which has taken time to earn and has a real life worth. Indeed, violence from the online world has spilled over into reality. Qui Chengwei from Shanghai, having loaned his valuable sword to a friend Zhu Caoyuan within the game Legends of Mir, actually murdered Zhu in real life when he discovered that Zhu had sold his sword on to another buyer.

This highlights an area where our laws are just not ready, as we have never had to develop laws for such situations. Another area where this is the case is in the situation of bio-hackers, who are similar to computer hackers, but instead of tinkering with computers and software, they experiment with DNA and other aspects of genetics. It is thought that in the future, computers themselves will contain biological devices. But until then, the risk of bioterrorism and biohackers with evil intent is high. Imagine if you could isolate the DNA of dangerous viruses and create even more deadly bugs? Tom Knight of the Massachusettes Institute of Technology thinks we have absolutely no choice but to try and do this better and faster than the bad guys, and work out ways of lessening the possible damage caused.

See Tim Guest’s book Second Lives, which will be published in 2007, for more information about online/offline adventures.

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Scientific Dating Tips

Some of us are pretty unlucky in love. The old tricks of buying flowers, buying dinner and whispering sweet nothings just isn’t working. Perhaps its time to turn to science to win us the heart of that special person. But can science successfully play Cupid? Here are some tips from society’s most lucky in love, the scientists.

Make your Body talk
Forget the pick up lines. Body language is more important than the smoothest of opening lines. When you meet someone for the first time, 55% of the initial impression is based on your body language, 38% is based on the tone, speed and style of your voice and only 7% on what you actually say! So what sort of body language should we employ? Mirroring the other person’s movements and posture is a good start. Most people do not realise they are being mirrored, but will view you favourably. Adopting particularly masculine or feminine postures can also help, like putting your hands in your pockets to puff out your chest.

When I look into your eyes...
It may seem like a pretty simple act, but looking into someone’s eyes can have a powerful impact. Gazing into someone’s eyes lights up parts of the brain associated with feeling good. Psychologist Arthur Arun performed an interesting study where he asked people, who had previously never met, to stare into each other’s eyes for four minutes. Their feelings of attraction rocketed compared to staring at other parts of the body. Indeed, one of these couples ended up getting married!

Our pupils dilate when we are interested in at what we are looking, and it has been shown that people are attracted to large pupils – in the way that people find big-eyed puppies cute! Indeed, in medieval Italy, ladies put bella donna in their eyes to make them look bigger. This is not particularly wide spread these days, as bella donna is a poison!

Be afraid, be very afraid
There is a strong connection between anxiety, arousal and attraction, and it has been found that couples who meet when physiologically aroused, or who experience fear together on a first date, have an increased chance of having romantic feelings for each other. No one is quite sure why this happens – it could be that the adrenaline rush from the danger is misinterpreted as attraction – but it suggests that a bungee jump first date could be a good idea. Or at least, choose the suspense or horror film over the chick flick.

Be Funny
Love and laughter go together. If you can make your partner laugh, you have a stronger chance of them falling for you. If you have ever noticed that couples in love tend to find each other funny whilst the rest of us think that their jokes are pretty bad, it is because a compatible sense of humour seems to be one of the keys to love.

Can there be more than one “one and only”?
Do we each only have one “soul mate”? Is there really such a thing as finding your one and only beloved in a world of over 6 billion people? Evolutionary psychologists at Indiana and New Mexico Universities used computer simulations to examine this question of how to best choose your partner from a set of prospective lovers. They set up their experiment such that the person making the choice of partner examined a bunch of potential partners to determine how attractive they were, and how high he should set his sights. Once this decision is made, based on those prospective partners he has seen, he goes for the next person who he comes across that fits his criteria.

The researchers found that one should only examine 9% of all the possible partners out there, before making your choice. For example, if you were at a party of 100 people looking for love, you should only scrutinize the first 9 possible mates you come across before focusing your attention on that special someone. Examining less than this number means that you do not collect enough information to make a good choice. On the other hand, examining more means that it is more likely that you wont choose your best possible choice as they are more likely to be amongst those you examined and then ignored before choosing. Whilst this model is far too simplistic to be an accurate representation of the search for love, it tells us that we should not search forever, as it is likely that we may let our true love pass us by.

