Tag: Higgs boson

• Worlds between theory and experiment

  Once Isaac Newton showed that a single gravitational law plus his rules of dynamics could reproduce the orbits of planets that Johannes Kepler had predicted, explain tides on Earth, and predict that a comet that had passed by once would return again, physicists considered Newtonian mechanics and gravitation to have been completely validated. After these successful tests, they didn’t wait to test every other possible prediction of Newton’s ideas before they considered them to be legitimate.

  When Jean Perrin and others carefully measured Brownian motion and extracted Avogadro’s number in the early 20th century, they helped cement the science of the kinetic theory of gases and statistical mechanics that Ludwig Boltzmann and Josiah Willard Gibbs had developed. As with Newtonian mechanics, physicists didn’t also require every single consequence of kinetic theory to be rechecked from scratch. They considered them all to be fully and equally legitimate then on.

  Similarly, in 1886-1889, Heinrich Hertz produced and detected electromagnetic waves in the laboratory, measured their speed and other physical properties, and showed that they behaved exactly as James Clerk Maxwell had predicted based on his (famous) equation. Hertz’s experiments didn’t test every possible configuration of charges and fields that Maxwell’s equations allowed, yet what they did test and confirm sufficed to convince all physicists that Maxwell’s theory could be treated as the correct classical theory of electromagnetism.

  In all these cases, a theory won broad acceptance after scientists validated only a small (yet robust) subset of its predictions. They didn’t have to validate every single prediction in distinct experiments.

  However, there are many ideas in high-energy particle physics that, even as they are derived from other theoretical constructs that have been tested to extreme precision, physicists insist on testing them anew as well. Why are they going to this trouble now?

  “High-energy particle physics” is a four-word label for something you’ve likely already heard of: the physics of the search for the subatomic particles like the Higgs boson and the efforts to identify their properties.

  In this enterprise, many scientific ideas follow from theories that have been validated by very large amounts of experimental data. Yet physicists want to test them at every single step because of the way such theories are built and the way unknown effects can hide inside their structures.

  The overarching theory that governs particle physicists is called, simply, the Standard Model. It’s a quantum field theory, i.e. a theory that combines the precepts of quantum mechanics and special relativity*. Because the Standard Model is set up in this way, it makes predictions about the relations between different observable quantities, e.g. the mass of a subatomic particle called the W boson with a parameter that’s related to the decay of other particles called muons. Some of these relations connect measured quantities with others that have not yet been probed, e.g. the mass of the muon with the rate at which Higgs bosons decay to pairs of muons. (Yes, it’s all convoluted.) These ‘extra’ relations often depend on assumptions that go beyond the domains that experiments have already explored. New particles and new interactions between them can change particular parts of the structure while leaving other parts nearly unchanged.

  (* Quantum field theory gives physicists a single, internally consistent framework in which they can impose both the rules of quantum theory and the requirements of special relativity, such as that information or matter can’t travel faster than light and that our spacetime conserves energy and momentum together, for example. However, quantum field theory does not unify quantum theory with general relativity; that’s the monumental and still unfinished purpose of the quantum gravity problem.)

  For a more intricate example, consider the gauge sector of the Standard Model, i.e. the parts of the Model involving the gluons, W and Z bosons, and photons, their properties, and their interactions with other particles. The gauge sector has been thoroughly tested in experiments and is well-understood. Now, the gauge sector also interacts with the Higgs sector, and the Higgs sector interacts with other sectors. The result is new possibilities involving the properties of the Higgs boson, their implications for the gauge sector, and so on that — even if physicists have tested the gauge sector — need to be tested separately. The reason is that none of these possibilities follow directly from the basic principles of the gauge sector.

  The search for ‘new physics’ also drives this attitude. ‘New physics’ refers to measurable entities and physical phenomena that lie beyond what the Standard Model can currently describe. For instance, most physicists believe a substance called dark matter exists (in order to explain some anomalous observations about the universe), but they haven’t been able to confirm what kind of particles dark matter is made of. One popular proposal is that dark matter is made of hitherto unknown entities called weakly interacting massive particles (WIMPs). The Standard Model in its contemporary form doesn’t have room for WIMPs, so the search for WIMPs is a search for new physics.

  Physicists have also proposed many ways to ‘extend’ the Standard Model to accommodate new kinds of particles that ‘repair’ the cracks in reality left by the existing crop of particles. Some of these extensions predict changes to the Model that are most pronounced in sectors that are currently poorly pinned down by existing data. This means even a sizeable deviation from the Model’s structure in this sector would still be compatible with all current measurements. This is another important reason physicists want to collect more data and with ever-greater precision.

  Earlier experience also plays an important role. Physicists may make some assumptions because they seem safe in some year but new data collected in the next two decades might reveal that they were mistaken. For instance, physicists believed neutrinos didn’t have mass, like photons, because that idea was consistent with many existing datasets. Yet dedicated experiments contradicted their belief (and won their performers the 2015 physics Nobel Prize).

  (Aside: High-energy particle physics uses large machines called particle colliders to coerce subatomic particles into configurations where they interact with each other, then collect data of those interactions. Operating these instruments demands hundreds of people working together, using sophisticated technologies and substantial computing resources. Because the instruments are so expensive, these collaborations aim to collect as much data as possible, then maximise the amount of information they extract from each dataset.)

  Thus, when a theory like the Standard Model predicts a specific process, that process becomes a thing to test. But even if the prediction seems simple or obvious, actually measuring it can still rule out whole families of rival theories offering to explain the same process. It also sharpens physicists’ estimates of the theory’s basic parameters, which then makes other predictions more precise and helps plan the next round of experiments. This is why, in high-energy physics, even predictions that follow from other, well-tested parts of a theory are expected to face experimental tests of their own. Each successful test can reduce the space for new physics to hide in — or in fact could reveal it.

  A study published in Physical Review Letters on December 3 showcases a new and apt example of testing predictions made by a theory some of whose other parts have already survived testing. Tests at the Large Hadron Collider (LHC) — the world’s largest, most powerful particle collider — had until recently only weakly constrained the Higgs boson’s interaction with second-generation leptons (a particle type that includes muons). The new study provides strong, direct evidence for this coupling and significantly narrows that gap.

  The LHC operates by accelerating two beams of protons in opposite directions to nearly the speed of light and smashing them head on. Its operation is divided into segments called ‘runs’. Between runs, the collaboration that manages the machine conducts maintenance and repair work and, sometimes, upgrades its detectors.

  One of the LHC’s most prominent detectors is named ATLAS. To probe the interactions between Higgs bosons and leptons, the ATLAS collaboration collected and analysed data from the LHC’s run 2 and run 3. The motivation was to obtain direct evidence for Higgs bosons’ coupling to muons and to measure its strength. And in the December 3 paper, the collaboration reported that the coupling parameters were consistent with the Standard Model’s predictions.

  So that’s one more patch of the Standard Model that has passed a test, and one more door to ‘new physics’ that has closed a little more.

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  Featured image: A view of the Large Hadron Collider inside its tunnel. Credit: CERN.

  2025.12.06

• Is the Higgs boson doing its job?

  At the heart of particle physics lies the Standard Model, a theory that has stood for nearly half a century as the best description of the subatomic realm. It tells us what particles exist, how they interact, and why the universe is stable at the smallest scales. The Standard Model has correctly predicted the outcomes of several experiments testing the limits of particle physics. Even then, however, physicists know that it’s incomplete: it can’t explain dark matter, why matter dominates over antimatter, and why the force of gravity is so weak compared to the other forces. To settle these mysteries, physicists have been conducting very detailed tests of the Model, each of which has either tightened their confidence in a hypothetical explanation or has revealed a new piece of the puzzle.

