Causality works bottom-up and top-down at once (Image: David Maitland/Millennium Images)

Fritjof Capra goes beyond The Tao of Physics with The Systems View of Life, a much-needed vision of biology with a dash of Eastern mysticism

WHEN I was about 17, I was briefly transfixed by the teachings of Eastern mysticism. I read everything I could about Zen Buddhism and Taoism, and pored over books by spiritual figures who claimed that ordinary consciousness could be transcended through discipline and meditation. I had tantalising visions of suddenly achieving “enlightenment” or “oneness” with the Godhead (although I had no idea what that was). To me, it all sounded impossibly cool.

As I also loved mathematics and physics, I picked up the bestselling bookThe Tao of Physics by physicist Fritjof Capra. It introduced me to weird concepts from quantum theory: things like entanglement and non-locality, which Einstein famously called “spooky action at a distance”.

Capra convinced me there were surprising parallels between these aspects of modern physics and Eastern mysticism, that what Buddhists had been saying for centuries about the interconnectedness of everything in the universe sat quite well with today’s physics. His wonderful book kindled a fascination with quantum theory which I have never lost (although I gave up on mystic enlightenment long ago).

I think Capra is now ready to inspire a new generation of young readers in much the same way, only with a focus on systems biology rather than quantum physics.

In The Systems View of Life, Capra and biochemist Pier Luigi Luisi explore how modern biology, in trying to understand the self-organising, adaptive and creative aspects of life in all its forms, has by necessity turned to a holistic, systems view emphasising pattern and organisation.

But the main point of the book isn’t merely that systems biology is fascinating. More importantly, Capra and Luisi argue that many of the most important problems we face today – from financial instability to climate change and ecological degradation – reflect our collective inability to appreciate just how the world operates as a holistic, networked system in which every part depends on every other.

There may be solutions – even simple ones, they suggest – if we could manage to start thinking in this way, and the book is their effort to help this along. It’s partly an enjoyable survey of exciting new developments in systems biology, valuable to any student of biology or science, and partly a bold blueprint for how we might preserve our future on Earth using the systems perspective on life and what sustains it.

You won’t find much by way of dramatic narrative about scientists making discoveries. Rather, this is a book of ideas and argument. Some of the scientific history is quite familiar, and many readers will be able to skim earlier sections on the rise of classical physics, or revolutions of Darwinian evolution, relativity and quantum theory. That said, Capra and Luisi use this history as a useful lens to examine how human thought has had an on-again, off-again relationship with systems thinking for centuries.

They also bring back to life some of the foundational figures in systems science, now mostly forgotten. For example, I had heard of the Austrian biologist Ludwig von Bertalanffy, who in the 1930s developed general ideas about the organising principles of living systems. What I didn’t know is that he also introduced the important notions of open and closed systems. An open system is “open” to an outside world, as our planetary biosphere is to the flow of the sun’s energy. Such systems naturally develop complex, dynamic structures reminiscent of life, things absent in closed or isolated systems.

I had also heard the name Bogdanov, but had no idea that Alexander Bogdanov was a Russian polymath who developed similar ideas around the turn of the 20th century; his work is still largely unknown in the West.

It isn’t until chapter 7 that the book really takes off, moving with full force into the more recent systems revolution in biology. Capra and Luisi take an adventurous expedition through topics from genetic regulation to ecology, and from climate science to the origins of life, in every case emphasising the necessity of taking a holistic perspective if we are to make progress.

They ask: can we understand the dynamics of the human heart in terms of the interactions of its cells? No, because the behaviour of every cell depends on the overall state of the heart itself. Causality works in both directions, bottom-up and top-down, at once. What happens cannot be understood by studying any one level on its own.

The book will be a terrific resource for anyone who wants to learn about cutting-edge research into creating artificial cells or other aspects of synthetic biology, or in areas such as epigenetics, where the old gene-centric point of view has been more or less completely undermined.

These ideas have helped drive complexity science forward over the past few decades. Indeed, Capra and Luisi argue that the 21st-century zeitgeist is changing from one of world-as-machine to world-as-network, a holistic system in precise interrelation rather than a collection of dissociated parts. That sounds fine in theory, but how can we put it to use?

“The 21st-century zeitgeist is changing from one of world-as-machine to world-as-network”

This is the focus of the third and final broad section of the book: on sustaining the web of life. Here, Capra and Luisi make some fairly routine observations, for example, that our success will require a shift to more sustainable kinds of economic growth, and finding ways to organise our activities in a manner that doesn’t interfere with nature’s inherent ability to support life.