So let us know how these tips work for you, as it would seem that love does not follow a rulebook.

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Sniffing out a partner

What makes you fancy someone? What is it that you look for in a partner? This week on Mr Science, we will continue our exploration of the science of love, and take a look at how your genes, your nose and even the Internet can all play a role in for whom you fall.

There are some facts that are unavoidable – some people are simply just beautiful. Perhaps they have symmetrical faces – it has been shown that men prefer women who are close to symmetrical. Perhaps their bodies contain the golden ratio, as discussed in previous weeks in the Mathematics of looking Beautiful. In women, men seem to look for full lips and soft facial features. In men, women seem to prefer broad shoulders and the appearance of sexual potency. The desire for these features seems to be conscious and universal.

However, not everyone can end up with the Brad Pitts and Natalie Portmans of this world. It would seem that people fall for those who have similar attractiveness, intelligence and "status" to themselves – that is, those within their league. If everyone fell in love with a movie star, only very few people would end up breeding, and this is obviously bad for evolution.

On the more subconscious level, a set of genes known as the Major Histocompatibility Complex (MHC), seems to play a role in to whom we are attracted. We actually look for people who have a different MHC to ourselves. The MHC helps us fight off pathogens, so the offspring of two people with different MHCs has a broader immune system than the offspring of parents with similar MHCs. And it would seem that our noses sniff out this difference. A 1995 study by Claus Wedekind of the University of Bern discovered that women prefer the smell of sweaty shirts from men who have a distinctly different MHC to themselves. This is similar to the situation with rats, who smell the pheromones in each other’s urine to determine their resistance to disease.

An interest exception to this rule is for women on the contraceptive pill. These women prefer men with a similar MHC to themselves. Women’s preferences also change throughout their menstrual cycle, as during periods of high fertility they prefer men with strong masculine characteristics, whilst at other times, prefer more stable caring men.

Another recent, rather Freudian, finding is that we seem to prefer a partner who reminds us of our parents. Men seem to prefer women who are like their mother, and women want the man of their dreams to remind them of their dad. David Perrett of the University of Scotland performed a computerised study where he morphed pictures of participants’ faces into the faces of others, and discovered that his participants preferred the faces that contained fractions of their own face – even though they could not consciously determine their own faces on the screen. He suggested that this was because these faces remind us of the faces we constantly see during our early childhood – the faces of our parents. It has even been suggested that we prefer someone to smell like our parents. It would seem that we are seeking our partner to possess an immune system which is a blend of the tried and true immune systems of a parents, and that of one that is completely different to our own, to make sure our offspring has a wide range of genes for immunity. We seem to desire a balance between inbreeding and outbreeding.

Not all relationships however are born out of compatible genes and smells. Many modern relationships start in that very modern of media, the Internet. There is growing evidence that the Internet can be more conducive to open relationships than first meeting in reality. This phenomenon has been called the “hyperpersonal” effect by Joe Walther of Cornell University, and refers to the fact that when communicating by typed messages, we have more time to construct our responses and are often more intimate and honest. By not having to look at, or hear the person to whom we are talking, we can focus solely on what we are saying and not the way we look or sound. This allows us to build positive impressions of each other without the visual clues that might have normally put us off. This means we get to know each other from the inside out. Walther also uncovered that, despite its ease, people are less likely to lie online, possibly because there are no uncomfortable consequences.

Another researcher, Katelyn McKenna of Ben Gurion University, thinks that in some cases, an attraction built on the Internet that may not have started in real life, may be strong enough when the couple do finally meet offline. Indeed, McKenna thinks that sometimes starting the relationship in the safe environment of the Internet, where people are more honest and open about themselves, may be preferable. The danger is that, because there is no physical contact, participants in online romance may fill the gaps with what they would like to believe about the other person, and not what is actually the truth.

The road to true love seems to be a mix of the conscious and the unconscious, and may take unexpected turns. Until next week, try and find yourself an object of affection, and next time on Mr Science, will we take a look at how you can best scientifically woo your love.