  A central character in this story is a subatomic particle called the W boson — the carrier of the weak nuclear force. Without it, the Sun wouldn’t shine because particle interactions involving the weak force are necessary for nuclear fusion to proceed. W bosons are also unusual among force carriers: unlike photons (the particles of light), they’re massive, about 80-times heavier than a proton. This mass difference — of a massless photon and a massive W boson — arises due to a process called the Higgs mechanism. Physicists first proposed this mechanism in 1964 and confirmed it was real when they found the Higgs boson particle at the Large Hadron Collider (LHC) in 2012.

  

  But finding the Higgs particle was only the beginning. To prove that the Higgs mechanism really works the way the theory says, physicists need to check its predictions in detail. One of the sharpest tests involves how W bosons scatter off each other at high energies. The key to achieving this is the W boson’s polarisation states. Both photons and W bosons have a property called quantum spin, but whereas for photons its value is zero, for W bosons its non-zero. The spin also has a direction. If it points sideways, the W boson is said to be transverse polarised; if it’s pointing along the particle’s direction of travel, the W boson is said to be longitudinally polarised. The longitudinal ones are special because their behaviour is directly tied to the Higgs mechanism.

  Specifically, if the Higgs mechanism and the Higgs boson don’t exist, calculations involving the longitudinal W bosons scattering off of each other quickly give rise to nonsensical mathematical results in the theory. The Higgs boson acts like a regulator in this engine, preventing the mathematics from ‘blowing up’. In fact, in the 1970s, the theoretical physicists Benjamin Lee, Chris Quigg, and Hugh Thacker showed that without the Higgs boson, the weak force would become uncontrollably powerful at high energies, leading to the breakdown of the theory. Their work was an important theoretical pillar that justified building the colossal LHC machine to search for the Higgs boson particle.

  https://withspeak.wpcomstaging.com/2025/06/24/technical-foundation-for-a-muon-collider-laid-at-j-parc/

  The terms Higgs boson, Higgs field, and Higgs mechanism describe related but distinct ideas. The Higgs field is a kind of invisible medium thought to fill all of space. Particles like W bosons and Z bosons interact with this field as they move and through that interaction they acquire mass. This is the Higgs mechanism: the process by which particles that would otherwise be massless become heavy.

  The Higgs boson is different: it’s a particle that represents a vibration or a ripple in the Higgs field, just as a photon is a ripple in the electromagnetic field. Its discovery in 2012 confirmed that the field is real and not just something that appears in the mathematics of the theory. But discovery alone doesn’t prove the mechanism is doing everything the theory demands. To test that, physicists need to look at situations where the Higgs boson’s balancing role is crucial.

  The scattering of longitudinally polarised W bosons is a good example. Without the Higgs boson, the probabilities of the scatterings occurring uncontrollably at higher energy, but with the Higgs boson in the picture, they stay within sensible bounds. Observing longitudinally polarised W bosons behaving as predicted is thus evidence for the particle as well as a check on the field and the mechanism behind it.

  Imagine a roller-coaster without brakes. As it goes faster and faster, there’s nothing to stop it from flying off the tracks. The Higgs mechanism is like the braking system that keeps the ride safe. Observing longitudinally polarised W bosons in the right proportions is equivalent to checking that the brakes actually work when the roller-coaster speeds up.

  

  Another path that physicists once considered and that didn’t involve a Higgs boson at all was called technicolor theory. Instead of a single kind of Higgs boson giving the W bosons their mass, technicolor proposed a brand-new force. Just as the strong nuclear force binds quarks into protons and neutrons, the hypothetical technicolor force would bind new “technifermion” particles into composite states. These bound states would mimic the Higgs boson’s job of giving particles mass, while producing their own new signals in high-energy collisions.

  The crucial test to check whether some given signals are due to the Higgs boson or due to technicolor lies in the behaviour of longitudinally polarised W bosons. In the Standard Model, their scattering is kept under control by the Higgs boson’s balancing act. In technicolor, by contrast, there is no Higgs boson to cancel the runaway growth. The probability of the scattering of longitudinally polarised W bosons would therefore rise sharply with more energy, often leaving clearly excessive signals in the data.

  Thus, observing longitudinally polarised W bosons at consistent with the predictions of the Standard Model, and not finding any additional signals, would also strengthen the case for the Higgs mechanism and weaken that for technicolor and other “Higgs-less” theories.

  At the Large Hadron Collider, the cleanest way to study look for such W bosons is in a phenomenon called vector boson scattering (VBS). In VBS, two protons collide and the quarks inside them emit W bosons. These W bosons then scatter off each other before decaying into lighter particles. The leftover quarks form narrow sprays of particles, or ‘jets’, that fly far forward.

  If the two W bosons happen to have the same electric charge — i.e. both positive or both negative — the process is even more distinctive. This same-sign WW scattering is quite rare and that’s an advantage because then it’s easy to spot in the debris of particle collisions.

  Both ATLAS and CMS, the two giant detectors at the LHC, had previously observed same-sign WW scattering without breaking down the polarisation. In 2021, the CMS detector reported the first hint of longitudinal polarisation but at a statistical significance only of 2.3 sigma, which isn’t good enough (particle physicists prefer at least 3 sigma). So after the LHC completed its second run in 2018, collecting data from around 10 quadrillion collisions between protons, the ATLAS collaboration set out to analyse it and deliver the evidence. This group’s study was published in Physical Review Letters on September 10.

  

  The challenge of finding longitudinally polarised W bosons is like finding a particular needle in a very large haystack where most of the needles look nearly identical. So ATLAS designed a special strategy.

  When one W boson decays, the result is one electron or muon and one neutrino. If the W boson is positively charged, for example, the decay could be to one anti-electron and one electron-neutrino or to one anti-muon and a muon-neutrino. Anti-electrons and anti-muons are positively charged. If the W boson is negatively charged, the products could one electron and one electron-antineutrino or one muon and one muon-antineutrino. So first, ATLAS zeroed in on the fact that it was looking for two electrons, two muons, or one of each, both carrying the same electric charge. Neutrinos however are really hard to catch and study, so the ATLAS group look for their absence rather than their presence. In all these particle interactions, the law of conservation of momentum holds — which means in a given interaction, a neutrino’s presence can be elucidated when the momenta of the electrons or muons add up to be slightly lower than that of the W boson; the missing amount would have been carried away by the neutrino, like money unaccounted for in a ledger.

  This analysis also required an event of interest to have at least two jets (reconstructed from streams of particles) with a combined energy above 500 GeV and separated widely in rapidity (which is a measure of their angle relative to the beam). This particular VBS pattern — two electrons/muons, two jets, and missing momentum — is the hallmark of same-sign WW scattering.

  Second, even with these strict requirements, impostors creep in. The biggest source of confusion is WZ production, a process in which another subatomic particle called the Z boson decays invisibly or one of its decay products goes unnoticed, making the event resemble WW scattering. Other sources include electrons having their charges mismeasured, jets can masquerading as electrons/muons, and some quarks producing electrons/muons that slip into the sample. To control for all this noise, the ATLAS group focused on control regions: subsets of events that produced a distinct kind of noise that the group could cleanly ‘subtract’ from the data to reveal same-sign WW scattering, thus also reducing uncertainty in the final results.

  Third, and this is where things get nuanced: the differences between transverse and longitudinally polarised W bosons show up in distributions — i.e. how far apart the electrons/muons are in angle, how the jets are oriented, and the energy of the system. But since no single variable could tell the whole story, the ATLAS group combined them using deep neural networks. These machine-learning models were fed up to 20 kinematic variables — including jet separations, particle angles, and missing momentum patterns — and trained to distinguish between three groups:

  (i) Two transverse polarised W bosons;

  (ii) One transverse polarised W boson and one longitudinally polarised W boson; and

  (iii) Both longitudinally polarised W bosons

  Fourth, the group combined the outputs of these neural networks and fit with a maximum likelihood method. When physicists make measurements, they often don’t directly see what they’re measuring. Instead, they see data points that could have come from different possible scenarios. A likelihood is a number that tells them how probable the data is in a given scenario. If a model says “events should look like this,” they can ask: “Given my actual data, how likely is that?” And the maximum likelihood method will help them decide the parameters that make the given data most likely to occur.

