Richard Feynman's sister Joan's advice to him: "Imagine you're a student again"

Richard and Joan at the beach

Richard Feynman might have been the most famous Feynman of the twentieth century, but his younger sister Joan - who turned 90 a few days ago -  was no slouch. At a time when it was difficult for women to enter and thrive in science, she became a noted astrophysicist in her own right, investigating stellar nucleosynthesis and the aurora among other topics. By all accounts the two also enjoyed a warm relationship, with Richard encouraging Joan's scientific interests from an early age.

There was one time however when it was Joan who gave Richard a very valuable piece of advice for solving a thorny scientific problem, and not only did it serve him well throughout his future career, but it's also one that all of us can really benefit from. In the 1950s, during the heyday of particle physics, Feynman was at a conference in Rochester where there was word of a profoundly deep potential discovery - so-called 'parity violation'. Parity violation means that left and right are not the same, a fact that seems to go against very fundamental physical laws: for instance, in chemistry there is no a priori reason why the parity or 'handedness' of amino acids should be left instead of right, and most researchers think that the only reason we have left handed amino acids is because of an initial accident that then got perpetuated. And yet there were some unstable particles whose decay into simpler ones seemed to violate parity.

At the conference Feynman read a paper by Chen Ning Yang and Tsung Dao Lee, two Chinese-American physicists who had theoretically showed that parity could be violated in certain ways. At that point in time Feynman was in the middle of a kind of scientific slump. He had made his most famous, Nobel Prize winning discovery - the reformulation of quantum electrodynamics - about ten years earlier, and was looking for fresh scientific questions to ponder. Parity violation seemed exactly like the kind of bold and potentially revolutionary problem that would benefit from an unconventional mind like this. But he felt stuck. At that point Joan came to his rescue. As he writes in his memoirs,

“During the conference I was staying with my sister in Syracuse. I brought the paper home and said to her, “I can’t understand these things that Lee and Yang are saying. It’s all so complicated.”

“No,” she said, “what you mean is not that you can’t understand it, but that you didn’t invent it. You didn’t figure it out your own way, from hearing the clue. What you should do is imagine you’re a student again, and take this paper upstairs, read every line of it, and check the equations. Then you’ll understand it very easily.”

I took her advice, and checked through the whole thing, and found it to be very obvious and simple. I had been afraid to read it, thinking it was too difficult.”

And this was sound advice indeed. Feynman thought hard about parity violation, and along with his 'frenemy' Murray Gell-Mann came up with a theory of beta decay that was one of his most significant contributions to physics (it would be the only paper the two would jointly co-author). He got out of his scientific slump and went on to invent a startlingly original theory of superfluidity. But Joan's advice - for which he deeply thanked her later - was pivotal in getting him started on this path.

The advice may seem obvious, and yet it's something that we often forget once we graduate from college or graduate school and progress in our scientific careers. One of my college professors once offered another related piece of advice: "Nothing's difficult, only unfamiliar". When we are students we are used to actually studying difficult topics and walking through them line by line (perhaps because it's required for the final exam, but nonetheless!). Later somehow we seem to lose the zeal and inclination for sustained, serious study of the kind that we did as eager college students. 

What Joan was telling Richard that it's only prolonged attacks on tough subject material that can yield insights. When you don't invent something - and that applies to most things - you do have to go back to basics and try to understand it from scratch. That approach of taking everything apart and understanding it from a fresh perspective played right into the Feynman playbook; it was what had enabled him to reinvent quantum mechanics. When it came to parity violation the strategy clearly worked for him. And there is no reason why it should not work for lesser mortals. We didn't invent many things, but we can understand most things.

The Higgs boson and the future of science

My latest post on the Scientific American blog network ties together several threads about reductionism, emergence and the nature of scientific problems which I have explored on this blog.

Philip Anderson: Anderson first described the so-called Higgs mechanism and also fired the first modern salvo against strong reductionism (Image: Celeblist)

The discovery of the Higgs boson (or the "Higgs-like particle" if you prefer) is without a doubt one of the signal scientific achievements of our time. It illustrates what sheer thought - aided by data of course - can reveal about the workings of the universe and it continues a trend that lists Descartes, Hume, Galileo and Newton among its illustrious forebears. From sliding objects down an incline to smashing atoms at almost the speed of light in a 27 kilometer tunnel, we have come a long way. Dissecting our origins and the universe around us scarcely gets any better than this.