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Love is a many splendored thing

Love has inspired painters, songwriters and artists for centuries. Singers have cried that love will tear us apart and that love will lead us back together, that love can be tainted, and that the look of love is something to be desired. Some cultures have more than 10 words for love. But now scientists are starting to get interested in this fundamental human emotion, and this week on Mr Science, we will start a series of shows looking into this crazy little thing called Love.

The scientific understanding of love is still in its early stages, however when it comes to those warm tingly feelings inside us, it seems that our biochemistry is to blame. Right from the moment we are born, chemicals in our brain effect how much we bond with those around us. The love of a mother for a child is perhaps the most fundamental of loves, and scientists are now starting to understand that this love is cemented by a hormone called oxytocin. Late in pregnancy, the number of oxytocin receptors in the brain increases because of heightened levels of oestrogen. During childbirth, the hypothalamus gland releases high levels of oxytocin that then bonds to the many receptors, thus making the mother effectively “addicted” to her child. This makes evolutionary sense, as a strong bond between mother and child is essential for the child to survive.

Oxytocin is also thought to be associated with long lasting intimate relationships between adults. Oxytocin is released during intimate physical contact between partners, and boosts trust between partners whilst also helping people overcome “social fear” when getting to know each other. A study of “investors” and “trustees” at the University of Zurich suggested that with just a sniff of oxytocin, those playing the role of investors would hand over all their money to phoney anonymous trustees without any guarantee of its return. Those in love would recognise the thought that your partner can do no wrong.

But whilst oxytocin cements close relationships, other chemicals get us to that stage. Lust is driven by testosterone and oestrogen. These hormones encourage us to get out there and meet people, and cause the initial attractions. After lust comes attraction, and this is the stage that most people regard as being love-struck. You are unable to think about anything else and you spend hours daydreaming about that special person. Sometimes you don’t even need to eat or sleep. A group of neuro-transmitters called monoamines are to blame here. You are the victim of dopamine, which is also activated by smoking, adrenaline, which makes you sweat and your heart race, and serotonin, which has been shown to be associated with mental disorders. It would seem that you would have to be mad to be in love. Indeed, studies in Italy have shown that some people recently in love suffer some symptoms of Obsessive Compulsive Disorder. Some even suffered depression!

Another interesting chemical in the brain associated with long-term commitment is called vasopressin. The amount of vasopressin in the brain seems to determine whether or not a couple will remain monogamous. Monogamy, or having only one partner, is not as common among mammals as one may think. Although having monogamous parents could help in child raring, less than 5% of mammals have only one partner. Nature provides a good example of how vasopressin can determine monogamy. The Prairie vole bonds very closely to its mate, whilst its relative, the meadow vole, is promiscuous. It seems that the difference between these species is the amount of vasopressin receptors in the brain. In the prairie vole, when the hormone is released during physical intimacy, there are many receptors with which it can bond, and the deep monogamous relationship is cemented. In the meadow vole, there are very few receptors, and so the feelings of love are not generated and the meadow vole moves on to its next partner.

So it would seem that we are at the mercy of our biochemistry, and that love may indeed give us a mental disorder. In the next few weeks on Mr Science, we’ll have a closer look at what we look for in our perfect partners, and also how to best scientifically woo your lover. We’ll also take a look at internet dating.

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Venus - Hell's Kitchen

Imagine a planet that’s about the same size as Earth, made up of the same rocky material, with Earth-like features such as clouds and volcanoes, and just a little bit closer to the Sun.

But now imagine that this planet has a surface temperature hot enough to melt lead, an atmosphere that would crush you, and where it rained sulphuric acid everyday.

This place is Venus. Venus is named after the Roman goddess of love, but this week on Mr Science, we will discuss a planet that has nothing to do with love and is about as close to Hell as you can possibly get.

Back when the solar system was being formed, Earth and Venus looked quite similar – they were both rocky, inhospitable places with volcanic eruptions spewing carbon dioxide into the air. Both had water vapour in their atmospheres. On Earth, this water vapour turned into clouds and eventually the oceans. On Venus, which is 30 per cent closer to the Sun, it was slightly too hot for liquid water to form and eventually the sun's radiation broke apart the water molecules.