  For example, say you toss a coin 100 times and get 62 heads. You wonder: is the coin fair or biased? If it’s fair, the chance of exactly 62 heads is small. If the coin is slightly biased (heads with probability 0.62), the chance of 62 heads is higher. The maximum likelihood estimate is to pick the bias, or probability of heads, that makes your actual result most probable. So here the method would say, “The coin’s bias is 0.62” — because this choice maximises the likelihood of seeing 62 heads out of 100.

  In their analysis, the ATLAS group used the maximum likelihood method to check with the LHC data ‘preferred’ a contribution from longitudinal scattering, after subtracting what background noise and transverse-only scattering could explain.

  The results are a milestone in experimental particle physics. In the September 10 paper, ATLAS reported evidence for longitudinally polarised W bosons in same-sign WW scattering with a significance of 3.3 sigma — sufficiently close to 4, which is the calculated significance based on the predictions of the Standard Model. This means the data behaved as theory predicted, with no unexpected excess or deficit.

  It’s also bad news for technicolor theory. By observing longitudinal W bosons at exactly the rates predicted by the Standard Model, and not finding any additional signals, the ATLAS data strengthens the case for the Higgs mechanism providing the check on the W bosons’ scattering probability, rather than the technicolor force.

  The measured cross-section for events with at least one longitudinally polarised W boson was 0.88femtobarns, with an uncertainty of 0.3 femtobarns. These figures essentially mean that there were only a few hundred same-sign WW scattering events in the full dataset of around 10 quadrillion proton-proton collisions. The fact that ATLAS could pull this signal out of such a background-heavy environment is a testament to the power of modern machine learning working with advanced statistical methods.

  The group was also able to quantify the composition of signals. Among others:

  1. About 58% of events were genuine WW scattering
  2. Roughly 16% were from WZ production
  3. Around 18% arose from irrelevant electrons/muons, charge misidentification or the decay of energetic photons

  One way to appreciate the importance of these findings is by analogy: imagine trying to hear a faint melody being played by a single violin in the middle of a roaring orchestra. The violin is the longitudinal signal; the orchestra is the flood of background noise. The neural networks are like sophisticated microphones and filters, tuned to pick out the violin’s specific tone. The fact that ATLAS couldn’t only hear it but also measured its volume to match the score written by the Standard Model is remarkable.

  Perhaps in the same vein, these results are more than just another tick mark for the Standard Model. It’s a direct test of the Higgs mechanism in action. The discovery of the Higgs boson particle in 2012 was groundbreaking but proving that the Higgs mechanism performs its theoretical role requires demonstrating that it regulates the scattering of W bosons. By finding evidence for longitudinally polarised W bosons at the expected rate, ATLAS has done just that.

  The results also set the stage for the future. The LHC is currently being upgraded to a form called the High-Luminosity LHC and it will begin operating later this decade, collect datasets about 10x larger than what the LHC did in its second run. With that much more data, physicists will be able to study differential distributions, i.e. how the rate of longitudinal scattering varies with energy, angle or jet separation. These patterns are sensitive to hitherto unknown particles and forces, such as additional Higgs-like particles or modifications to the Higgs mechanism itself. That is, even small deviations from the Standard Model’s predictions could hint at new frontiers in particle physics.

  Indeed, history has often reminded physicists that such precision studies often uncover surprises. Physicists didn’t discover neutrino oscillations by finding a new particle but by noticing that the number of neutrinos arriving from the Sun at detectors on Earth didn’t match expectations. Similarly, minuscule mismatches between theory and observations in the scattering of W bosons could someday reveal new physics — and if they do, the seeds will have been planted by studies like that of the ATLAS group.

  https://withspeak.wpcomstaging.com/2025/09/06/challenging-the-neutrino-signal-anomaly/

  On the methodological front, the analysis also showcases how particle physics is evolving. ‘Classical’ analyses once banked on tracking single variables; now, deep learning has played a starring role by combining many variables into a single discriminant, allowing ATLAS to pull the faint signal of longitudinally polarised W bosons from the noise. This approach could only become more important as both datasets and physicists’ ambitions expand.

  Perhaps the broadest lesson in all this is that science often advances by the unglamorous task of verifying the details. The discovery of the Higgs boson answered one question but opened many others; among them, measuring how it affects the scattering of W bosons is one of the ore direct ways to probe whether the Standard Model is complete or just the first chapter of a longer story. Either way, the pursuit exemplifies the spirit of checking, rechecking, testing, and probing until scientists truly understand how nature works at extreme precision.

  Featured image: The massive mural of the ATLAS detector at CERN painted by artist Josef Kristofoletti. The mural is located at the ATLAS Experiment site and shows on two perpendicular walls the detector with a collision event superimposed. The event on the large wall shows a simulation of an event that would be recorded in ATLAS if a Higgs boson was produced. The cavern of the ATLAS Experiment with the detector is 100 m directly below the mural. The height of the mural is about 12 m. The actual ATLAS detector is more than twice as big. Credit: Claudia Marcelloni, Michael Barnett/CERN.

  2025.09.12

• You’re allowed to be interested in particle physics

  This page appeared in The Hindu’s e-paper today.

  

  I wrote the lead article, about why scientists are so interested in an elementary particle called the top quark. Long story short: the top quark is the heaviest elementary particle, and because all elementary particles get their masses by interacting with Higgs bosons, the top quark’s interaction is the strongest. This has piqued physicists’ interest because the Higgs boson’s own mass is peculiar: it’s more than expected and at the same time poised on the brink of a threshold beyond which our universe as we know it wouldn’t exist. To explain this brinkmanship, physicists are intently studying the top quark, including measuring its mass with more and more precision.

  It’s all so fascinating. But I’m well aware that not many people are interested in this stuff. I wish they were and my reasons follow.

  There exists a sufficiently healthy journalism of particle physics today. Most of it happens in Europe and the US, (i) where famous particle physics experiments are located, (ii) where there already exists an industry of good-quality science journalism, and (iii) where there are countries and/or governments that actually have the human resources, funds, and political will to fund the experiments (in many other places, including India, these resources don’t exist, rendering the matter of people contending with these experiments moot).

  In this post, I’m using particle physics as itself as well as as a surrogate for other reputedly esoteric fields of study.

  This journalism can be divided into three broad types: those with people, those concerned with spin-offs, and those without people. ‘Those with people’ refers to narratives about the theoretical and experimental physicists, engineers, allied staff, and administrators who support work on particle physics, their needs, challenges, and aspirations.

  The meaning of ‘those concerned with spin-offs’ is obvious: these articles attempt to justify the money governments spend on particle physics projects by appealing to the technologies scientists develop in the course of particle-physics work. I’ve always found these to be apologist narratives erecting a bad expectation: that we shouldn’t undertake these projects if they don’t also produce valuable spin-off technologies. I suspect most particle physics experiments don’t because they are much smaller than the behemoth Large Hadron Collider and its ilk, which require more innovation across diverse fields.

  ‘Those without people’ are the rarest of the lot — narratives that focus on some finding or discussion in the particle physics community that is relatively unconcerned with the human experience of the natural universe (setting aside the philosophical point that the non-human details are being recounted by human narrators). These stories are about the material constituents of reality as we know it.

