Posts by: João Medeiros

The way we move and mobile phone viruses

By João Medeiros

One of the highlights of the “Science Beyond Fiction” conference in Prague was Lazlo Barabasi’s talk – “From Human Travel Patterns to Mobile Viruses”

Barabasi, author of the excellent book “Linked” , is one of the world experts on the topic of social networks.

In his talk, Barabasi presented novel insights about the science of human mobility patterns. The applications of such a study are incredibly wide-ranging, from understanding of how ideas and diseases spread, to the planning of traffic and urban spaces.

As one might guess, there is a huge element of randomness in the way we move.
Einstein, of course, was the first to theorize about random walk theory in the context of Brownian motion – the drunkard sailor paradigm (which constituted the first evidence for atoms).

The paradigm for how people move was first established by a series of studies by G.M.Vishwanathan on the mobility patterns of tagged birds and monkeys. What Vishwanathan found out was that animals do not follow the drunkard sailor pattern (ie, a Gaussian pattern) but instead follow a pattern compounded of lots of small steps with some big jumps, the so called Levy flight pattern, which is described as a power law distribution.

The first challenge in studying human mobility is how to get the data. Equipping millions of people with GPS track systems is prohibitively expensive (and probably ethically wrong).

But mobility data can be extracted from a variety of datasets which indirectly inform us of how we move.

For humans, this was first studied by Brockmann, who studied the motion of dollar bills (an explanation of their method can be found in their website What Brockmann found was that humans also obey the Levy flight pattern.
Barabasi also studied the mobility problem, using a mobile phone database composed of 7 million users, tracked between 2004 and 2009. His findings support the dollar bill findings.

Barabasi and collaborators (among whom is Cesar Hidalgo, who wrote a feature for PW last December) further discovered that the shape of human trajectories can be grouped into distinct categories according to typical ranges of motion, say one group for people who tend to move within a radius of 3 km, other for people who have radius of motion in the order of 100 km, etc.

What he found, was that within each category, the scaled patterns of motion are indistinguishable. This property – universality – means that all categories of human travelers can be described by one unified model.

This is important to understand many phenomena that derive from human mobility patterns. One such application is the understanding of mobile phone viruses.
Paradoxically, the first insight into the study of mobile phone viruses is to understand why mobile phone viruses are really not that relevant at the moment.

Experts estimate that there are approximately 600 varieties of mobile phone viruses. However, they exist only in smartphones, which, at the moment only detain 5% of the mobile phone marketshare.

These viruses spread in two ways. One, via Bluetooth, spreads in a manner similar to influenza, ie, related to physical proximity. The second mode of transmission is via MMS. These viruses spread in a manner akin to computer viruses and therefore have a capacity to spread non-locally.

In other words, the spread of Bluetooth virus depends on human mobility patterns, whilst MMS viruses depend on individual social networks. Understanding their modes of propagation leads us to understand their patterns of spreading. Simulations show that Bluetooth viruses may take days to reach everyone within a given region. MMS viruses, on the other hand, take only a matter of hours before reaching a maximum level of contagion. This saturation point is highly dependent on the level of market share of the smartphones.

MMS viruses are not dangerous below the level of 10% marketshare. Above that, however, we get a phase transition point and the virus can spread quickly everywhere within a matter of hours.

At the moment we are under that threshold, but when we reach that critical point, mobile phone viruses will become a serious threat to communications, especially since standard counter measures, such as anti-virus, are very difficult to install in smartphones due to the inherent memory capacity limitations on those phones.

Beyond the specific topic of mobile phone viruses, the work of Barabasi shows how mobile phones are quickly becoming a social experiment on itself, a gold mine of data in the study of social networks and human mobility patterns.

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Quo Vadis Quantum Information Science?

By João Medeiros

Just attended one of the best talks so far, here at the “Science beyond Fiction” conference in Prague — a really exciting, wacky and speculative talk by Artur Ekert, on quantum information science.