On Earth, the oceans dissolved much of the atmosphere’s carbon dioxide and helped create limestone and other minerals. On Venus, all this carbon dioxide, with no water to dissolve in, continued to accumulate in the atmosphere, until the pressure was 90 times that of Earth’s. This caused a runaway greenhouse effect. With radiation from the Sun not able to escape from this dense atmosphere, the temperature got hotter and hotter until the average temperature reached 450 degrees Celsius. It was liquid water, or the lack of it, that made all the difference.

So could we possibly ever go to this place? The first landing on Venus was in 1966 when a Soviet probe called Venera 3 crash-landed on the surface. In 1967, Venera 4 descended through the atmosphere sending back readings, but its batteries failed before it touched down. Venera 5 and 6 were crushed by intense atmospheric pressures. Finally, in 1975, a descent vehicle from Venera 9 made it to the ground. No human has ever been there.

On April 11 2006, the Venus Express, which is a European Space Agency mission, successfully assumed orbit around Venus, and it plans to map the Venusian surface for about two Venusian days. This may not sound like a long time, but this actual equates to about 500 Earth days. This means that Venus rotates very slowly. Another usual facet of Venus’s rotation is that rotates in the opposite direction to the other major planets – that is, the sun rises in the West and sets in the East. Scientists do not know why Venus rotates so slowly and in the opposite direction, but it is thought that is has something to do with solar heating of the thick atmosphere, friction and tidal forces.

So to survive on Venus’s surface, you would need to be able to withstand incredibly hot temperatures, intense atmospheric pressure and acid rain from the sulphuric acid clouds. It would seem therefore unlikely that life as we know it could live on Venus’s surface.
But some scientists, like NASA’s Geoffrey Landis, think that life may exist up above the clouds. At 50 km above the surface, the temperature range is between 0 and 50 degrees Celsius, the air pressure drops to 1 atmosphere and the gravity is 90 percent that of Earth’s – very pleasant conditions for life, or at least, microscopic life. Indeed, scientists have discovered that the chemical carbonyl sulphide is found in Venus’s atmosphere. This is a compound that is difficult to make using natural processes and is usually found as a bi-product of life.

But it would seem that Venus has nothing to with its namesake, the goddess of love. However, stay tuned for next week’s Mr Science, when we take a closer look at this topic of love, and see whether there is any science behind human attraction.

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A land of hobbits, giant rats and miniature elephants?

Ever wondered what it would be like to be stranded on a deserted island?

What if that island was a lost island of pony-sized elephants, gigantic lizards and even miniature humans? Sound far-fetched? Whilst the idea may be fanciful, scientists think they may have discovered such a place.

The island is called Flores, and is east of Java in Indonesia. A team of Australian and Indonesian paleoanthropologists and archaeologists were looking on Flores for evidence that the Homo sapiens species of humans – the species that we all are – migrated down through Asia and into Australia about 50 000 years ago.

What they found was truly astounding.

They found the remains of at least seven individuals of some type of human, but a type that looks nothing like us. These humans were only about one meter tall, weighed only 25 kg and had brains that were four times smaller than our own.

Scientists now call them Homo floresiensis, on account of where they were discovered, although they are more commonly, and perhaps cruelly, known as Hobbits, after the little human-like species from The Lord of the Rings.

What was even more surprising was that their remains suggested that they may have survived as recently as 12 000 years ago – which means that some of the stories passed down by the local people in the area about seeing little people could possibly be true! Even an editor of the reputable science magazine Nature has suggested that it is not beyond the realms of possibility that one day we may find a human-like species like this still alive and well somewhere in an uncharted part of the world. It is even more likely that, as Homo sapiens and the hobbits were living in the same part of the world at the same time back then, they probably came face to face.
There is currently debate about how to classify these hobbits. It is not sure yet whether they descended from Homo erectus – the same species from which we Homo sapiens descended – or whether they could even be an off-shoot of modern humans – they did have quite sophisticated tools, and although their brains are small, they are big for their size.

