CERN is proposing a £13 billion collider to succeed the Large Hadron Collider, representing the organization’s next major investment in unraveling the mysteries of the universe. More than 40 years after a book about the lab ignited his curiosity, Mark Thomson now leads CERN as its director general, tasked with charting the future of particle physics at a pivotal moment. Despite the discovery of the Higgs boson, the Standard Model remains incomplete, failing to explain phenomena like dark matter or the imbalance between matter and antimatter. “In a sense, particle physics hasn’t changed since Thomson was a boy: it is dazzling in its outline, but maddening in the details it cannot yet supply,” notes the organization as it prepares to address these lingering questions with a new generation of research.
Higgs Boson Discovery & Its Connection to Particle Mass
The discovery of the Higgs boson in 2012 was a monumental achievement, but it did not deliver a complete picture of reality. Instead, it illuminated the profound gaps in our understanding of the fundamental universe. Mark Thomson notes that the field’s outline remains “dazzling,” yet is hampered by “maddening” details it cannot yet explain, a sentiment echoing the persistent mysteries surrounding particle physics despite decades of progress. The Higgs boson itself is radically different from any other known particle, possessing no spin or electric charge, only mass, a characteristic that potentially links it to several unresolved issues within the standard model. This unique particle’s defining property is the presence of its associated quantum field “everywhere in the universe,” a phenomenon responsible for imparting mass to all other particles.
Without the Higgs field, Thomson explains, “all known particles would be massless,” fundamentally altering the structure of atoms and, consequently, the universe as we know it. However, the Higgs boson’s role extends beyond simply providing mass; researchers are now intensely focused on understanding its deeper nature, questioning whether it is a fundamental, singular particle or merely one of several Higgs bosons. The LHC’s upcoming high-luminosity upgrade is designed to produce a large number of Higgs bosons, enabling scientists to measure key properties, such as its self-interaction, for the first time. Despite the success of the standard model and the Higgs boson discovery, significant questions remain unanswered. The model fails to account for dark matter, the invisible substance comprising the majority of the cosmos, and offers no explanation for the observed matter-antimatter asymmetry in the universe. “We know there’s dark matter out there,” Thomson states, “At some point, we will discover what it is.” The pattern of particle masses is prompting investigation into whether a hidden fundamental principle governs these values, potentially linked to the Higgs boson. The pursuit of answers has led to proposals for even more powerful colliders, such as the Future Circular Collider (FCC), which could produce a large number of these particles in a controlled environment to probe their properties and search for deviations from expected behavior. Occasionally, Thomson admits, he compiles a list of the ten biggest questions in particle physics, and half of them “have something to do with the Higgs boson,” underscoring its central role in the ongoing quest to understand the universe’s deepest secrets.
W and Z Boson Confirmation and Neutrino Mass Evolution
Confirmation of the W and Z bosons, fundamental force carriers of the weak interaction, stands as a cornerstone of the Standard Model’s success, a triumph achieved at CERN. These particles, initially theorized to mediate radioactive decay, were experimentally verified decades after their prediction, solidifying the electroweak theory uniting electromagnetism and the weak force. The detection wasn’t merely about finding particles; it validated a profound conceptual shift in understanding how forces operate at the subatomic level, a revelation that fundamentally altered the landscape of particle physics. Mark Thomson notes that when he first read about CERN as a teenager, the existence of these bosons was still unknown, highlighting the dramatic progress made in the field over the past forty years. Beyond the W and Z bosons, the revelation that neutrinos possess mass represents another significant departure from the original Standard Model.
For over twenty-five years, the prevailing assumption was that these elusive particles were massless, behaving as predicted by the simplest theoretical frameworks. However, experiments observing neutrino oscillations, the spontaneous change of one neutrino “flavor” into another, demonstrated definitively that neutrinos do have mass, albeit incredibly small. “Just over 25 years ago, we thought these particles were massless,” Thomson explains, emphasizing the unexpected nature of this discovery. This finding necessitated an extension of the Standard Model to accommodate massive neutrinos, opening new avenues of research into their properties and potential role in cosmological phenomena. The implications of neutrino mass extend beyond simply modifying the Standard Model; it hints at physics beyond our current understanding. The observed masses, while tiny, are not easily explained by the simplest extensions of the Standard Model, suggesting the existence of new particles or interactions. The pattern of particle masses remains a perplexing puzzle. “We know there’s dark matter out there.”
We’ve definitely not found everything. If you take a look back at the really big, game-changing discoveries – like neutrino mass, the Higgs boson, the discovery of gravitational waves, the discovery of dark energy – these things come along every five to 10 years.