  When I say I wish more people were interested in particle physics today, I wish they were interested in all these narratives, yet more so in narratives that aren’t centred on people.

  Now, why should they be concerned? This is a difficult question to answer.

  I’m concerned because I’m fascinated with the things around us we don’t fully understand but are trying to. It’s a way of exploring the unknown, of going on an adventure. There are many, many things in this world that people can be curious about. It’s possible there are more such things than there are people (again, setting aside the philosophical bases of these claims). But particle physics and some other areas — united by the extent to which they are written off as being esoteric — suffer from more than not having their fair share of patrons in the general (non-academic) population. Many people actively shun them, lose focus when reading about them, and at the same time do little to muster focus back. It has even become okay for them to say they understood nothing of some (well-articulated) article and not expect to have their statement judged adversely.

  I understand why narratives with people in them are easier to understand, to connect with, but none of the implicated psychological, biological, and anthropological mechanisms also encourage us to reject narratives and experiences without people. In other words, there may have been evolutionary advantages to finding out about other people but there have been no disadvantages attached to engaging with stories that aren’t about other people.

  Next, I have met more than my fair share of people that flinched away from the suggestion of mathematics or physics, even when someone offered to guide them through understanding these topics. I’m also aware researchers have documented this tendency and are attempting to distil insights that could help improve the teaching and the communication of these subjects. Personally I don’t know how to deal with these people because I don’t know the shape of the barrier in their minds I need to surmount. I may be trying to vault over a high wall by simplifying a concept to its barest features when in fact the barrier is a low-walled labyrinth.

  Third and last, let me do unto this post what I’m asking of people everywhere, and look past the people: why should we be interested in particle physics? It has nothing to offer for our day-to-day experiences. Its findings can seem totally self-absorbed, supporting researchers and their careers, helping them win famous but otherwise generally unattainable awards, and sustaining discoveries into which political leaders and government officials occasionally dip their beaks to claim labels like “scientific superpower”. But the mistake here is not the existence of particle physics itself so much as the people-centric lens through which we insist it must be seen. It’s not that we should be interested in particle physics; it’s that we can.

  Particle physics exists because some people are interested in it. If you are unhappy that our government spends too much on it, let’s talk about our national R&D expenditure priorities and what the practice, and practitioners, of particle physics can do to support other research pursuits and give back to various constituencies. The pursuit of one’s interests can’t be the problem (within reasonable limits, of course).

  More importantly, being interested in particle physics and in fact many other branches of science shouldn’t have to be justified at every turn for three reasons: reality isn’t restricted to people, people are shaped by their realities, and our destiny as humans. On the first two counts: when we choose to restrict ourselves to our lives and our welfare, we also choose to never learn about what, say, gravitational waves, dark matter, and nucleosynthesis are (unless these terms turn up in an exam we need to pass). Yet all these things played a part in bringing about the existence of Earth and its suitability for particular forms of life, and among people particular ways of life.

  The rocks and metals that gave rise to waves of human civilisation were created in the bellies of stars. We needed to know our own star as well as we do — which still isn’t much — to help build machines that can use its energy to supply electric power. Countries and cultures that support the education and employment of people who made it a point to learn the underlying science thus come out on top. Knowing different things is a way to future-proof ourselves.

  Further, climate change is evidence humans are a planetary species, and soon it will be interplanetary. Our own migrations will force us to understand, eventually intuitively, the peculiarities of gravity, the vagaries of space, and (what is today called) mathematical physics. But even before such compulsions arise, it remains what we know is what we needn’t be afraid of, or at least know how to be afraid of. 😀

  Just as well, learning, knowing, and understanding the physical universe is the foundation we need to imagine (or reimagine) futures better than the ones ordained for us by our myopic leaders. In this context, I recommend Shreya Dasgupta’s ‘Imagined Tomorrow’ podcast series, where she considers hypothetical future Indias in which medicines are tailor-made for individuals, where antibiotics don’t exist because they’re not required, where clean air is only available to breathe inside city-sized domes, and where courtrooms use AI — and the paths we can take to get there.

  Similarly, with particle physics in mind, we could also consider cheap access to quantum computers, lasers that remove infections from flesh and tumours from tissue in a jiffy, and communications satellites that reduce bandwidth costs so much that we can take virtual education, telemedicine, and remote surgeries for granted. I’m not talking about these technologies as spin-offs, to be clear; I mean technologies born of our knowledge of particle (and other) physics.

  At the biggest scale, of course, understanding the way nature works is how we can understand the ways in which the universe’s physical reality can or can’t affect us, in turn leading the way to understanding ourselves better and helping us shape more meaningful aspirations for our species. The more well-informed any decision is, the more rational it will be. Granted, the rationality of most of our decisions is currently only tenuously informed by particle physics, but consider if the inverse could be true: what decisions are we not making as well as we could if we cast our epistemic nets wider, including physics, biology, mathematics, etc.?

  Consider, even beyond all this, the awe astronauts who have gone to Earth orbit and beyond have reported experiencing when they first saw our planet from space, and the immeasurable loneliness surrounding it. There are problems with pronouncements that we should be united in all our efforts on Earth because, from space, we are all we have (especially when the country to which most of these astronauts belong condones a genocide). Fortunately, that awe is not the preserve of spacefaring astronauts. The moment we understood the laws of physics and the elementary constituents of our universe, we (at least the atheists among us) may have realised there is no centre of the universe. In fact, there is everything except a centre. How grateful I am for that. For added measure, awe is also good for the mind.

  It might seem like a terrible cliché to quote Oscar Wilde here — “We are all in the gutter, but some of us are looking at the stars” — but it’s a cliché precisely because we have often wanted to be able to dream, to have the simple act of such dreaming contain all the profundity we know we squander when we live petty, uncurious lives. Then again, space is not simply an escape from the traps of human foibles. Explorations of the great unknown that includes the cosmos, the subatomic realm, quantum phenomena, dark energy, and so on are part of our destiny because they are the least like us. They show us what else is out there, and thus what else is possible.

  If you’re not interested in particle physics, that’s fine. But remember that you can be.

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  Featured image: An example of simulated data as might be observed at a particle detector on the Large Hadron Collider. Here, following a collision of two protons, a Higgs boson is produced that decays into two jets of hadrons and two electrons. The lines represent the possible paths of particles produced by the proton-proton collision in the detector while the energy these particles deposit is shown in blue. Caption and credit: Lucas Taylor/CERN, CC BY-SA 3.0.

  2024.07.02

• Looking (only) for Nehru

  I have a habit of watching one old Tamil film a day. Yesterday evening, I was watching a film released in 1987, called Ivargal Indiyargal (‘They Are Indians’). In a scene in the film, an office manager distributes sweets to his colleagues. One of them takes a look at the item and asks the manager if he bought it from a particular shop that was famous for such items. The manager takes umbrage and scolds his colleague that he’s been asking that question for too many years, and demands to know if no other good sweet shop has opened since.

  An innocuous scene in an innocuous film, yet it seemed to have a parallel with the Chandrayaan-3 mission. On August 23, as I’m sure you’re aware, the mission’s robotic lander module touched down in the moon’s south polar region, rendering India the first country to achieve this feat. It was a moment worth celebrating without any reservations, yet soon after, the social media commentariat had found a way – admittedly not difficult – to make it part of its relentlessly superficial avalanche of controversy and dissension. One vein of it was of course split along the lines of what Jawaharlal Nehru did or didn’t do to help ISRO in its formative years. (The Hindu also received some letters from readers to this effect.)