It is thought that Homo erectus, a tall not-quite ape, not quite homo-sapiens creature, travelled out of Africa, colonised Asia and then stopped. There’s never been evidence that they travelled over water – simply because they weren’t smart enough. Is this evidence that they did? Or is this evidence that these hobbits are more like us than we think?

What seems clear though is that the reason this species is so small is because of the conditions in which it lived on the island. When they came to the island, and its unsure how that happened at the moment, they would have found a small island with limited resources. As generations passed, they evolved to get smaller and smaller, as in this way they would require less food to survive. Also, having a smaller body in the hot and humid conditions meant that was easier to cool down and less heat was made within the body when they moved around.

Some scientists think that this is an example of island dwarfing, which is a biological phenomenon by which the size of an animal isolated on an island shrinks dramatically over generations. It is a form of natural selection in which a smaller size provides a survival advantage.

But these hobbits were not the only species on the island that were a little strangely shaped. Dwarf elephants were also found on the island and were probably hunted by groups of their hominid counterparts. These animals, called Stegodons, were smaller than modern water buffaloes and also suffered island dwarfing.

Not every species on Flores is small though. In contrast, Flores is still home to a giant rat, which has a head and body size of about 45 cm, and a tail length of up to 70 cm, which means that they can stretch over 1 m! The island is also home to the Komodo dragon, a giant carnivorous lizard that can be as long as 3 m and weigh around 70 kg. If its initial bite doesn’t kill its prey, the over 50 different strains of bacteria in its teeth will. This prey includes pigs and even water buffalo. It might have been able to stay huge on the island, unlike the elephants, because these elephants, and perhaps even our hobbit friends, were the perfect meal size for them.

But whilst the giant rats and dragons survive to this day, the mini humans and elephants do not. Scientists think that they fell victim to a volcano eruption about 12 000 years ago. But could these strange and wonderful species exist somewhere else in the world? Be careful next time you’re shipwrecked and wash up ashore on a deserted island. A race of three-foot high humans who hunt elephants that only come up to your waist, and eat rats as big as dogs may await you. And be careful of the dragons with deadly bacteria-laced saliva. Who ever said science was dull?!

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Want to travel through time, or to the edge of the universe?

Imagine seeing the great wall being built, visiting your great, great, great grandchildren in the 23rd century, or instantly travelling to the other side of the universe.

Time travel and wormholes used to belong to the minds of science fiction writers. But, with a little inspiration, scientists have begun to show us that science fact can be just as strange as science fiction.

Einstein's special theory of relativity shows that time travel into the future is actually possible – there is no reason why we can’t do it. We just don’t know how to yet. Einstein’s theory suggests that the way we feel time going by is related to how fast we are moving. Objects travelling at speeds close to the speed of light (about 300 000 kilometres per second) age slower than objects which are not moving.

In 1975, Professor Carrol Alley tested Einstein's theory using two synchronised atomic clocks. Carrol loaded one clock onto a plane, which was flown for several hours, while the other clock remained on the ground. At the end of its flight, the clock on the plane was slightly behind the one that was left on the ground – that is, time had actually passed more slowly for the clock on the plane than the one on the ground. It had travelled every so slightly forward in time. So to travel into the distant future, somehow scientists need to come up with technology than can allow us to travel somewhere near the speed of light.

But what about time travel into the past? In theory, nothing in the laws of physics is stopping us from doing it, however, no one quite knows how to do it.

According to Einstein's theories, any object with mass will cause a warp in space-time, similar to a bowling ball sitting on a mattress. Because space and time has been stretched, clocks operate slower close to Earth than in the vast areas of space. Previous theoretical designs of time machines have used this concept of mass distorting space-time, however these theoretical machines require a tremendous amount of energy to work.

A professor of theoretical physics named Ronald Mallett came up with another idea. He believes that anything containing energy could warp space-time, and as a result, he has designed a time machine that uses light, rather than mass. His theoretical time machine consists of a ring of two intense beams of light, circling in opposite directions. By slowing the light down in an ultra-cold bath of atoms and increasing the intensity of the beams, he thinks space-time inside the ring would become warped. Eventually, space and time would become so distorted by the circling light that time would become a dimension similar to space - a dimension that you could move along! If you entered the ring and walked in the correct direction, you could walk backwards through time - maybe even passing yourself as you entered the ring!