Yet even as the exciting discovery was being announced, I could not help but think about what the Higgs does not do for us. It does not speed up the time needed to discover a new cancer drug. It does not help us understand consciousness. It does not tell us how life began or whether it exists elsewhere in the universe. It does not explain romantic love, how to design the best solar cell, why people have certain political preferences and how exactly to predict the effects of climate change. In fact we can safely predict that the discovery of the Higgs boson, as consciousness-elevating as it is, does not impact the daily work of 99% of all pure and applied scientists in the world.

I do not say all this to downplay the discovery of the particle which is an unparalleled triumph of human thought, hard work and experimental ingenuity. I also do not say this to make the obvious point that a discovery in one field of science does not automatically solve problems in other fields. Rather, I say this to probe the deeper reality beyond that point, to highlight the multifaceted nature of science and the sheer diversity of problems and phenomena that it presents to us at every level of inquiry. And I say this with a suspicion that the Higgs boson may be the most fitting tribute to the limitations of what has been the most potent philosophical instrument of scientific discovery - reductionism.

In one sense the discovery of this fundamental component of matter can be seen as the culmination of reductionist thinking, accounting as it does for the very existence of mass. Reductionism is the great legacy of the twentieth century, a philosophy whose seeds were sown when Greek philosophers started mulling the nature of matter. The method is in fact quite intuitive; ever since they stepped down from the trees, human beings have tried to solve problems by breaking them down into simpler parts. In the twentieth century the fruits of reductionism have been nothing short of awe-inspiring. Reductionism is what told us that molecules are made of atoms, that the universe is expanding, that DNA is a double helix and that you can build lasers and computers. The reductionist ethic has given us quantum mechanics, relativity, quantum chemistry and molecular biology. Over the centuries it has been used by its countless practitioners as a fine scalpel which has laid bare the secrets of nature. In fact many of the questions answered using the reductionist method were construed as being amenable to this method even before their answers were provided; for instance, how do atoms combine to form molecules? What is the basic nature of the gene? What are atoms themselves made up of?

Yet as we enter the second decade of the twenty-first century, it is clear that reductionism as a principal weapon in our arsenal of discovery tools is no longer sufficient. Consider some of the most important questions facing modern science, almost all of which deal with complex, multifactorial systems. How did life on earth begin? How does biological matter evolve consciousness? What are dark matter and dark energy? How do societies cooperate to solve their most pressing problems? What are the properties of the global climate system? It is interesting to note at least one common feature among many of these problems; they result from the buildup rather than the breakdown of their operational entities. Their signature is collective emergence, the creation of attributes which are greater than the sum of their constituent parts. Whatever consciousness is for instance, it is definitely a result of neurons acting together in ways that are not obvious from their individual structures. Similarly, the origin of life can be traced back to molecular entities undergoing self-assembly and then replication and metabolism, a process that supersedes the chemical behavior of the isolated components. The puzzle of dark matter and dark energy also have as their salient feature the behavior of matter at large length and time scales. Studying cooperation in societies essentially involves studying group dynamics and evolutionary conflict. The key processes that operate in the existence of all these problems seem to almost intuitively involve the opposite of reduction; they all result from the agglomeration of molecules, matter, cells, bodies and human beings across a hierarchy of unique levels. In addition, and this is key, they involve the manifestation of unique principles emerging at every level that cannot be merely reduced to those at the underlying level.