  But more than right-wing nuts trying to rewrite history in order to diminish the influence of Nehru’s ideals on modern India, I find the counter-argument to be curious and, sometimes, worth some concern. The rebuttals frequently take the form that we must remember Nehru in this time, the idea of scientific temper with which he was so taken, the “importance of science” for India’s development, the virtues of Nehruvian secularism, and so forth. It seems to be a reflex to leap all the way back to the first 16 years after independence, always at the cost of many more variants of all these ideals, often refined or revised to better accommodate the pressures of development, modernisation, and globalisation. (See here for one example.)

  Members of the Congress party are partly to blame: sometimes they seem incapable of commemorating an event in terms other than that Nehru set the stage for them many years ago. BJP nationalists have also displayed a similar tendency. For example, in 2013, after Peter Higgs and François Englert were awarded the physics Nobel Prize for predicting the existence of the Higgs boson, the nationalists demanded that the laureates should have honoured Satyendra Nath Bose, whose work laid the foundation for the study of all bosons, and that the ‘b’ in ‘boson’ should always be capitalised. It was a ridiculous ask that was disinterested in work that had built on Bose’s ideas and papers in the intervening years, and also betrayed a failure to understand how really a scientist and thinker of Bose’s calibre ought to be honoured, more than capitalising little letters.

  Similarly, today, the full weight of Nehru’s legacy is invoked even to counter arguments as rudimentary as chest-thumping. To quote the office manager in Ivargal Indiyargal, has there been no other articulation of the same impulses? My concern about this frankly insensible habit to reach for Nehru is threefold: first, it will overlook other ideas from other individuals grounded in different lived experiences (especially those of marginalisation); second, the moments in which he is invoked are conducive to glazing over the problems, found only upon a closer look, with what Nehru and for that matter Vikram Sarabhai, Satish Dhawan, and others stood for; and third, perhaps I’m a fool to look for sense where it has seldom been found.

  2023.08.26

• The gap between language and quantum mechanics

  Physics World has a fantastic article about the problem with using a language invented, in Terry Pratchett’s words, “to tell other monkeys where the ripe fruit is”, to describe the peculiar but very much real possibilities created by the rules of quantum mechanics. Excerpt:

  … despite the burgeoning growth of quantum technology, one thing that hasn’t changed is the cumbersome and counterintuitive language we use to talk about all things quantum. While the reality of entanglement and superposition is beyond all reasonable doubt, it is as maddening as ever to describe them in words. Quantum phenomena are strange, but that does not mean we should be satisfied with strange language to describe them.

  From the very early days of quantum mechanics, Albert Einstein, Niels Bohr, Werner Heisenberg and others strove to understand this new-fangled non-classical physics of quantum 1.0. Their struggle concerned a gap between how we talk about phenomena and how we encounter them in the laboratory. That gap was created by the imperfect metaphorical language still largely used to characterize non-classical phenomena.

  The authors have written that the terms that writers, journalists, and scientists reach for when describing quantum phenomena to people who don’t have the mathematical awareness (for want of a better description) are probably adding to the confusion instead of clarifying quantum mechanics, and diminishing its realness. ‘Superposition’ is a good example: it’s a word that captures a particular phenomenon, but when you try to spell it out, in toto with no exceptions, to someone who doesn’t understand the math of it, you use some metaphors and approximations that either create an incomplete picture or an obscured one. And both add to quantum physics’s mystery and spookiness, which are counterproductive.

  This has been a familiar challenge in my experience covering high-energy physics as well, were the protagonists are often particles and forces that are best described using mathematical grammar (amplitudes, matrices, groups, etc.) rather than the language that facilitates everyday life. This is why I think the molasses metaphor (and minor variations of it) may well have been the most used of its kind in 2012, when the Higgs boson, and its corresponding energy field, dominated physics news: in the New York Times‘s words, “What is the Higgs field? … It has been described as a kind of cosmic molasses, dragging on particles as they move through it”. In an instructive 2013 paper, Stewart Alsop and Steven Beale wrote (emphasis in the original) about the problems with such metaphors:

  At some point, of course, all analogical thinking breaks down—the Higgs phenomena is not a crowd or molasses. Perhaps a weakness with these analogies is their reliance on a ‘medium’ as the object node mapped to the Higgs field. This is probably unavoidable, but it results in a number of points of potential confusion. The concept of a medium is generally understood to be a volume filled with a physical substance that can be manipulated and controlled. This is not the case in the standard model of the Higgs field, which is understood to be uniform and constant. The familiar conception of a medium is insufficient to fully understand the Higgs field in this respect. A medium can be entered and exited because it is localized, it can be concentrated in one location and minimized in another, and it is composed of matter and has its own mass and energy. Mapping these attributes onto the Higgs field leads to a line of reasoning reminiscent of 19th century aether theories.

  Obviously metaphors aren’t going to be perfect. That’s almost always the case. Instead, they’re handy because they capture a particularly interesting subset of something larger, more complicated, and get that across by drawing on things a person is already familiar with, like, of course, molasses. Through history, this has progressively become harder to do, and scientists themselves have taken note of it from time to time. For example, Werner Heisenberg delivered a speech in 1932, while receiving the Nobel Prize for physics, in which he pointed out the need to discard visualisation or, more accurately, visualisability as a means to unravelling the pending mysteries of atomic physics. He said it quite eloquently, so let me quote him:

  … the path so far traced by the quantum theory indicates that an understanding of those still unclarified features of atomic physics can only be acquired by foregoing visualization and objectification to an extent greater than that customary hitherto. We have probably no reason to regret this, because the thought of the great epistemological difficulties with which the visual atom concept of earlier physics had to contend gives us the hope that the abstracter atomic physics developing at present will one day fit more harmoniously into the great edifice of Science.

  This said, metaphors and analogies vis-à-vis quantum mechanics (getting quantum computing right took considerable effort, for a famous example) have become particularly problematic because this field of study has created technologies that are beginning to enter the public consciousness at large. There is now a greater price to pay by misunderstanding, for example, that quantum teleportation refers to bulk matter, as in Star Trek, rather than to information or, in fact, that entanglement is in Albert Einstein’s words “spooky action at a distance”. But it’s not spooky; it’s just something we don’t have the language for.

  But quantum mechanics and its consequent technologies don’t have a monopoly on being shortchanged by imprecise communication. Climate change is in the same boat. There is also another kind of price that has already been paid across the vast majority of science: a widespread belief among certain (sadly prevalent) groups of people that they understand science when they really don’t, leading to an inflated belief in the abilities and importance of science while overlooking our tendency to confuse faith for truly knowing something. (I have written about this before here, here, and here, among other instances.)

  Finally, the question of the gaps between language as we use it and quantum mechanics is reminiscent of a plot point in China Miéville’s Embassytown, where people designated “ambassadors” can only speak in pairs, simultaneously: each ambassador utters a different word-meaning, and their alien interlocutors combine the duo’s words-meanings to understand what they’re saying. In the book, these two word-meanings are written like a fraction – one word on top, a line in the middle, and the other at the bottom. But thanks to Miéville’s prose, we know that that’s only a partial representation of what’s really going on in the story. We come upon a relatable sensation in the film Arrival.

  Embassytown was a gratifying read that delved into the relationships between language and storytelling as much as between a language, its grammar, and its symbols. Like good fantasy fiction, it steadily yet gently dismantles the cognitive dissonance that reality sometimes foists on us – in this case, that would be cognising why English or for that matter any linear human language will always fall short of describing true simultaneity.

  One workaround, according to the Physics World article above, is that rather than trying to bend our language around the barely tractable and math-laden processes of quantum mechanics, we should describe the field in terms of its outcomes. To know more, do read the article.

  2023.04.27

• The Higgs boson and I

  My first byline as a professional journalist (a.k.a. my first byline ever) was oddly for a tech story – about the advent of IPv6 internet addresses. I started writing it after 7 pm, had to wrap it up by 9 pm and it was published in the paper the next day (I was at The Hindu).