Ideas like these are hardly new, and that could also be said of much of the book, especially its discussion of systems theory, complexity science, ecology and the roots of our global problems. But this is a broad synthesis, linking many areas of science to make one very important point: that there’s very little we can do without holistic thinking, despite the obvious difficulties involved in doing it well. We are, they suggest, not “ecologically literate” or systems literate, and these are languages we will have to learn.

“We are not ecologically literate or systems literate: these are languages we will have to learn”

As in The Tao of Physics, there is some Eastern mysticism in this book, and rightly so. After all, those philosophies have always emphasised the deep dependence of everything human on nature and the environment, and have taught living with nature rather than trying to dominate it.

We should have been listening long ago. I hope that Capra and Luisi will manage to persuade many that we must start listening now – or face the consequences of our own ignorance.

This article appeared in print under the headline “The Tao of Systems”

Does the idea of parallel universes really describe reality? (Image: NASA/JPL-Caltech/S. Stolovy (Spitzer Science Center/Caltech)

In Our Mathematical Universe Max Tegmark tries hard to make the seemingly outlandish theories of multiverses sound almost obvious and unavoidable

SOME years ago, the philosopher David Hull wrote a book entitled , in which he argued that science works through an evolutionary process. Imaginative scientists toss out ideas and hypotheses, creating and maintaining the equivalent of natural variation in biological populations. Then other scientists test those ideas, using evidence and logic to select out and eliminate the ones that don’t measure up. Variation and selection, repeated: that’s a form of evolution.

But there is a condition. This only works properly with a diversity of personalities and specialisms among scientists. Research would get nowhere if it were driven solely by the dour, hard-boiled sceptics who only believe on the basis of solid evidence. The sceptics feed off the raw creative material of the speculators, who imagine what might be possible and never stop dreaming about “what if”. The speculators produce the diversity of ideas on which selection can act, and they require, in turn, the discipline of sceptics to stop them from running away into fantasy.

And yet fantasy is the very word that occurs to many – including some physicists – when they hear some of the ideas popular in cosmology, a discipline which aims to answer the big questions about the origins of the universe.

The fantasy trajectory started off gently enough when physicist Alan Guth proposed that many puzzling features of the observable universe – such as the extremely homogeneous distribution of matter within it – would be explained if the universe had undergone a short, early period of rapid expansion, termed inflation. Extremely rapid, as in expanding in volume by a factor of 10⁷⁸ in a time of 10^-30 seconds.

Since then, other inflationary cosmologists have opened the speculative throttle so fully that physicists now talk routinely of such things as an infinitude of parallel universes, or a “multiverse”. In the multiverse, every conceivable world exists, and individuals identical to you and I live out parallel lives in places we cannot have access to.

Is this still science? Or has inflationary cosmology veered towards something akin to religion? Some physicists wonder. The enthusiasts, of course, see it very differently. Max Tegmark, a physicist at the Massachusetts Institute of Technology, certainly does. His new book, Our Mathematical Universe, is an impassioned defence of the theory, especially its implications for parallel universes.

The book is an excellent guide to recent developments in quantum cosmology and the ongoing debate over theories of parallel universes. Tegmark tries hard to make the seemingly outlandish sound almost obvious and unavoidable, and offers a taxonomy to help organise a zoo of imagined parallel universes.

“Max Tegmark tries hard to make the seemingly outlandish sound almost obvious and unavoidable”

As it turns out, the terms parallel universes and multiverse mean many things to different people. But Tegmark’s taxonomy of parallel universes are all, he argues, implied by observed evidence and the laws of physics.

His first set, the Level I Multiverse, refers to an idea that many cosmologists already accept. Rapid early inflation would have created what Tegmark describes as “universe-sized parts of space so far away from us that light from them hasn’t had time to reach us”. These other domains – or “universes” – could well exist, although we currently have no observational evidence for them.

Tegmark’s Level II Multiverse refers to a bolder idea, championed by physicist Alexander Vilenkin and others. There may be other domains of space also created by inflation that are too far away to see. These will forever remain out of our reach because continuing inflation drives them from us faster than the speed of light. This idea refers to real, distinct, physical universes that cannot ever be observed.