The traditional picture of science asserts that X can be reduced to Y. Reality is more complicated (Image: P. W. Anderson, Science, 1972)

A classic example of emergence: The exact shape of a termite mound is not reducible to the actions of individual termites (Image: Wikipedia Commons)

This kind of emergence has long since been seen as key to the continued unraveling of scientific mysteries. While emergence had been implicitly appreciated by scientists for a long time, its modern salvo was undoubtedly a 1972 paper in Science by the Nobel Prize winning physicist Philip Anderson titled "More is Different", a title that has turned into a kind of clarion call for emergence enthusiasts. In his paper Anderson (who incidentally first came up with the so-called Higgs mechanism) argued that emergence was nothing exotic; for instance, a lump of salt has properties very different from those of its highly reactive components sodium and chlorine. A lump of gold evidences properties like color that don't exist at the level of individual atoms. Anderson also appealed to the process of broken symmetry, invoked in all kinds of fundamental events - including the existence of the Higgs boson - as being instrumental for emergence. Since then, emergent phenomena have been invoked in hundreds of diverse cases, ranging from the construction of termite hills to the flight of birds. The development of chaos theory beginning in the 60s further illustrated how very simple systems could give rise to very complicated and counterintuitive patterns and behavior that are not obvious from the identities of the individual components.

Many scientists and philosophers have contributed to considered critiques of reductionism and an appreciation of emergence since Anderson wrote his paper. These thinkers make the point that not only does reductionism fail in practice (because of the sheer complexity of the systems it purports to explain), but it also fails in principle on a deeper level. In his book "The Fabric of Reality" for instance, the Oxford physicist David Deutsch has made the compelling point that reductionism can never explain purpose; to drive home this point he asks us if it can account for the existence of a particular atom of copper on the tip of the nose of a statue of Winston Churchill in London. Deutsch's answer is a clear no, since the fate of that atom was based on contingent, emergent phenomena, including war, leadership and adulation. Nothing about the structure of copper atoms allows us to directly predict that a particular atom will someday end up on the tip of that nose. Chance plays an outsized role in these developments and reductionism offers us little solace to understand such historical accidents.

Complexity theorist Stuart Kauffman who has written about the role of contingency as a powerful argument against strong reductionism (Image: Wikipedia Commons)

An even more forceful proponent of this contingency-based critique of reductionism is the complexity theorist Stuart Kauffman (supposedly an inspiration for the Jeff Goldblum character in "Jurassic Park") who has laid out his thoughts in two books. Just like Anderson, Kauffman does not deny the great value of reductionism in illuminating our world, but he also points out the factors that greatly limit its application. One of his favorite examples is the role of contingency in evolution and the object of his attention is the mammalian heart. Kauffman makes the case that no amount of reductionist analysis could explain tell you that the main function of the heart is to pump blood. Even in the unlikely case that you could predict the structure of hearts and the bodies that house them starting from the Higgs boson, such a deductive process could never tell you that of all the possible functions of the heart, the most important one is to pump blood. This is because the blood-pumping action of the heart is as much a result of historical contingency and the countless chance events that led to the evolution of the biosphere as it is of its bottom-up construction from atoms, molecules, cells and tissues. As another example, consider the alpha amino acids which make up all proteins on earth. These amino acids come in two potential varieties, left-handed and right-handed. With very few exceptions, all the functional amino acids that we know of are left handed, but there's no reason to think that right handed amino acids wouldn't have served life equally well. The question then is, why left-handed amino acids? Again, reductionism is silent on this question mainly because the original use of left-handed amino acids during the origin of life was to the best of our knowledge a matter of contingency. Now some form of reductionism may still explain the subsequent propagation of left-handed amino acids and their dominance in biological processes by resorting to molecular level arguments regarding chemical bonding and energetics, but this description will still leave the origins issue unresolved. Even something as fundamental as the structure and function of DNA - which by all accounts was a triumph of reductionism - is much better explained by principles of chemistry like electrostatic attraction and hydrogen bonding.

Life as we know it is based on left-handed amino acids. But there is no reason why right-handed amino acids could not sustain life (Image: Islamickorner)

Reductionism then falls woefully short when trying to explain two things; origins and purpose. And one can see that if it has problems even when dealing with left-handed amino acids and human hearts, it would be in much more dire straits when attempting to account for say kin selection or geopolitical conflict. The fact is that each of these phenomena are better explained by fundamental principles operating at their own levels. Chemistry has its covalent bonds and steric effects, geology has its weathering and tectonic shifts, neurology has its memory potentiation and plasticity and sociology has its conflict theory. And as far as we can tell, these sciences will continue to progress without needing the help of Higgs bosons and neutrinos. This also seems to make it unlikely that the discovery of a single elegant equation linking the four fundamental forces (the purported "theory of everything"), while undoubtedly representing one of the greatest intellectual achievements of humanity, will give sociologists and economists little pause for thought, even as they continue to study the stock market and democracies using their own special toolkit of bedrock principles.