To Ekert, the questions that are used to “sell” quantum information science to “deciders” and funding bodies are usually of two kinds. A first argument, more scientifically motivated, sells the point that the true power of quantum computation is yet to be achieved, a computational capacity that will likely teach us much more about the fundamentals of nature. The second, more pragmatic approach, appeals to the exploration of the true fundamental limits in exploring quantum systems and what constraints they put on technology.

On the issue of framing the subject of quantum computation, Ekert says that it is really interesting how people from different cultural backgrounds react to the topic.

For instance when discussing the matter with computer scientists, Ekert uses a more philosophically inclined, logic based approach. According to him, computer scientists are naturally not really fond of atoms and messy quantum systems.

The question he asks his computer scientist collaborators is whether it is possible to construct a logic gate operating on a single bit, such that the same two consecutive operations produce a flip of the bit. Classically, of course, you cannot. But this is a possibility when using quantum systems.

Indeed, one of the fundamental differences between quantum and classical computational systems exists in the respective nature of the logical operations allowed by each system.

The bottomline realization is that information and computation are intimately linked to physics. Information is physical. This conclusion was to many computer scientists a shock and it marked the intellectual revolution that kickstarted quantum information science.

Physicists now realize that if you change the physics you change the nature of information. This has been a surprising revelation to many computer scientists, who since the work of Alan Turing have been playing with classical computer logic without a physical foundation, a logical framework which somehow worked.


Ekert also pointed out that quantum computation is one of the truly interdisciplinarity subjects.

Not only it has brought together mathematicians, computer scientists and physicists, but it has also brought people together within physics, scientists that beforehand would not talk to each other simply because they were using completely different jargon and codes. A common denominator was found in the language of quantum logic gates.

Ekert, who is based in Singapore, compared this situation with the way that sometimes Koreans and Chinese use to communicate: not by speaking, but via written characters.


Ekert also mentioned that recent advances in the study of the quantum aspects of life, such as the study of the role of quantum coherence in photosynthesis, opens the door to discover quantum computation already happening in natural systems. This is a most fascinating topic that will be featured in an upcoming feature by Paul Davies for PW.


The final aspect discussed by Ekert was the philosophical aspect of quantum computation, an side of science which has not been avoided by physicists. According to Ekert, quantum Information has elevated the questions about the nature of reality, randomness, complexity to the level of bona-fide scientific conundrums that should be addressed, rather than ignored.

Ekert himself is partial to question about the nature of randomness, the question of whether it is really possible to have events that have no underlying cause? What is so interesting about this question is that it essential goes against one’s understanding of science, which is intrinsically motivated by the notion of causality of phenomena in nature.


In the next issue of PW, Ekert authors a feature about Girolamo Cardano, the “gambling scholar”. Cardano was a Renaissance mathematician which by himself discovered the basic notions of probability and complex numbers, two of the fundamental pillars of quantum theory.

In the future, Ekert will write again for PW about quantum information science.

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The future of science

By João Medeiros

I’m in Prague attending the European Future Technologies Conference — “Science Beyond Fiction”. It has so far been prolific in ideas and science-fictionish future promises, despite a bumpy start.

Viviane Reding, the European Commissioner for Information Society and Media, and Mirek Topolanek, the Czech PM, were the high profile names planned to open the proceedings. They were, however, conspicuous by their absence.

Topolanek, understandably, is perhaps more concerned with his political future than with the future of science right now, after losing a no-confidence motion in Parliament last month. The Czechs also presently hold the EU presidency, so the overbooking of Topolanek’s diary is understandable. One can only hope that he can multitask.

Reding, on the other hand, used cutting-edge European technology to address the delegates via a prosaic video-stream. Given that she is the Commissioner for Information Society and Media, the symbolism is laudable.

Speaking on a blue background of distorted stars and clouds dangerously resembling a psychedelic motif, Reding proposed to boost Europe´s high-risk research into future technologies by doubling the current level of funding by 2015.