  The first byline that I actually wanted to take credit for appeared around a month later, on July 4, 2012 – ten years ago – on the discovery of the Higgs boson at the Large Hadron Collider (LHC) in Europe. I published a live blog as Fabiola Gianotti, Joe Incandela and Rolf-Dieter Heuer, the spokespersons of the ATLAS and CMS detector collaborations and the director-general of CERN, respectively, announced and discussed the results. I also distinctly remember taking a pee break after telling readers “I have to leave my desk for a minute” and receiving mildly annoyed, but also amused, comments complaining of TMI.

  After the results had been announced, the science editor, R. Prasad, told me that R. Ramachandran (a.k.a. Bajji) was filing the main copy and that I should work around that. So I wrote a ‘what next’ piece describing the work that remained for physicists to do, including open problems in particle physics that stayed open and the alternative theories, like supersymmetry, required to explain them. (Some jingoism surrounding the lack of acknowledgment for S.N. Bose – wholly justifiable, in my view – also forced me to write this.)

  I also remember placing a bet with someone that the Nobel Prize for physics in 2012 wouldn’t be awarded for the discovery (because I knew, but the other person didn’t, that the nominations for that year’s prizes had closed by then).

  To write about the feats and mysteries of particle physics is why I became a science journalist, so the Higgs boson’s discovery being announced a month after I started working was special – not least because it considerably eased the amount of effort I had to put in to pitches and have them accepted (specifically, I didn’t have to spend too much time or effort spelling out why a story was important). It was also a great opportunity for me to learn about how breaking news is reported as well as accelerated my induction into the newsroom and its ways.

  But my interest in particle physics has since waned, especially from around 2017, as I began to focus in my role as science editor of The Wire (which I cofounded/joined in May 2015) on other areas of science as well. My heart is still with physics, and I have greatly enjoyed writing the occasional article about topological phases, neutrino astronomy, laser cooling and, recently, the AdS/CFT correspondence.

  A couple years ago, I realised during a spell of daydreaming that even though I have stuck with physics, my act of ‘dropping’ particle physics as a specialty had left me without an edge as a writer. Just physics was and is too broad – even if there are very few others in India writing on it in the press, giving me lots of room to display my skills (such as they are). I briefly considered and rejected quantum computing and BECCS technologies – the former because its stories were often bursting with hype, especially in my neck of the woods, and the latter because, while it seemed important, it didn’t sit well morally. I was indifferent towards them because they were centered on technologies whereas I wanted to write about pure, supposedly boring science.

  In all, penning an article commemorating the tenth anniversary of the announcement of the Higgs boson’s discovery brought back pleasant memories of my early days at The Hindu but also reminded me of this choice that I still need to make, for my sake. I don’t know if there is a clear winner yet, although quantum physics more broadly and condensed-matter physics more specifically are appealing. This said, I’m also looking forward to returning to writing more about physics in general, paralleling the evolution of The Wire Science itself (some announcements coming soon).

  I should also note that I started blogging in 2008, when I was still an undergraduate student of mechanical engineering, in order to clarify my own knowledge of and thoughts on particle physics.

  So in all, today is a special day.

  2022.07.04

• US experiments find hint of a break in the laws of physics

  

  At 9 pm India time on April 7, physicists at an American research facility delivered a shot in the arm to efforts to find flaws in a powerful theory that explains how the building blocks of the universe work.

  Physicists are looking for flaws in it because the theory doesn’t have answers to some questions – like “what is dark matter?”. They hope to find a crack or a hole that might reveal the presence of a deeper, more powerful theory of physics that can lay unsolved problems to rest.

  The story begins in 2001, when physicists performing an experiment in Brookhaven National Lab, New York, found that fundamental particles called muons weren’t behaving the way they were supposed to in the presence of a magnetic field. This was called the g-2 anomaly (after a number called the gyromagnetic factor).

  An incomplete model

  Muons are subatomic and can’t be seen with the naked eye, so it could’ve been that the instruments the physicists were using to study the muons indirectly were glitching. Or it could’ve been that the physicists had made a mistake in their calculations. Or, finally, what the physicists thought they knew about the behaviour of muons in a magnetic field was wrong.

  In most stories we hear about scientists, the first two possibilities are true more often: they didn’t do something right, so the results weren’t what they expected. But in this case, the physicists were hoping they were wrong. This unusual wish was the product of working with the Standard Model of particle physics.

  According to physicist Paul Kyberd, the fundamental particles in the universe “are classified in the Standard Model of particle physics, which theorises how the basic building blocks of matter interact, governed by fundamental forces.” The Standard Model has successfully predicted the numerous properties and behaviours of these particles. However, it’s also been clearly wrong about some things. For example, Kyberd has written:

  When we collide two fundamental particles together, a number of outcomes are possible. Our theory allows us to calculate the probability that any particular outcome can occur, but at energies beyond which we have so far achieved, it predicts that some of these outcomes occur with a probability of greater than 100% – clearly nonsense.

  The Standard Model also can’t explain what dark matter is, what dark energy could be or if gravity has a corresponding fundamental particle. It predicted the existence of the Higgs boson but was off about the particle’s mass by a factor of 100 quadrillion.

  All these issues together imply that the Standard Model is incomplete, that it could be just one piece of a much larger ‘super-theory’ that works with more particles and forces than we currently know. To look for these theories, physicists have taken two broad approaches: to look for something new, and to find a mistake with something old.

  For the former, physicists use particle accelerators, colliders and sophisticated detectors to look for heavier particles thought to exist at higher energies, and whose discovery would prove the existence of a physics beyond the Standard Model. For the latter, physicists take some prediction the Standard Model has made with a great degree of accuracy and test it rigorously to see if it holds up. Studies of muons in a magnetic field are examples of this.

  According to the Standard Model, a number associated with the way a muon swivels in a magnetic field is equal to 2 plus 0.00116591804 (with some give or take). This minuscule addition is the handiwork of fleeting quantum effects in the muon’s immediate neighbourhood, and which make it wobble. (For a glimpse of how hard these calculations can be, see this description.)

  Fermilab result

  In the early 2000s, the Brookhaven experiment measured the deviation to be slightly higher than the model’s prediction. Though it was small – off by about 0.00000000346 – the context made it a big deal. Scientists know that the Standard Model has a habit of being really right, so when it’s wrong, the wrongness becomes very important. And because we already know the model is wrong about other things, there’s a possibility that the two things could be linked. It’s a potential portal into ‘new physics’.

  “It’s a very high-precision measurement – the value is unequivocal. But the Standard Model itself is unequivocal,” Thomas Kirk, an associate lab director at Brookhaven, had told Science in 2001. The disagreement between the values implied “that there must be physics beyond the Standard Model.”

  This is why the results physicists announced today are important.

  The Brookhaven experiment that ascertained the g-2 anomaly wasn’t sensitive enough to say with a meaningful amount of confidence that its measurement was really different from the Standard Model prediction, or if there could be a small overlap.

  Science writer Brianna Barbu has likened the mystery to “a single hair found at a crime scene with DNA that didn’t seem to match anyone connected to the case. The question was – and still is – whether the presence of the hair is just a coincidence, or whether it is actually an important clue.”

  So to go from ‘maybe’ to ‘definitely’, physicists shipped the 50-foot-wide, 15-tonne magnet that the Brookhaven facility used in its Muon g-2 experiment to Fermilab, the US’s premier high-energy physics research facility in Illinois, and built a more sensitive experiment there.

  The new result is from tests at this facility: that the observation differs from the Standard Model’s predicted value by 0.00000000251 (give or take a bit).

  The Fermilab results are expected to become a lot better in the coming years, but even now they represent an important contribution. The statistical significance of the Brookhaven result was just below the threshold at which scientists could claim evidence but the combined significance of the two results is well above.