This rather gloomy view of reductionism may sound like science is at a dead end or at the very least has started collapsing under the weight of its own success. But such a view would be as misplaced as announcements about the "end of science" which have surfaced every couple of years for the last two hundred years. Every time the end of science has been announced, science itself proved that claims of its demise were vastly exaggerated. Firstly, reductionism will always be alive and kicking since the general approach of studying anything by breaking it down into its constituents will continue to be enormously fruitful. But more importantly, it's not so much the end of reductionism as the beginning of a more general paradigm that combines reductionism with new ways of thinking. The limitations of reductionism should be seen as a cause not for despair but for celebration since it means that we are now entering new, uncharted territory. There are still an untold number of deep mysteries that science has to solve, ranging from dark energy, consciousness and the origin of life to more supposedly pedestrian concerns like superconductivity, cancer drug discovery and the behavior of glasses. Many of these questions require interdisciplinary approaches which result in the crafting of fundamental principles that are unique to the problem statement. Such a meld will inherently involve reductionism only as one component.

Now there are some who may not consider these problems as "fundamental" enough but that is because they would be peering through the lens of traditional twentieth century science. One of the sad casualties of the reductionist undertaking is a small group of people who think that cosmology and particle physics constitute the only things truly worth doing and the epitome of fundamental science; the rest is all detail that can be filled in by second-rate minds. This is in spite of the inconvenient fact that perhaps 80% of physicists are not concerned at all with fundamental questions. But you would be deluding yourself if you are thinking that turbulence in fluids is a second-rate problem (still unsolved) for second-rate minds, especially if you remember that Heisenberg thought that God would will be able to provide an explanation for quantum mechanics but not for turbulence. The fact is that "pedestrian" concerns like superconductivity have engaged some of the best minds of the last fifty years without fully succumbing to them, and at their own levels they are as hard as the discovery of the Higgs boson or the accelerating universe. Exploring these worthy conundrums is every bit as exciting, deep and satisfying as any other endeavor in science. Those who are wondering what's next should not worry; a sparkling journey lies ahead.

To guide us on this journey all we have to remember are the words of one of the twentieth century's great reductionists and one of Peter Higgs's heroes. Paul Dirac closed his famous text on quantum theory with stirrings that will hopefully be as great a portent for the emergent twenty-first century as they were for the reductionist twentieth: "Some new principles are here needed".

References:
1. P. W. Anderson, More is Different, Science, 1972, 177, 393
2. David Deutsch, "The Fabric of Reality", 2004
3. Stuart Kauffman, "Reinventing the Sacred", 2009; "At Home in the Universe", 1996
Other reading:
1. Terrence Deacon, "Incomplete Nature", 2011
2. John Horgan, "The End of Science", 1997
3. Robert Laughlin, "A Different Universe", 2006

What mad pursuit...

These days we are all excited about the Higgs boson, but as Frank Close reminds us in his lucid and comprehensive yet succinct book, the real heroic efforts in particle physics of the twentieth century were in pursuing and hunting down the elusive neutrino. The neutrino is copiously produced by solar processes and every second billions of neutrinos astonishingly pass through our bodies, yet the particle has no charge and for a long time was postulated to have no mass, which made its detection difficult to put it mildly.