At this point in the taxonomy, however, Tegmark leaves cosmology behind. In reading, I began to feel that his aim is to see parallel universes in as many places as he can. Enter the Level III Multiverse. This turns out to be a language for talking about the mathematics of quantum theory using the many worlds interpretation of that theory, first proposed by physicist Hugh Everett in the 1950s.

This interpretation describes all physical processes as part of an ongoing, perpetual branching of the universe into many other universes. It is indeed possible to interpret quantum theory this way, but readers should know that many other interpretations, equally in tune with observations, don’t invoke the idea of parallel universes at all.

Then there is the Level IV Multiverse. Again, this has nothing to do with cosmology, but is an ambitious thought about mathematics. Tegmark argues that reality isn’t simply described by mathematics, as most physicists readily accept, but that it is, in fact, mathematical.

“Reality isn’t simply described by mathematics, as physicists accept, but is, in fact, mathematical”

Furthermore, he believes that the mathematics of our universe is just one of an infinity of conceivable mathematical structures. He goes on to wonder: if this mathematical structure is a universe, why not all the others? And so he makes a bold claim – that all other mathematical structures should also exist physically as further parallel universes.

Of course, we don’t really know. The history of science ought to have taught us that just because something sounds unbelievable, it doesn’t mean it is. Human history, after all, is one long progression of people being surprised by what they previously thought was impossible. Isolated tribes learned of other islands and continents, and of the other peoples living there, for example. In modern times we learned of other planets, galaxies, clusters of galaxies and so on. Why not universes? It might even feel quite natural for our universe to just be one of many, especially in the sense of the Level I Multiverse.

Even so, there does seem to be something a little questionable with this vast multiplication of multiverses. While the notion of the Level I Multiverse at least makes contact with real physics and possible evidence, it isn’t clear that any of these other ideas ever could. Multiverse champions seem quite happy, even eager, to invoke infinite numbers of other universes as mechanisms for explaining things we see in our own universe. In a sense, multiverse enthusiasts take a “leap of faith” every bit as big as the leap to believing in a creator, as physicist Paul Davies put it in an .

In the end, this isn’t science so much as philosophy using the language of science. “Inflation”, Tegmark notes, “is the gift that keeps on giving, because every time you think it can’t possibly predict something more radical than it already has, it does.”

This quote is a good example of Tegmark as a creative, speculating scientist, churning out radical ideas as rapidly as possible. It suggests that prediction alone is the point and measure of science, whether or not those predictions turn out to be true.

But all writers overstate their position on occasion, and uninhibited speculation is only one side of Tegmark’s brand of science. Much of his early work, which built his reputation as a physicist, wasn’t of this kind at all. It was hard, empirical stuff, developing methods for analysing data from large-scale telescope projects to measuring fluctuations in the cosmic microwave background.

Perhaps this book is proof that the two personalities needed for science – the speculative and sceptic – can readily exist in one individual.

Read more: “Quantum logic could make better robot bartenders“

The fuzziness and weird logic of the way particles behave applies surprisingly well to how humans think

THE quantum world defies the rules of ordinary logic. Particles routinely occupy two or more places at the same time and don’t even have well-defined properties until they are measured. It’s all strange, yet true – quantum theory is the most accurate scientific theory ever tested and its mathematics is perfectly suited to the weirdness of the atomic world.

Yet that mathematics actually stands on its own, quite independent of the theory. Indeed, much of it was invented well before quantum theory even existed, notably by German mathematician . Now, it’s beginning to look as if it might apply to a lot more than just quantum physics, and quite possibly even to the way people think.

Human thinking, as many of us know, often fails to respect the principles of classical logic. We make systematic errors when reasoning with probabilities, for example. Physicist , has shown that these errors actually make sense within a wider logic based on quantum mathematics. The same logic also seems to fit naturally with how people link concepts together, often on the basis of loose associations and blurred boundaries. That means search algorithms based on quantum logic could uncover meanings in masses of text more efficiently than classical algorithms.

It may sound preposterous to imagine that the mathematics of quantum theory has something to say about the nature of human thinking. This is not to say there is anything quantum going on in the brain, only that “quantum” mathematics really isn’t owned by physics at all, and turns out to be better than classical mathematics in capturing the fuzzy and flexible ways that humans use ideas. “People often follow a different way of thinking than the one dictated by classical logic,” says Aerts. “The mathematics of quantum theory turns out to describe this quite well.”