LHC Upgrades for High-Luminosity & Increased Collisions
Mark Thomson, newly appointed director general of CERN, oversees a pivotal moment for the laboratory as the Large Hadron Collider prepares for a four-year shutdown commencing on June 29th at 6am. This isn’t merely a pause in operations; it’s a comprehensive upgrade designed to dramatically increase the LHC’s luminosity, effectively boosting the rate of particle collisions and sharpening the search for elusive phenomena beyond the Standard Model. The core of this enhancement involves replacing 1.2 kilometers of the 27-kilometer ring over four years with advanced technology focused on intensifying the magnetic fields that steer particles. By concentrating collisions into a smaller space, physicists aim to unlock answers to some of the most pressing questions in modern physics. The upgrade’s technical complexity is considerable, with the installation of new superconducting cables representing the largest undertaking at CERN in the last two decades.
Simultaneously, the ATLAS and Compact Muon Solenoid experiments are undertaking significant detector upgrades, further amplifying the LHC’s capabilities. The increased data volume will allow physicists to probe the Higgs boson’s properties with unprecedented detail, potentially revealing connections to dark matter and other unresolved mysteries. Looking beyond the high-luminosity phase, CERN is already considering the construction of an even more powerful collider, the Future Circular Collider (FCC). This ambitious project, estimated to cost £13 billion, is driven by the desire to address questions that remain unanswered even with the upgraded LHC. The FCC, initially envisioned as an electron-positron collider, could potentially reach energy scales beyond those achievable with the LHC. This long-term vision, supported by a strong consensus across the European scientific community, aims to push the boundaries of our understanding of the universe and explore physics at energy scales that were previously inaccessible, potentially revealing new particles and forces that govern reality.
I’m quite optimistic that at some stage in the next 10-plus years, we are going to break the standard model that we have. We are going to find a chink in its armour.
Unresolved Questions: Dark Matter and Matter-Antimatter Asymmetry
The pursuit of fundamental particles and forces at CERN isn’t merely an academic exercise; the implications of understanding the universe’s building blocks ripple into technological advancements and our very comprehension of existence. A prime example is the proposed Future Circular Collider (FCC), estimated to require a £13 billion investment, reflecting CERN’s commitment to addressing these unresolved questions. These aren’t simply theoretical puzzles; they concern the composition of most of the universe and the very reason we exist. The FCC, designed as a potential machine to produce vast numbers of these particles, aims to probe interactions between the Higgs boson and dark matter, potentially revealing clues to its composition. “I would really love to know why particles’ masses have that pattern,” Thomson confessed, highlighting a key area of investigation. Beyond dark matter, the asymmetry between matter and antimatter presents another fundamental challenge.
The Big Bang should have produced equal amounts of both, leading to mutual annihilation and a universe filled only with energy. The fact that matter predominates is a profound puzzle. “We also don’t know why there’s any matter left in the universe after the big bang,” Thomson explained, outlining the core of the problem. The LHC’s upcoming high-luminosity upgrade, involving the replacement of 1.2 kilometers of its 27-kilometer ring with advanced technology over four years, is designed to increase collision rates and potentially reveal subtle differences in the behavior of matter and antimatter. However, truly unraveling this asymmetry may require the FCC, capable of probing the electroweak scale, the energy level present approximately 100th of a nanosecond after the Big Bang, where the fundamental forces began to differentiate.
Occasionally, I write down my 10 big questions in particle physics, and half of them have something to do with the Higgs boson. Like, does the Higgs boson interact with dark matter?
Future Circular Collider: A Proposed Higgs Boson “Factory”
The pursuit of understanding the universe often feels like chasing a receding horizon; even as we achieve monumental breakthroughs, deeper mysteries emerge, demanding ever more ambitious tools and experiments. While the Large Hadron Collider continues to yield insights, the scientific community is already looking ahead, contemplating a successor capable of unlocking the next layer of reality: the Future Circular Collider, or FCC. This proposed £13 billion undertaking isn’t simply about building a larger machine, but about fundamentally shifting how we investigate the Higgs boson and the forces governing the cosmos. The impetus for the FCC stems from the limitations of the Standard Model, despite its remarkable success.
These aren’t merely academic curiosities; they concern the very fabric of existence, such as the nature of dark matter and the imbalance between matter and antimatter in the universe. “If we see deviations from the properties we expect, we might then learn something about the unknown universe,” Thomson suggests, highlighting the potential for discovering physics beyond the Standard Model. The design of the FCC is particularly innovative. It would initially function as an electron-positron collider, providing a cleaner signal for Higgs boson production, before potentially evolving into a hadron collider similar to the LHC, but with significantly increased energy. This staged approach offers flexibility and maximizes the scientific return on investment. The proposed collider would span 80 to 100 kilometers, dwarfing the LHC’s 27-kilometer ring, and would be built using advanced superconducting magnet technology. This isn’t just about scale, however; it’s about precision.
The ability to measure the Higgs boson’s properties with greater accuracy could reveal subtle clues about its role in the universe and its connection to phenomena like dark matter. “We know [dark matter] is there, but we don’t know the answer to that question,” Thomson acknowledges, emphasizing the urgency of this research. The FCC isn’t conceived as a final destination, but as a stepping stone, and the consensus among European scientific communities regarding the FCC’s importance is unusually strong, signaling a collective commitment to addressing the fundamental questions that continue to challenge our understanding of the universe.