Close documents the initial theoretical efforts by Wolfgang Pauli, Enrico Fermi and others to explain atomic processes like beta decay by invoking the neutrino. But the real heroes in the story are the experimentalists who spent their entire careers and gambled their scientific lives in dogged pursuit of this ghost particle. It was Bruno Pontecorvo, a protege of Fermi who realized that one could set up chlorine tanks near nuclear reactors to detect the existence of neutrinos. Pontecorvo also proposed other creative and theoretical ideas to capture and analyze neutrinos. He certainly deserved and would probably have won a Nobel Prize had he lived long enough and not defected to the Soviet Union. After Pontecorvo, the great modern heroes of the neutrino story are Raymond Davis and John Bahcall who spent their lives making heroic efforts to nail down the identity of Fermi's "little neutral one". Davis read Pontecorvo's paper in the early 50s and decided to set up an ambitious experiment with a chlorine tank several kilometers underground in an abandoned mine. The location was necessary to shield out other radiation from cosmic rays and capture only neutrinos, which being massless can travel virtually unimpeded through the earth. At the same time their lack of charge and mass makes their interaction with matter very rare and fleeting. Bahcall was a theoretical wizard who provided increasingly accurate estimates of the rate of capture. Half a century of almost obsessive work by the two men won Davis a Nobel Prize in physics, which he should have shared with Bahcall.

The story also has amusing side-lines, such as when a group of physicists called a nearby nuclear power station to correct their calculations for antineutrinos produced by the reactor. Not knowing what an antineutrino was, the reactor personnel assumed that the particle was harmful and that the physicists were environmentalists, and they tried to assure the scientists that "no antineutrinos were being produced" which would have been impossible and violated some fundamental laws of physics. One of the most intriguing discussions in the book documents the resolution of the so-called "solar neutrino problem". The generation of neutrinos in the processes that produce solar energy had been described by Hans Bethe and others. But the actual rate of detection turned out to be far less than the theoretical postulated rate. Something was missing and this caused a lot of angst for several decades. Bahcall and Davis gambled their entire careers on this paradox. A lot of creative, Nobel Prize caliber work by many scientists involving the decay of other novel particles like muons and pions finally revealed that the neutrinos emitted by the sun were actually changing their identities between two "flavors" called electron and muon neutrinos. This process was termed neutrino oscillation. The underground detectors could detect only one flavor of neutrino, explaining the discrepancy between theory and experiment. It was one of particle physics's resounding triumphs and revealed among other things that neutrinos have a vanishingly small but finite mass.

The tremendous work with neutrinos in the 20th century has led to the flourishing of a branch of astronomy called "neutrino astronomy" in the 21st. The study of the types, numbers, directions and flavors of neutrinos can shed valuable light on astrophysical processes taking place inside exotic objects like supernovas millions of light years away. Some of the facilities set up to detect neutrinos involve football field sized underground detectors filled with hundreds of tons of material located in some of the most extreme environments on the planet like the South Pole in order to avoid interference from other sources. Neutrino astronomy has turned physicists into intrepid explorers traveling to the far reaches of the planet. Their work is ensuring that we now have an additional window into the workings of the farthest and deepest reaches of the cosmos. But as Close excitingly documents in this slim volume, the foundation for all these exciting developments was laid by the theoreticians and experimentalists who participated in some of the most exciting races and pursuits of particle physics during the twentieth century. It's a story that's as rousing as any in science.

Will-o'-the-wisp around 5 sigma: the hunting of the Higgs

Mr. Hunter, we have rules that are not open to interpretation, personal intuition, gut feelings, hairs on the back of your neck, little devils or angels sitting on your shoulder.... - Capt. Ramsey ('Crimson Tide')

Particle physicists hunting for maddeningly elusive particles sometimes must feel like Mr. Hunter in the movie "Crimson Tide". The quarries which they are trying to mine seem so ephemeral, making their presence known in events with such slim probability margins, victims of nature's capricious dance of energy and matter, that intuition must sometimes seem as important as data. The hunt for such particles signifies some of the most intense efforts in extruding reality from nature's womb that human beings have ever put in.

No other particle exemplifies this uniquely human of all endeavors than the so-called Higgs boson. The man who bears the burden of imparting it its name is now a household name himself. Yet as the history of science often demonstrates, the real story is both more interesting and more complicated. It involves intense competition involving billions of dollars and thousands of careers of a kind rarely seen in science, and stories of glories and follies befitting the great tragedies. In his book "Massive", Ian Sample does a marvelous job of bringing this history to life.