It’s a finding that has kicked off a burgeoning field known as “quantum interaction”, which explores how quantum theory can be useful in areas having nothing to do with physics, ranging from human language and cognition to biology and economics. And it’s already drawing researchers to .

One thing that distinguishes quantum from classical physics is how probabilities work. Suppose, for example, that you spray some particles towards a screen with two slits in it, and study the results on the wall behind (see diagram). Close slit B, and particles going through A will make a pattern behind it. Close A instead, and a similar pattern will form behind slit B. Keep both A and B open and the pattern you should get – ordinary physics and logic would suggest – should be the sum of these two component patterns.

But the quantum world doesn’t obey. When electrons or photons in a beam pass through the two slits, they act as waves and produce an interference pattern on the wall. The pattern with A and B open just isn’t the sum of the two patterns with either A or B open alone, but something entirely different – one that varies as light and dark stripes.

Such interference effects lie at the heart of many quantum phenomena, and find a natural description in Hilbert’s mathematics. But the phenomenon may go well beyond physics, and one example of this is the violation of what logicians call the “sure thing” principle. This is the idea that if you prefer one action over another in one situation – coffee over tea in situation A, say, when it’s before noon – and you prefer the same thing in the opposite situation – coffee over tea in situation B, when it’s after noon – then you should have the same preference when you don’t know the situation: that is, coffee over tea when you don’t know what time it is.

Remarkably, people don’t respect this rule. In the early 1990s, for example, psychologists Amos Tversky and Eldar Shafir of Princeton University tested the idea in a simple gambling experiment. Players were told they had an even chance of winning $200 or losing $100, and were then asked to choose whether or not to play the same gamble a second time. When told they had won the first gamble (situation A), 69 per cent of the participants chose to play again. If told they had lost (situation B), only 59 per cent wanted to play again. That’s not surprising. But when they were not told the outcome of the first gamble (situation A or B), only 36 per cent wanted to play again.

Classical logic would demand that the third probability equal the average of the first two, yet it doesn’t. As in the double slit experiment, the simultaneous presence of two parts, A and B, seems to lead to some kind of weird interference that spoils classical probabilities.

Flexible logic

Other experiments show similar oddities. Suppose you ask people to put various objects, such as an ashtray, a painting and a sink, into one of two categories: “home furnishings” and “furniture”. Next, you ask if these objects belong to the combined category “home furnishings or furniture”. Obviously, if “ashtray” or “painting” belongs in home furnishings, then it certainly belongs in the bigger, more inclusive combined category too. But many experiments over the past two decades document what psychologists call the disjunction effect – that people often place things in the first category, but not in the broader one. Again, two possibilities listed simultaneously lead to strange results.

These experiments demonstrate that people aren’t logical, at least by classical standards. But quantum theory, Aerts argues, offers richer logical possibilities. For example, two quantum events, A and B, are described by so-called probability amplitudes, alpha and beta. To calculate the probability of A happening, you must square this amplitude alpha and likewise to work out the probability of B happening. For A or B to happen, the probability amplitude is alpha plus beta. When you square this to work out the probability, you get the probability of A (alpha squared) plus that of B (beta squared) plus an additional amount – an “interference term” which might be positive or negative.

This interference term makes quantum logic more flexible. In fact, Aerts has shown that many results demonstrating the disjunction effect fit naturally within a model in which quantum interference can play a role. The way we violate the sure thing principle can be similarly explained with quantum interference, according to economist of Indiana University in Bloomington and psychologist . “Quantum probabilities have the potential to provide a better framework for modelling human decision making,” says Busemeyer.

The strange links go beyond probability, Aerts argues, to the realm of quantum uncertainty. One aspect of this is that the properties of particles such as electrons do not exist until they are measured. The experiment doing the measuring determines what properties an electron might have.

Hilbert’s mathematics includes this effect by representing the quantum state of an electron by a so-called “state vector” – a kind of arrow existing in an abstract, high-dimensional space known as Hilbert space. An experiment can change the state vector arrow, projecting it in just one direction in the space. This is known as contextuality and it represents how the context of a specific experiment changes the possible properties of the electron being measured.

The meaning of words, too, changes according to their context, giving language a “quantum” feel. For instance, you would think that if a thing, X, is also a Y, then a “tall X” would also be a “tall Y” – a tall oak is a tall tree, for example. But that’s not always the case. A chihuahua is a dog, but a tall chihuahua is not a tall dog; “tall” changes meaning by virtue of the word next to it. Likewise, the way “red” is defined depends on whether you are talking about “red wine”, “red hair”, “red eyes” or “red soil”. “The structure of human conceptual knowledge is quantum-like because context plays a fundamental role,” says Aerts.