However, there are lots of problems putting Ronald's theory into practice. The temperature of the ring would have to be close to absolute zero (-273°C), so humans would find it difficult to use. And it would also be impossible to travel back to a time before the machine was switched on. Perhaps this is why we’ve never met anyone from the future!

So, what about these wormholes? Can we travel across the universe instantly using one?

The universe appears as three dimensions in space (up-down, left-right, and forward-backward) and a fourth dimension known as time. Wormholes are connections between two different places in space and time. This is difficult to visualise in four dimensions, but it is easy to see in two. Imagine two points on an sheet of paper. You could travel between the points by following a line on the piece of paper, or you could fold the paper over so that the two points touch. By folding the paper, you are making a 'wormhole' in the two-dimensional paper world.

Although there is no experimental evidence for the existence of wormholes, theorists believe that they may exist. Wormholes first appeared possible in Einstein's theory of gravity, in 1913. However, physicists had almost forgotten about them until the eighties, when Carl Sagan included them in his novel Contact, in which the main character travels to another part of the universe to visit another civilisation.

To be stable, wormholes need lots of what’s called negative energy. Quantum mechanics suggests that it exists, but we haven’t found it yet, and we don't know whether the laws of quantum mechanics allow enough negative energy to be concentrated in such a way as to allow wormholes to exist.

One possible location for wormholes is at the centre of black holes. Travelling through one of these might prove extremely difficult however, since the wormhole would be so unstable that it would collapse as soon as a spaceship (or even a ray of light) entered it. This is because there would not be enough negative energy to hold it open.

So don't pack your bags for a trip to the other side of the galaxy just yet, or for a trip back in time. Scientists haven’t found any wormholes yet, or made a time machine. So we do know that a wormhole is not going to get you across Beijing in time for work after you’ve slept in.

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Black Holes

What are black holes? Can we use them to travel through time? Where are they and what creates them?

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What is DNA?

What is DNA? What does it stand for and what does it do? Can we change it and change ourselves?

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What are Dreams?

Why do we dream? Do they mean anything? Can we control them?

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What do ears do?

What do ears do? Do we really need them? How do they work, and what else do they do but help us hear?

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Global Warming

What is Global Warming? Are humans creating it and is there anything we can do about it?

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Can we live forever?

Can we live forever? What is stopping us from becoming immortal? Are we the first generation to live to 150?

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Can Scientists Predict your Music Taste?

Has it come to this? Can science now predict something as personal as the types of music that someone likes? This week we take a look at some of the advances being made into helping us broaden our music appreciation, and predict the unpredictable.

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The Planet Pluto

Where is Pluto? Is there life there? Is it even a planet? This week on Mr Science, we are going further out into the solar system than ever before.

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Editor: Note that Pluto was demoted from its planet status in 2006 after this show

Volcanoes

What are volcanoes? What causes them, and where can we find them? Some of the biggest volcanoes on Earth are under the ocean. Are the connected to Earth quakes and tectonic plates?

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The mathematics of looking beautiful

Looking good is important to a lot of people. Gyms, cosmetic companies, clothes stores and fashion magazines all exist because of our preoccupation with looking good. So what makes someone attractive?

Greek philosopher Plato believed he found the answer in the fourth century BC, and discovered it candidate in the most unlikely place of all: mathematics.

Plato was interested in designing beautiful shapes. As strange a hobby as this may seem, his results were even stranger. When measuring the dimensions of rectangles that he considered beautiful, he found their ratio was always the same ‑ 1.618.

Although this number is nothing special to look at, it has intrigued Plato and generations of mathematicians for centuries. The ratio 1.618 can be found in many examples of objects that we consider to be beautiful ‑ from the human body to music, architecture, nature and art. This number is so special that it has been called ‘the golden ratio’.