“Europe must be inventive and bold – especially in times of crisis. Research seeds innovation which is key for Europe’s long-term global competitiveness. Scientific and revolutionary breakthroughs constitute enormous opportunities and we must bring the best brains together to make the most of them,” said Reding. “Combining efforts of the 27 EU countries and stepping up cooperation with global partners is essential for Europe to take the lead in future information technologies that can yield radically new solutions for European citizens in domains such as health, climate change, the ageing population, sustainable development or security.”

In other words, Europe needs catch up with the US, China and Japan.

Unlimited computing power, computers mimicking the brain, mind controlled wheelchairs and friendly robotic companions are all part of this European sized mega super project. This initiative comes in the context of the Future and Emerging Technologies (FET) programme to promote long-term and high risk research in quantum computing and communications, nanoelectronics, neuro- and bio- information science, advanced robotics and complex systems.

Some of the research that resulted from FET sponsorship is in show here at an Exhibition.

On the “friendly robotic companions” category, I saw NAO, an extremely self-conscious robot that talked non-stop whilst pushing boxes around (or in the words of the researchers involved, “learning physics”). It did not really convince me, but kudos for looking so helpless and cute.

I was also the only volunteer to test drive a simulator type head-set – immersive journalism at its best — and had to control a joystick to run over black squares on a virtual road. I’m still trying to figure out why.

The issues of high-risk research and funding of basic science, of course, were already timely featured in PW’s May issue, on the excellent article by Mark Buchanan, “In search of black swans”
Glad to see that PW is driving the European science agenda.

Highlight of the day: Anton Zeilinger’s talk on Quantum Information (more on that later)

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The Renaissance of Astronomy

Herschel space telescope (Courtesy: ESA)

By João Medeiros

According to Jonathan Gardner, from NASA, we are going through an unparalleled renaissance of astronomy, maybe only comparable with Galileo´s pioneering efforts. In fact, most astronomy talks today seem to start with the words “We now know…”

Speaking at the IYA opening in Paris he noted that over the past decades, we’ve discovered inflation, the universe´s flat geometry and that 95% of the mass of the universe is actually not on the periodic table.

Part of the reason for this renaissance has been the dream team of space telescopes, Hubble, Chandra and Spitzer. As this generation of the telescopes is reaching the end of its days, a new one is getting ready to launch. The space telescope Herschel will be launched in April, Hubble telescope is going to be granted a new lease of life with another serving mission May this year, and 2013 will see the launch of the James Webb telescope.

There´s also Planck, Herschel´s sister mission (like the fact that it´s a she, to balance that aforementioned gender inequality in science), planned to launch this year.
Hubble´s revamping is going to be take place in May. They are going to replace Hubble´s batteries, implant new gyroscopes, repair some of the instruments and put two new pieces of tech on the satellite: the cosmic origins spectrograph (which is going to measure the cosmic web of gas between the galaxies) and the WFC3 (wide field camera, that will look for high redshift supernovae).

The new generation of space telescopes is going to prioritize the study of star formation, exoplanets (undoubtedly THE topic of astro at the moment) and the end of the dark ages, when the first galaxies formed and ionized the interstellar medium. All in the spirit of Carl Sagan´s philosophy “Somewhere, something incredible is waiting to be known.”

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Chasing Robert Wilson

By João Medeiros

Bob Wilson, discoverer of the cosmic microwave background (with Arnos Penzias), Nobel laureate, is one of the big celebs here at the IYA opening. Students chase him like paparazzi. Good to know there is such a thing as science fanclubs.

I managed to scare away the students and get ten minutes with Wilson. I had to thank him for having given me a PhD topic, after all. We spoke about scientific method and the importance of science journalism.

A curious thing about the discovery of the CMB is that Wilson only truly realized the importance of his discovery when he read about it on the NY times. Being a typical postgraduate at the time (he was 29), back in 1965, he woke up at lunchtime the day after his discovery was published, and it was his father, visiting from Texas, that brought the newspaper with the news. “I didn´t really have a clue of the importance of what we had done until then, thanks to that journalist,” he said.