These peculiar similarities also apply to how search engines retrieve information. Around a decade ago, computer scientists , Pennsylvania, and Rijsbergen of the University of Glasgow, UK, realised that the mathematics they had been building into search engines was essentially the same as that of quantum theory.

Quantum leaps

It didn’t take long for them to find they were on to something. An urgent challenge is to get computers to find meaning in data in much the same way people do, says Widdows. If you want to research a topic such as the “story of rock” with geophysics and rock formation in mind, you don’t want a search engine to give you millions of pages on rock music. One approach would be to include “-songs” in your search terms in order to remove any pages that mention “songs”. This is called negation and is based on classical logic. While it would be an improvement, you would still find lots of pages about rock music that just don’t happen to mention the word songs.

Widdows has found that a negation based on quantum logic works much better. Interpreting “not” in the quantum sense means taking “songs” as an arrow in a multidimensional Hilbert space called semantic space, where words with the same meaning are grouped together. Negation means removing from the search pages that shares any component in common with this vector, which would include pages with words like music, guitar, Hendrix and so on. As a result, the search becomes much more specific to what the user wants.

“It seems to work because it corresponds more closely to the vague reasoning people often use when searching for information,” says Widdows. “We often rely on hunches, and traditionally, computers are very bad at hunches. This is just where the quantum-inspired models give fresh insights.”

That work is now being used to create entirely new ways of retrieving information. Widdows, working with Trevor Cohen at the University of Texas in Houston, and others, has shown that quantum operations in semantic Hilbert spaces are a powerful means of finding previously unrecognised associations between concepts. This may even offer a .

To demonstrate how it might work, the researchers started with 20 million sets of terms called “object-relation-object triplets”, which , had earlier extracted from a . These triplets are formed from pairs of medical terms that frequently appear in scientific papers, such as “amyloid beta-protein” and “Alzheimer’s disease”, linked by any verb that means “associated with”.

The researchers then create a multi-dimensional Hilbert space with state vectors representing the triplets and applied quantum mathematics to find other state vectors that, loosely speaking, point in the same direction. These new state vectors represent potentially meaningful triplets not actually present in the original list. Their approach makes “logical leaps” or informed hypotheses about pairs of terms, which are outside the realms of classic logic but seem likely promising avenues for further study. “We’re aiming to augment scientists’ own mental associations with associations that have been learned automatically from the biomedical literature,” says Cohen.

He and his colleagues then asked medical researchers to use the approach to generate hypotheses and associations beyond what they could come up with on their own. One of them, molecular biologist , used it to explore the biology of the vitamin D receptor and its role in the pathogenesis of cancer. It suggested a possible link between a gene called ncor-1 and the vitamin D receptor, something totally unexpected to Kerr Whitfield, but now the focus of experiments in his lab.

Yet one big question remains: why should quantum logic fit human behaviour? at Queensland University of Technology in Brisbane, Australia, suggests the reason is to do with our finite brain being overwhelmed by the complexity of the environment yet having to take action long before it can calculate its way to the certainty demanded by classical logic. Quantum logic may be more suitable to making decisions that work well enough, even if they’re not logically faultless. “The constraints we face are often the natural enemy of getting completely accurate and justified answers,” says Bruza.

This idea fits with the views of some psychologists, who argue that strict classical logic only plays a small part in the human mind. Cognitive psychologist , for example, argues that much of our thinking operates on a largely unconscious level, where thought follows a less restrictive logic and forms loose associations between concepts.

Aerts agrees. “It seems that we’re really on to something deep we don’t yet fully understand.” This is not to say that the human brain or consciousness have anything to do with quantum physics, only that the mathematical language of quantum theory happens to match the description of human decision-making.

Perhaps only humans, with our seemingly illogical minds, are uniquely capable of discovering and understanding quantum theory. To be human is to be quantum.

“It seems that we’re really on to something deep we don’t yet fully understand”

What can you do with a quarter of an hour? Write a few emails, cook rice – or store antimatter.

The team working on the (ALPHA) at the CERN particle physics laboratory near Geneva, Switzerland, have stored atoms of antihydrogen for 1000 seconds – roughly 10,000 times longer than before. This should help reveal if antimatter and matter are true mirror images.