What exactly is the golden ratio?
The golden ratio can’t be written exactly as a decimal number, because it is irrational. It is a decimal that continues on and on, without any apparent repetition.

The best definition of the golden ratio is it is the only number that when squared is equal to the sum of itself and one. In 1996, a mathematician called Greg Fee programmed his computer to compute the golden ratio to ten million places. It took Greg’s computer approximately 30 minutes to complete.

There is an easier way to estimate the golden ratio using the Fibonacci sequence. This is a sequence of numbers where the next term is the sum of the two previous:

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 … and so on.

If you divide each number in the sequence by the one before, you may notice that the quotient approaches the golden ratio:

1/1 = 1, 2/1 = 2, 3/2 = 1.5, 5/3 = 1.666…, 8/5 = 1.6, 13/8 = 1.625, 21/13 = 1.615…

Fibonacci in nature
The Fibonacci sequence is often found in nature. The number of petals on a flower is often a Fibonacci number. Buttercups have five petals, lilies and irises have three petals and daisies often have 34, 55 or 89 petals. You might find some Fibonacci numbers in other places in your garden as well. Seeds on flower heads, such as on sunflowers, are often Fibonacci numbers. Patterns on pinecones are also based on Fibonacci numbers.

Sometimes these numbers are not exactly Fibonacci. In the case of pinecones, this can be due to deformities produced by disease or pests. In this case, the absence of the Fibonacci sequence indicates that the pine tree is not well.

Animals also display the Fibonacci sequence. The most spectacular of these are seashells. You can recreate a spiral sea shell pattern using a compass and a ruler.

Start by drawing two unit squares side by side. Together these squares form a rectangle. On the bottom of this rectangle, add a 2x2 square to make a new bigger rectangle. Beneath this new rectangle draw a 3x3 square. This creates a larger rectangle. Each rectangle is known as a Fibonacci rectangle, because the dimensions of each new square follow the Fibonacci sequence.

To complete the spiral, use the compass and to draw a quarter circle in each square to form a spiral. This shape is called a Fibonacci spiral. Similar spirals are found on snail shells and seashells.

The golden ratio in the human body
It may be surprising to know that the golden ratio can be found in the human body. Your hands contain three bones in each finger (you may notice this more by bending them). The ratio of the longest bone compared to the middle bone and the ratio of the middle bone compared to the smaller bone are both close to 1.618.

Another place you will find the golden ratio is your height. Measure how tall you are and compare this to the distance between your feet and navel. Their ratio is close to 1.618. Your face may also contain the golden ratio. What is the ratio of the width of your mouth compared to the width of the bottom of your nose?

Some people think that the closer certain ratios in your body are to the golden ratio, the more attractive you appear.

Can you find the golden ratio anywhere else in your body?

Art imitates life
The golden ratio can be found in art, architecture and music. The famous Greek sculptor, Phidias, was known to use the golden ratio in his sculptures of the human body. The most famous Greek building, the Parthenon, is 1.6 times as wide as it is tall. Leonardo da Vinci also used the golden ratio. He would frequently divide his canvas in this proportion.

The golden ratio has also been used by musicians. Mike Kay, an American mathematician, has examined Mozart’s sonatas and found that most of them divide into two parts exactly in the ratio of 1.618:1. Whether this was intentional or intuitive is not known.

Another researcher, Derek Haylock, found that the famous opening motto in Beethoven’s fifth symphony is repeated at the golden ratio point from the beginning of the song (32 percent of the way). Intriguingly, it is also heard at the golden ratio point from the end of the song (68 percent of the way). Other composers that appear to have used the golden ratio in their music were Bartok, Debussy, Schubert, Bach and Satie.

Is the golden ratio the key to looking good?
No. Everybody has his or her own opinion as to what is good looking. However, the golden ratio has been used in the design of various works of art and architecture to increase their appeal.

In living organisms, it seems the presence of special numbers and proportions has provided some sort of evolutionary advantage. In nature, plants with Fibonacci numbers may be healthier and pest-free. Animals with these ratios may also appear healthier and more desirable to mates. However, the golden ratio is not the whole story. Beauty still escapes a complete explanation.

The mp3 for this show can be found here