Sample excels at three things. The first is the story of the two great laboratories that have mainly been involved in the race to the finish in discovering nature's building blocks- Fermilab and CERN. CERN was started in the 60s to give a boost to European physics after World War 2. Fermilab was lovingly built by the experimental physicist Robert Wilson, a former member of the Manhattan Project who was a first-rate amateur architect and saw accelerators as aesthetic things of beauty. Secondly, Sample does a nice job of explaining the reasons that led to the construction of these machines, the most complicated that mankind has ever constructed. Only human beings would put billions of dollars and immense manpower on the line purely for the purpose of satisfying man's curiosity of plumbing the depths of nature's deepest secrets. Sample also lays out the very human and social concerns that accompany such investigations. Lastly, Sample was lucky enough to get an extended interview with Peter Higgs, a shy man who very rarely does interviews. Higgs grew up in Scotland idolizing Paul Dirac and shared Dirac's view of a unifying beauty that would connect nature's disparate facts. In the late 1960s he wrote papers describing what is now called the Higgs boson. The papers were well-accepted in the US and Higgs's name soon began to be bandied about in seminars and meetings. As described below however, Higgs was not the only one postulating the theory.

So what exactly is the Higgs boson? A complete understanding would naturally need a background in theoretical physics, but the best analogy for the layman was given by a British scientist. Imagine a room full of young women who are happily chatting. In walks a handsome young man. As long as he is not noticed he can move freely across the room, but as soon as the young women spot him they cluster around him, impeding his movement. It's as though the young man has become heavier and has acquired mass from the "field" of women surrounding him. The Higgs then is the particle that imparts specific masses to all the other myriad particles discovered so far including quarks and leptons through its own field. It should be evident why it's important. The Higgs would be the crowning achievement in the Standard Model of particle physics which encompasses all particles and forced known until now except gravity.

However, the history of the Higgs particle is complicated. Sample does a great job of explaining why the credit belongs to six different people who reached the same conclusion that Higgs did. It seems that Higgs was not the first to publish, but he was the first one to clearly state the existence of a new particle. However, the most comprehensive theory of the Higgs field and particle came out later. If Nobel Prizes are to be awarded, it's not at all clear what three people should be picked, although Higgs's name seems obvious. The sociology of scientific discovery is as important as the facts and again illustrates that science is a much more haphazard and random process than is believed.

The search for the Higgs gathered tremendous momentum in the 80s and 90s. It intensified after accelerator laboratories spectacularly discovered two particles named the W and Z bosons that are responsible for mediating the electromagnetic and weak interactions (the electroweak force). These particles were predicted by Steven Weinberg, Abdus Salam and Sheldon Glashow in the 60s, and their prediction surely ranks as one of the greatest theoretical successes in modern physics. Once the theory predicted the masses of these particles, they were up for grabs. No experimentalist worth his or her salt would fail to relish nailing a concrete theoretical prediction of fundamental importance through a decisive experiment. Sample captures the pulse-quickening inter-Atlantic races to find these particles especially between CERN and Fermilab. The importance of these particles was so obvious that Nobel Prizes came in quick succession both to the theorists and the experimentalists. However the existence of the Higgs is also essential for the successful formulation of the electroweak theory, and signatures of the Higgs are thought to be produced whenever W and Z bosons are created. It again becomes obvious why finding the Higgs is so important; its existence would validate all those successes and Nobel Prizes, whereas a failure to find it would entail a stunningly hard look at some of particle physics's most fundamental notions.

These days the Large Hadron Collider (LHC) is all over the news. Yet the most exciting part of Sample's book describes not the LHC but the Large Electron Positron collider (LEP) at CERN which was the largest particle accelerator in the world at the time. Unlike protons, electrons and positrons are fundamental particles and crashing them together produces 'cleaner' results. There were some fascinating events associated with the LEP. The behemoth's circumference was 27 kilometers and it crisscrossed the Swiss-French border, so authorities had to seek permission to build the accelerator underneath some homes. It seems that French law is special just like their cheese and language; apparently if you build a house in France, it means that you own the entire ground beneath the house, all the way to the center of the earth. Suffice it to say that some negotiation with the homeowners was necessary to secure permission for underground construction. At one point the intensity of the beams inside the mammoth machine started to wax and wane. After many days of brainstorming a scientist had a hunch; it turns out that the the gravity of the moon and the sun sets up tides inside the crust of the earth. These tides put the calibration of the machine off by a millimeter, too small to be noticed by human beings, but thunderingly large for electron beams. In another case, the daily departure of a train from a nearby station sent surges of electricity into the ground and affected the beams. It seems like when you are building an accelerator you have to guard against the workings of the entire solar system.