Antihydrogen atoms are annihilated by hydrogen. The ALPHA team want to keep antimatter intact long enough to study it, so last year they worked out how to hold a cloud of antihydrogen in a magnetic trap. Not for long, though: collisions with trace gases would have either annihilated the anti-atoms or given them the energy to escape, so the team opened the trap after 170 milliseconds and observed the resulting annihilations, verifying that antimatter had been made.

Now they have repeated the experiment, this time waiting much longer before opening the trap. They also cooled the antiprotons used to create the antihydrogen much further, which lowered the energy of the antimatter, allowed more to be squeezed into the trap and raised the chance that some would last longer ().

Antimatter’s life extension will permit experiments, such as checking whether antihydrogen occupies the same energy levels as hydrogen, “perhaps within the next few years”, says of the Illinois Institute of Technology in Chicago, who is not on the ALPHA team.

IT’S midnight in New York when the first computer worm breaches security in the electrical grid serving the city. Within seconds the city plunges into cold darkness, and as the worm continues its attack, directing a crippling surge of power southward, generators and power lines explode and the grid across the eastern US is destroyed. Simultaneously, other worms wreak havoc on strategic points in the grid in Texas, California and Ohio, bringing down the entire US power supply.

This scenario of a terrorist or military attack on a nation’s critical infrastructure is increasingly realistic, particularly in the wake of the Stuxnet computer attack on Iranian nuclear facilities last year.

The electrical grid is just one of the systems at risk: the air transport network, the banking system and even the internet itself are all vulnerable too.

It doesn’t have to be that way, say Christian Schneider, a physicist at the Swiss Federal Institute of Technology in Zurich and his colleagues. According to their model, large technological networks can be greatly improved just by making minor changes that would multiply the paths along which information can flow.

Many real-world networks are surprisingly vulnerable when key components fail. For example, a study of the so-called point-of-presence (PoP) network – the physical servers and routers used by service providers like Virgin or Comcast – found that linkage within the network would fall by 90 per cent if only 12 per cent of the providers failed.

“Linkage within the internet network would fall by 90 per cent if only 12 per cent of service providers failed”

Schneider’s team used a computer model to study how rewiring a network might affect this result. They chose two links at random and switched their end points, then tested this altered network by shutting down certain points, as in an attack. If it was no more resilient than before, they ignored this rewiring and switched two different links instead. When they found an improvement the altered network was taken as the starting point and the process continued. In the real world, the equivalent would be rerouting power transmission or internet traffic.

The results showed that even a few changes can help a lot (Proceedings of the National Academy of Sciences, ). For example, the PoP model became 25 per cent more resilient with a change of only 2 per cent of its links. “We were surprised by how much improvement we saw,” says Schneider. “Even single changes can have a huge positive effect.”

Schneider is not exactly sure why the improvement arises but believes it could be because some changes eliminate hidden bottlenecks – portions of the network where information has to flow through one key element or link. An increase in the number of alternative paths connecting any two points means that the network remains more highly connected even when some key spots get taken out.

“This represents a significant step towards a better understanding of how vital networks can be better protected against malicious attacks,” says physicist Hernan Makse of the City University of New York.

Although Schneider and his colleagues are yet to put their ideas into practice on a real-world network, they expect their insights will be used to do so. “We have found that even a single change in the European power grid – in northern Italy close to the border with Switzerland – could improve grid resilience by 15 per cent,” Schneider notes.

Many subatomic particles act like tiny magnets, with their strength dubbed their “g-factor”. Prior attempts to measure the proton’s g-factor were not precise as they were restricted to probing protons in atoms, where orbiting electrons disguise the proton’s properties.

Now physicists led by at the University of Mainz in Germany have managed to isolate a single proton and measure its g-factor. They start by shooting electrons at a substance: the impact releases protons, which can be trapped using a magnet. Next, the researchers slowly let the protons escape until just one is left. The magnet causes the lone proton to “precess” like a spinning top, at a frequency that depends on its g-factor. The researchers deduced this frequency using radio waves that flipped the orientation of the proton’s magnet only when their frequency matched the precession frequency ().

This in itself did not yield a more precise value for the g-factor than previously, but it will if the proof-of-principle experiment is repeated using a higher-precision trap, says , a team member from the Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany.

The technique could also be used to measure the g-factor of antiprotons. It is thought that antimatter is a mirror image of matter – exactly the same but with an opposite charge. If this is true, then the g-factors of the proton and antiproton should be identical.