Wilson didn´t actually take cosmology seriously, given all the speculation back then (nothing much changed then). In fact, he was actually more philosophically inclined to believe in the steady state theory rather than a dynamic universe, partly because Hoyle had been his cosmology lecturer.

According to Wilson, his discovery made cosmology the big industry that it is today, something that we would never had imagined would happen in the slightest.

Given the serendipity of Wilson´s discovery, he says that it hadn´t been for him and Penzias, then certainly someone else would have discovered the CMB sooner or later (in fact, at the time of Wilson and Penzia´s discovery, David Wilkinson was building an antenna to specifically detect the cosmic radiation). Wilson believes in Robert Merton´s theory of multiples, that discoveries are the product of individuals, but of the times.

The NY Times episode shows that Wilson thinks science journalism plays a fundamental role to science. He still reads the New York Times and various science magazines, to keep up to date on what is going on in science. He says he much prefers it to scientific papers, which take a lot a time and effort.

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Astronomy comes to Paris

Catherine Cesarsky (Courtesy: ESO)

By João Medeiros

It´s the year of deflation, the year of Obama, and the International Year of Astronomy. It started here in Paris, the City of Lights, by the Eiffel Tower, at the UNESCO HQ. The Opening Ceremony attracted more than 100 countries represented by astronomers, industrialists, diplomats, artists, a Kepler impersonator and the odd journo. We are celebrating 400 years since Galileo, the father of modern science, turned the telescope up and saw something amazing.

Catherine Cesarsky, president of the International Astronomical Union, said the vision for the International Year of Astronomy is going to be geared outwards, towards the public.
“After years of preparation, the time has come to launch this year, during which the citizens of the world will rediscover their place in the Universe, and hear of the wondrous discoveries in the making. “

Indeed, the lofty goal of the IYA 2009 is not to launch a super science program but to return astronomy to the public through a series of initiatives that will include the Dark Skies Awareness a reclassification of archaeoastronomy sites as UNESCO´s world heritage sites.

Speaking to Physics World, Catherine Cesarsky, expressed how much she wishes that astronomy reaches the public again, as an entry point to science and to a scientific world view, so necessary today. She said that, from her own experience, the younger generations, 10 to 14 years olds, are usually enthralled by astronomy popular lectures. However, from then on, adolescence kicks in and it becomes harder to excite the audiences — it´s difficult for a teenager to appreciate the mysteries of the universe when its hormones are playing no rules football. But it doesn´t matter much, Cesarsky believes, since the most important part of science communication is to plant the seed for the excitement for the wonders of science when they are really young.

Cesarsky also worries about the gender asymmetry in the physical sciences and about the “leaky pipeline effect”: you get a fair proportion of women at undergraduate level that somehow are all but gone in academia. The discrimination, fortunately, is not as palpable as it was back in the days when Cesarsky did her studies in Buenos Aires. Obviously a bright student, she was once complimented by her head of department in the following nuanced manner “It´s funny, I always thought physics wasn´t for women”.

The conference opened with a series of talks on Mayan and Islamic astronomy. I´ve always been fascinated by the role played by ancient astronomy in society, bridging primordial religious experience to a fundamental relevance to agriculture and economy. According to Martin Rees, also present in the ceremony, “astronomy is, if not the first, the second oldest science, after medicine”.

Throughout history, astronomy inexorably lost relevance to society. However, it still relates with the big and the meta-questions. To Cesarsky, that´s where the relevance of astronomy lies. “We have one sky, and that´s what should truly unite people. Astronomy, like other sciences, but astronomy in particular, is a peaceful, soul-searching activity that encourages a truly global culture”.

Of course, 2009, is also the year of Darwin. In the words of Martin Rees, “Both astronomy and Darwinism provide a beautiful narrative for humanity, that starts right from the beginning until the intelligent species that we are today”

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A one-way street called ‘Physics+Biology’

Physics of Medicine Institute in Cambridge

By Joao Medeiros

I’ve just spent the last couple of days in Cambridge for the opening of the new Physics of Medicine Institute (pictured right) at the Cavendish Laboratory. The new institute will serve as home for scientists who are essentially bilingual in biology and physics. The Grand Opening was part of the Physics of Living Matter conference, which displayed the rich variety of problems that biophysicists are trying to tackle: medical imaging, new materials for medical purposes, systems biology, the role of mechanical processes at the cellular level. This is stuff that could bring biology to the next level.