  The Muon g-2 experiment at Fermilab sees fundamental particles called muons behaving in a way not predicted by the Standard Model of particle physics. These results confirm an earlier experiment performed at @BrookhavenLab. #gminus2https://t.co/92KZ5nWzCT pic.twitter.com/eX0ifQcR03

  — Fermilab (@Fermilab) April 7, 2021

  Potential dampener

  So for now, the g-2 anomaly seems to be real. It’s not easy to say if it will continue to be real as physicists further upgrade the Fermilab g-2’s performance.

  In fact there appears to be another potential dampener on the horizon. An independent group of physicists has had a paper published today saying that the Fermilab g-2 result is actually in line with the Standard Model’s prediction and that there’s no deviation at all.

  This group, called BMW, used a different way to calculate the Standard Model’s value of the number in question than the Fermilab folks did. Aida El-Khadra, a theoretical physicist at the University of Illinois, told Quanta that the Fermilab team had yet to check BMW’s approach, but if it was found to be valid, the team would “integrate it into its next assessment”.

  The ‘Fermilab approach’ itself is something physicists have worked with for many decades, so it’s unlikely to be wrong. If the BMW approach checks out, it’s possible according to Quanta that just the fact that two approaches lead to different predictions of the number’s value is likely to be a new mystery.

  But physicists are excited for now. “It’s almost the best possible case scenario for speculators like us,” Gordan Krnjaic, a theoretical physicist at Fermilab who wasn’t involved in the research, told Scientific American. “I’m thinking much more that it’s possibly new physics, and it has implications for future experiments and for possible connections to dark matter.”

  The current result is also important because the other way to look for physics beyond the Standard Model – by looking for heavier or rarer particles – can be harder.

  This isn’t simply a matter of building a larger particle collider, powering it up, smashing particles and looking for other particles in the debris. For one, there is a very large number of energy levels at which a particle might form. For another, there are thousands of other particle interactions happening at the same time, generating a tremendous amount of noise. So without knowing what to look for and where, a particle hunt can be like looking for a very small needle in a very large haystack.

  The ‘what’ and ‘where’ instead come from different theories that physicists have worked out based on what we know already, and design experiments depending on which one they need to test.

  Into the hospital

  One popular theory is called supersymmetry: it predicts that every elementary particle in the Standard Model framework has a heavier partner particle, called a supersymmetric partner. It also predicts the energy ranges in which these particles might be found. The Large Hadron Collider (LHC) in CERN, near Geneva, was powerful enough to access some of these energies, so physicists used it and went looking last decade. They didn’t find anything.

  

  Other groups of physicists have also tried to look for rarer particles: ones that occur at an accessible energy but only once in a very large number of collisions. The LHC is a machine at the energy frontier: it probes higher and higher energies. To look for extremely rare particles, physicists explore the intensity frontier – using machines specialised in generating collisions.

  The third and last is the cosmic frontier, in which scientists look for unusual particles coming from outer space. For example, early last month, researchers reported that they had detected an energetic anti-neutrino (a kind of fundamental particle) coming from outside the Milky Way participating in a rare event that scientists predicted in 1959 would occur if the Standard Model is right. The discovery, in effect, further cemented the validity of the Standard Model and ruled out one potential avenue to find ‘new physics’.

  This event also recalls an interesting difference between the 2001 and 2021 announcements. The late British scientist Francis J.M. Farley wrote in 2001, after the Brookhaven result:

  … the new muon (g-2) result from Brookhaven cannot at present be explained by the established theory. A more accurate measurement … should be available by the end of the year. Meanwhile theorists are looking for flaws in the argument and more measurements … are underway. If all this fails, supersymmetry can explain the data, but we would need other experiments to show that the postulated particles can exist in the real world, as well as in the evanescent quantum soup around the muon.

  Since then, the LHC and other physics experiments have sent supersymmetry ‘to the hospital’ on more than one occasion. If the anomaly continues to hold up, scientists will have to find other explanations. Or, if the anomaly whimpers out, like so many others of our time, we’ll just have to put up with the Standard Model.

  Featured image: A storage-ring magnet at Fermilab whose geometry allows for a very uniform magnetic field to be established in the ring. Credit: Glukicov/Wikimedia Commons, CC BY-SA 4.0.

  The Wire Science
  April 8, 2021

  2021.04.09

• My heart of physics

  Every July 4, I have occasion to remember two things: the discovery of the Higgs boson, and my first published byline for an article about the discovery of the Higgs boson. I have no trouble believing it’s been eight years since we discovered this particle, using the Large Hadron Collider (LHC) and its ATLAS and CMS detectors, in Geneva. I’ve greatly enjoyed writing about particle physics in this time, principally because closely engaging with new research and the scientists who worked on them allowed me to learn more about a subject that high school and college had let me down on: physics.

  In 2020, I haven’t been able to focus much on the physical sciences in my writing, thanks to the pandemic, the lockdown, their combined effects and one other reason. This has been made doubly sad by the fact that the particle physics community at large is at an interesting crossroads.

  In 2012, the LHC fulfilled the principal task it had been built for: finding the Higgs boson. After that, physicists imagined the collider would discover other unknown particles, allowing theorists to expand their theories and answer hitherto unanswered questions. However, the LHC has since done the opposite: it has narrowed the possibilities of finding new particles that physicists had argued should exist according to their theories (specifically supersymmetric partners), forcing them to look harder for mistakes they might’ve made in their calculations. But thus far, physicists have neither found mistakes nor made new findings, leaving them stuck in an unsettling knowledge space from which it seems there might be no escape (okay, this is sensationalised, but it’s also kinda true).

  Right now, the world’s particle physicists are mulling building a collider larger and more powerful than the LHC, at a cost of billions of dollars, in the hopes that it will find the particles they’re looking for. Not all physicists are agreed, of course. If you’re interested in reading more, I’d recommend articles by Sabine Hossenfelder and Nirmalya Kajuri and spiralling out from there. But notwithstanding the opposition, CERN – which coordinates the LHC’s operations with tens of thousands of personnel from scores of countries – recently updated its strategy vision to recommend the construction of such a machine, with the ability to produce copious amounts of Higgs bosons in collisions between electrons and positrons (a.k.a. ‘Higgs factories’). China has also announced plans of its own build something similar.

  Meanwhile, scientists and engineers are busy upgrading the LHC itself to a ‘high luminosity version’, where luminosity represents the number of interesting events the machine can detect during collisions for further study. This version will operate until 2038. That isn’t a long way away because it took more than a decade to build the LHC; it will definitely take longer to plan for, convince lawmakers, secure the funds for and build something bigger and more complicated.

  There have been some other developments connected to the current occasion in terms of indicating other ways to discover ‘new physics’, which is the collective name for phenomena that will violate our existing theories’ predictions and show us where we’ve gone wrong in our calculations.

  The most recent one I think was the ‘XENON excess’, which refers to a moderately strong signal recorded by the XENON 1T detector in Italy that physicists think could be evidence of a class of particles called axions. I say ‘moderately strong’ because the statistical significance of the signal’s strength is just barely above the threshold used to denote evidence and not anywhere near the threshold that denotes a discovery proper.

  It’s evoked a fair bit of excitement because axions count as new physics – but when I asked two physicists (one after the other) to write an article explaining this development, they refused on similar grounds: that the significance makes it seem likely that the signal will be accounted for by some other well-known event. I was disappointed of course but I wasn’t surprised either: in the last eight years, I can count at least four instances in which a seemingly inexplicable particle physics related development turned out to be a dud.