Has ET evolved to be discreet? An evolutionary tendency for inconspicuous aliens would solve a nagging paradox – and also suggest that we Earthlings should think twice before advertising our own existence.

As physicist Enrico Fermi argued in 1950, unless the evolution of life is unique to Earth, there must be many intelligent species out there. So why have they neither phoned home nor been detected by us?

“It’s a real paradox,” says of the Perimeter Institute in Waterloo, Ontario, Canada.

In order to explain the Fermi paradox, Kent turns to natural selection – and suggests that it may favour quiet aliens.

Violent universe

He argues that it’s plausible that there is a competition for resources on a cosmic scale, driving an evolutionary process between alien species on different planets. Advanced species, for example, might want to exploit other planets for their own purposes.

If so, the universe would be a violent place, and evolutionary selection may favour the inconspicuous – those who lie low on purpose, or who simply lack the skill or ambition to venture forth or advertise their existence.

“This is an interesting idea,” says alien hunter Seth Shostak of the SETI institute in Mountain View, California. “If I let the cosmos know I exist, then I might be subject to extermination.”

However, he is wary of assuming a “straitjacket” on the activities of intelligent species, who might not be able to resist the intellectual pull to develop advanced technologies detectable by others.

“If interstellar violence is possible, the bad news is that all societies are required to constrain their endeavours to activities that could never be detected at a distance,” says Shostak.

Voyager danger

The theory joins a long list of attempts to explain the Fermi paradox, from the suggestion that aliens’ communications are indistinguishable from background noise, to calculations concluding that ET just hasn’t had enough time to find us.

Kent acknowledges that his hypothesis is speculative. But he also warns that it could have real consequences for the near future: vehicles such as NASA’s two Voyager probes, which are hurtling away from the solar system, may alert imperialist aliens to our existence and require retrieval, he says.

He adds that it may not take much for a truly advanced civilisation to wipe us out pretty quickly. “The hyper-advanced aliens might not have to send their interstellar battle fleet to conquer Earth,” he notes. “It might only take three bored undergraduate aliens with borrowed lab equipment.”

Reference:

AS OUR ancestors moved north out of Africa and onto the doorstep to the rest of the world, they came across their long-lost cousins: the Neanderthals. As the popular story goes, the brutish hominins were simply no match for cultured, intelligent Homo sapiens and quickly went extinct.

Maybe, but it’s also possible that Neanderthals were simply unlucky and disappeared by chance, mathematicians propose.

We know that humans and Neanderthals got pretty cosy during their time together in the Middle East, 45,000 years ago. Between 1 and 4 per cent of the DNA of modern non-Africans is of Neanderthal origin, implying their ancestors must have interbred before humans moved into Europe (żěè¶ĚĘÓƵ, 15 May 2010, p 8).

The popular theory has it that humans soon displaced Neanderthals thanks to their superior skills and adaptations. But mathematicians Armando Neves at the Federal University of Minas Gerais in Belo Horizonte, Brazil, and Maurizio Serva at the University of Aquila, Italy, now say that the extinction of Neanderthals may have been down to a genetic lottery.

When two populations interbreed, one of them can go extinct simply due to the random mixing of their genes through sexual reproduction.

To find out if this could have wiped out Neanderthals, Neves and Serva modelled the populations that met in the Middle East. Using very few assumptions, they estimated the rate of interbreeding that would lead to the observed share of Neanderthal DNA.

Their results suggest that the 1 to 4 per cent genetic mix could have come about with one interbreeding every 10 to 80 generations. The time taken to reach this mix would depend on the size of the populations. But regardless of populations, Neves and Serva’s model shows that low rates of interbreeding could theoretically have led to the extinction of Neanderthals through a genetic lottery ().

“The observed low fraction of Neanderthal DNA could easily have arisen quite naturally even if Neanderthals weren’t inferior,” says Neves.

A strong point of the analysis, says anthropologist Luke Premo of Washington State University in Pullman, is that it makes few assumptions about unknown factors, including the relative sizes of the African and Neanderthal populations at the time.

Nevertheless, says Premo, the evidence for some kind of superiority of the African group is still strong. “Humans were expanding while Neanderthals were fairly restricted to a portion of Eurasia,” he says. “Given their larger population and expansion, it appears that humans were bound to win out.”

When this article was first posted, it gave the wrong university affiliation for Luke Premo.