It’s interesting to notice that this Physics+Biology is only a one-way street. The physicists are bringing their quantitative tools to biology, not the other way around. Biologists are not quantitative scientists, and this, in the long run, is a recurrent problem in the field. Descriptive tools can only take you so far, and applied mathematics are fundamental to bring out the big picture on fundamental scientific questions. A biologist at the conference confessed to me that physicists are always needed when there is the impending need to renew the paradigm in biology.


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An ethnic theory for plane crashes

By Joao Medeiros

Malcolm Gladwell
Malcolm Gladwell (Courtesy; Brooke Williams)

Malcolm Gladwell, the virtuoso author of Tipping Point (which covered the work of physicists like Duncan Watts and Albert-Laszlo Barabasi and Blink, came to London for one day to present his new book, Outliers, to a packed audience at the Lyceum Theatre.

Gladwell is a maverick science journalist (or what “maverick” used to mean pre-Sarah Palin). He invented “pop economics” with his writing, spawning a whole new class of books like Freakonomics, The Long Tail, Here Comes Everybody, …. He works for the New Yorker, where he regularly writes about his niche subject: everything.

Gladwell is not a typical science journalist. He’s an original observer (not necessarily an original thinker — he defines himself as a communicator of science) that is driven by his own curiosity rather than following the agenda of scientists. Whereas most science journalists browse the scientific literature in search for the “what’s hot in science”, Gladwell follows his own instinct and curiosity. He starts his stories by asking by asking very simple questions about pretty much anything that crosses his way: “What is Cesar Milan ( from the TV show “The dog whisperer”) secret?”, “Why is there only one variety of Ketchup?”, “Why do we usually relate genius to precocity?”, etc etc These are questions that most people probably dismiss as random daydreaming divagations.


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On a lake in southern Germany

(Photograph courtesy of Edda Praefcke)

By João Medeiros

Part of my job as Features Editor on Physics World is to dig up great ideas for possible feature articles. That’s one reason why I am spending this week on an island in Lake Constance in southern Germany at the 58th meeting of Nobel Laureates at Lindau.

The meeting, which is held every year, gives top young students the chance to hear, talk to and debate with leading researchers from a particular field of endeavour. This year’s meeting is dedicated to physics and there are some 25 Nobel-prize-winning physicists here as well as over 550 students.

Yesterday we were treated to a fascinating debate about the Large Hadron Collider (LHC) at CERN, featuring Nobel laureates David Gross, Martinus Veltman, George Smoot, Gerhard ‘t Hooft and Carlo Rubbia, along with LHC accelerator supremo Lyn Evans and CERN chief scientific officer Jos Engelen.

Chairing the session was my predecessor in the Physics World features hot-seat Matthew Chalmers, who is now forging a career as a freelance science journalist.

Some speakers, like Smoot and Gross, preferred to talk about the hope that the LHC will yield a cornucopia of new physics , prominently of Higgs bosons and supersymmetric particles. Others, like Veltman and Rubbia, took a more cautious stance as to what might be discovered.

The experiment itself is a complex beast and will take years before the experimentalists understand it completely. The computing challenge is also gargantuan: the proton-proton collisions will yield some 109 events per second, of which only 200 can be saved into a disk.

This means there is a huge responsibility on the shoulders of the thousands of young researchers working in the bowels of the LHC to make sure that the interesting events are the ones that get saved into the computing grid.

As Rubbia told the meeting: “The discussion about the Higgs is not the right discussion at the moment. This is a very complex machine, and presumably, it will take years before we understand it properly. One should let the physicists do their work instead of pressuring the scientists for results.”

I hope to tell you more about what’s been happening here on Lake Constance later this week. Meanwhile, back to those Nobel laureates…

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