  The most prominent one was the ‘750 GeV excess’ at the LHC in December 2015, which seemed to be a sign of a new particle about six-times heavier than a Higgs boson and 800-times heavier than a proton (at rest). But when physicists analysed more data, the signal vanished – a.k.a. it wasn’t there in the first place and what physicists had seen was likely a statistical fluke of some sort. Another popular anomaly that went the same way was the one at Atomki.

  But while all of this is so very interesting, today – July 4 – also seems like a good time to admit I don’t feel as invested in the future of particle physics anymore (the ‘other reason’). Some might say, and have said, that I’m abandoning ship just as the field’s central animus is moving away from the physics and more towards sociology and politics, and some might be right. I get enough of the latter subjects when I work on the non-physics topics that interest me, like research misconduct and science policy. My heart of physics itself is currently tending towards quantum mechanics and thermodynamics (although not quantum thermodynamics).

  One peer had also recommended in between that I familiarise myself with quantum computing while another had suggested climate-change-related mitigation technologies, which only makes me wonder now if I’m delving into those branches of physics that promise to take me farther away from what I’m supposed to do. And truth be told, I’m perfectly okay with that. 🙂 This does speak to my privileges – modest as they are on this particular count – but when it feels like there’s less stuff to be happy about in the world with every new day, it’s time to adopt a new hedonism and find joy where it lies.

  2020.07.04

• Writing itself is fantasy

  The symbols may have been laid down on paper or the screen in whatever order but when we read, we read the words one at a time, one after another – linearly. Writing, especially of fiction, is an act of using the linear construction of meaning to tell a story whose message will be assimilated bit by bit into a larger whole that isn’t necessarily linear at all, and manages to evade cognitive biases (like the recency effect) that could trick the reader into paying more attention to parts of the story instead of the intangible yet very-much-there whole. Stories in fact come in many shapes. One of my favourites, Dune, is so good because it’s entirely spherical in the spacetime of this metaphor, each of its concepts like a three-dimensional ouroboros, connected end to end yet improbably layered over, under and around each other. The first four Harry Potter books are my least favourite pieces of good fantasy for their staunch linearity, even despite the use of time travel.

  The plot of Embassytown struggles with this idea a little bit, with its fraction-like representation of meaning using pairs of words. Even then, China Miéville has a bit of a climb on his hands: his (human) readers consume the paired words one at a time, first the one on the top then the one on the bottom. So a bit of translation becomes necessary, an exercise in projecting a higher dimensional world in which words are semantically bipolar, like bar magnets each with two ends, onto the linguistic surface of one in which the words are less chimerical. Miéville is forced to be didactic (which he musters with some reluctance), expending a few dozen pages constructing rituals of similes the reader can employ to sync with the Ariekei, the story’s strange alien characters, but always only asymptotically so. We can after all never comprehend a reality that exists in six – or six-thousand – dimensions, much the same way the Higgs boson’s existence is a question of faith if you’re unfamiliar with the underlying mathematics and the same way a human mind and an alien mind can never truly, as they say, connect.

  Arrival elevates this challenge, presenting us with alien creatures – the ‘heptapods’ – the symbols of whose communication are circular, each small segment of the circumference standing for one human word and the whole assemblage for meaning composed by a non-linear combination of words. I’m yet to read the book by Ted Chiang on which the film is based; notwithstanding the possibility that Chiang has discussed their provenance, I wonder if the heptapods think a complex thought that is translated into a clump of biochemical signals that then encode meaning in a stochastic process: not fully predictably, since we know through the simpler human experience that a complicated idea can be communicated using more than one combination of simpler ideas. One heptapod’s choice could easily differ from that of another.

  The one human invention, and experience if you will, that recreates the narrative anxiety encoded in the Ariekei’s and heptapods’ attempts (through their respective authors’ skills, imagination, patience and whatever else) to communicate with humans is writing insofar as the same anxiety manifests in the use of a lower order form – linearity – to construct a higher order image. Thus from the reader’s perspective the writer inhabits an inferior totality, and the latter performs a construction, an assimilation, by synthesising the sphericity and wholeness of a story using fundamentally linear strands, an exercise in building a circle using lines, and using circles to build a sphere, and so forth.

  Writing a story is in effect like convincing someone that an object exists but having no way other than storytelling to realise the object’s existence. Our human eyes will always see the Sun as a circle but we know it’s a sphere because there are some indirect ways to ascertain its sphericity, more broadly to ascertain the universe exists in three dimensions at least locally; the ‘simplest’ of these ways would be to entirely assume the Sun is spherical because that seems to simplify problem-solving. However, say one writer’s conceit is that the Sun really exists in eight dimensions and goes on to construct an elaborate story of adventure, discovery and contemplation to convince the reader that they’re right.

  In this sense, the writer would draw upon our innate knowledge of the universe in three dimensions, and our knowledge and experience of the ways in which it and isn’t truthful, to build an emergent higher-order Thing. While this may seem like a work of science and/or fantasy fiction, the language humans use to build all of their stories, even the nonfiction, renders every act of story-telling a similarly architecturally constructive endeavour. No writer commences narration with the privilege of words meaning more than they stand for in the cosmos of three dimensions and perpetually forward-moving time nor sentences being parsed in any way other than through the straightforward progression of a single stream of words. Everything more complicated than whatever can be assembled with two-dimensional relationships requires a voyage through the fantastic to communicate.

  2020.03.03

• Peter Higgs, self-promoter

  I was randomly rewatching The Big Bang Theory on Netflix today when I spotted this gem:

  

  Okay, maybe less a gem and more a shiny stone, but still. The screenshot, taken from the third episode of the sixth season, shows Sheldon Cooper mansplaining to Penny the work of Peter Higgs, whose name is most famously associated with the scalar boson the Large Hadron Collider collaboration announced the discovery of to great fanfare in 2012.

  My fascination pertains to Sheldon’s description of Higgs as an “accomplished self-promoter”. Higgs, in real life, is extremely reclusive and self-effacing and journalists have found him notoriously hard to catch for an interview, or even a quote. His fellow discoverers of the Higgs boson, including François Englert, the Belgian physicist with whom Higgs won the Nobel Prize for physics in 2013, have been much less media-shy. Higgs has even been known to suggest that a mechanism in particle physics involving the Higgs boson should really be called the ABEGHHK’tH mechanism, include the names of everyone who hit upon its theoretical idea in the 1960s (Philip Warren Anderson, Robert Brout, Englert, Gerald Guralnik, C.R. Hagen, Higgs, Tom Kibble and Gerardus ‘t Hooft) instead of just as the Higgs mechanism.

  No doubt Sheldon thinks Higgs did right by choosing not to appear in interviews for the public or not writing articles in the press himself, considering such extreme self-effacement is also Sheldon’s modus of choice. At the same time, Higgs might have lucked out and be recognised for work he conducted 50 years prior probably because he’s white and from an affluent country, both of which attributes nearly guarantee fewer – if any – systemic barriers to international success. Self-promotion is an important part of the modern scientific endeavour, as it is with most modern endeavours, even if one is an accomplished scientist.

  All this said, it is notable that Higgs was also a conscientious person. When he was awarded the Wolf Prize in 2004 – a prestigious award in the field of physics – he refused to receive it in person in Jerusalem because it was a state function and he has protested Israel’s war against Palestine. He was a member of the Campaign for Nuclear Disarmament until the group extended its opposition to nuclear power as well; then he resigned. He also stopped supporting Greenpeace after they become opposed to genetic modification. If it is for these actions that Sheldon deemed Higgs an “accomplished self-promoter”, then I stand corrected.

  Featured image: A portrait of Peter Higgs by Lucinda Mackay hanging at the James Clerk Maxwell Foundation, Edinburgh. Caption and credit: FF-UK/Wikimedia Commons, CC BY-SA 4.0.

  2020.02.19