The story of particle physics is also fraught with tragedies. One of the biggest described in the book was the construction of the Superconducting Supercollider in Texas. The SSC was supposed to be the answer to CERN and got enthusiastic backing from Reagan and Bush Sr. Unfortunately the budget spiraled out of hand, the infighting intensified, congressmen remained unconvinced and the collider never got built in spite of spending billions and affecting thousands of careers of scientists who had relocated. The fiasco just proved that public support for even projects like the LHC is never a sure thing, and scientists don't always excel at public relations.

Then of course there are all the doomsday scenarios and concerns which were raised about the LHC, from the formation of black holes to the world ending in myriad other ways. As Sample describes, these concerns go back to an accelerator at Brookhaven National Laboratory which would impact large gold ions together at furious velocities. The would-be Nobel laureate Frank Wilczek raised the theoretical yet vanishingly small probability of forming 'strangelets', entities akin to the fictitious substance 'Ice-9' in Kurt Vonnegut's novel 'Cat's Cradle'. These strangelets would coalesce together matter around themselves and form a superstable form of dead matter that would rapidly engulf the entire planet. The concern about strangelets pales in comparison however to the possibility of 'vacuum decay', in which our universe is thought to be in a perfectly happy but metastable state like a vase on a table. All it takes is a little nudge or a massive kick from a high-energy particle collision in our case to dislodge the vase or universe from its metastable state into a stable state of minimum energy. Gratifyingly, not only would this state mean the end of life as we know it but it would also mean the impossibility of life ever arising. Yes, all these scenarios seem straight out of the drug-induced, overactive imagination of a demented mind, but at least some of them are within the realm of theoretical possibility. Unfortunately when the result is the destruction of the planet, the words "improbable" and "vanishingly small" will never do much to assuage the public's fears. It just indicates that physicists will always have to grapple with public relations issues vastly more complex than the LHC.

Finally, we get a fascinating overview of the kinds of things which scientists hope to see in the LHC. The problem is that the generation of particles like the Higgs is a very low-probability event and is usually only a side-product of some other primary event. The situation is made more complicated by the immense difficulty of observing such fleeting glimpses in a hideously complex background of noise generated by the creation of other particles. Scientists working on these projects have to keep their eyes and instruments peeled for the one in a trillion event that may bring them glory. Whenever an event is observed, the scientists have to calculate the realm of probability in which it belongs. Usually if the event is outside five standard deviations ('5 sigma') then it is extremely likely to be real and not have occurred by chance alone. Not surprisingly, the observation and communication of these events is a tortuous thing. Publicity has to be avoided before you confirm such fleeting bits of probability, but leaks inevitably offer. And the media has seldom shown any restraint in announcing such potentially momentous discoveries which would bring glory, prizes and money to their originators. Scientists working today also have to deal with the presence of blogs and other instant communication conduits. As Sample narrates, at least in one case a physicist at CERN posted preliminary LHC results on the blog Cosmic Variance, and all hell broke loose. Scientists have to tread carefully especially in this era of instant data dissemination.

All this makes the scientists engaged in such endeavors live on the edge, and to us they appear like the explorers who have their eyes peeled to the sky looking out for the stray signal that would announce the presence of extraterrestrials. The mathematics of the Higgs boson is of course much more sound than that of alien contact, but the scientists who are looking for it are hanging on to such flimsy wisps of probability and interpretation that they surely must be questioning their own sanity sometimes.

In the end, even physicists are all too human. As Capt. Ramsey says, our rules are not always subject to little devils and angels sitting on our shoulders. And yet it seems that scientists like the Higgs hunters sometimes would be tempted to trust the hairs on the back of their head, especially when those hairs stand up straight at the glimpse of a peak in the graph, that 5-sigma event which would change everything. Maybe, just maybe.