CERN's Final Countdown: The Last Months of Run 3, a $17 Billion Decision, and the Future of Particle Physics

The world's most powerful particle accelerator is racing toward two finish lines simultaneously. At the Large Hadron Collider beneath the Swiss-French border, physicists are squeezing every last collision from Run 3 before the machine shuts down on June 29, 2026, for a 47-month upgrade that will transform it into something even more extraordinary. Meanwhile, 100 kilometers away in Geneva, CERN member states are preparing for the most consequential vote in the organization's 72-year history.

In May 2026, the CERN Council will gather in Budapest to decide whether to approve the Future Circular Collider — a 91-kilometer underground ring that would dwarf the current 27-kilometer LHC and cost approximately $17 billion. If approved, construction would begin in 2030, with first collisions targeted for 2047. The machine would run for at least 15 years, potentially extending operations into the 2060s when combined with a second-phase 100 TeV hadron collider.

This isn't just about building a bigger toy for physicists. The decision will determine whether fundamental physics continues its century-long march toward understanding the universe's deepest laws, or whether humanity steps back from the frontier of knowledge. The stakes are immense, the costs are staggering, and the timeline stretches across three generations of scientists.

But before we look decades into the future, let's examine what's happening right now at CERN — because the final months of Run 3 are delivering some of the most precise measurements and surprising discoveries in the LHC's 14-year operational history.

Run 3 by the Numbers: A Record-Breaking Performance

When the LHC restarted in July 2022 after a three-year shutdown, it came back stronger. The collision energy increased from 13 TeV to 13.6 TeV — the highest energy ever achieved in a laboratory. The luminosity (a measure of collision rate) was pushed higher than ever before. And the four main experiments — ATLAS, CMS, LHCb, and ALICE — were equipped with upgraded detectors and faster electronics.

Three and a half years later, Run 3 has exceeded even optimistic projections. By the time the LHC shuts down on June 29, 2026, it will have delivered approximately 500 inverse femtobarns of integrated luminosity to both the ATLAS and CMS experiments. To translate that into more tangible terms: that's roughly 50 million billion proton-proton collisions recorded and analyzed.

The year 2025 was particularly remarkable. The LHC delivered 125 inverse femtobarns in a single year — the highest annual luminosity in its history. This broke the previous record set in 2018, and it represents one-quarter of Run 3's total output compressed into just 12 months of operation.

The LHCb experiment, designed to study the subtle differences between matter and antimatter, also had a banner year. It recorded 11.8 inverse femtobarns in 2025 — shattering its previous annual record. This was made possible by a revolutionary software trigger system installed during Long Shutdown 2 that allows LHCb to process collision data at unprecedented rates.

What makes these numbers even more impressive is the machine availability. The LHC operated with over 90% efficiency throughout Run 3, meaning that when it was scheduled to run, it actually ran. This is the result of decades of operational experience, meticulous maintenance, and a team of engineers who can diagnose and fix problems with a machine that operates at temperatures colder than outer space and magnetic fields 200,000 times stronger than Earth's.

But raw collision counts only matter if you can extract physics from them. And that's where Run 3 has truly shined.

The Discovery Sprint: Precision, Anomalies, and Antimatter

The Higgs boson — discovered at the LHC in 2012 — remains the star of the show. This quantum of the Higgs field gives mass to fundamental particles, and understanding its properties is crucial to testing the Standard Model of particle physics. Run 3 has delivered the most precise measurements of the Higgs boson's mass ever achieved.

In late 2024, the ATLAS collaboration announced a new measurement: 125.11 GeV with an uncertainty of just ±0.11 GeV. That's a precision of 0.09% — the most accurate measurement of the Higgs mass to date. The CMS collaboration independently measured 125.35 GeV with an uncertainty of ±0.15 GeV, achieving similar precision.

Why does this matter? Because the Higgs mass isn't arbitrary — it's connected to the stability of the universe itself. Some theoretical models suggest that if the Higgs mass were slightly different, the vacuum of space could be metastable, meaning the universe could eventually decay into a lower-energy state (which would be, to put it mildly, bad for us). Precise measurements help physicists test these theories and understand whether we live in a stable or merely long-lived universe.

The Muon Channel: A Rare Glimpse

One of the most exciting results from Run 3 is evidence for the Higgs boson decaying into two muons — a process so rare that it occurs in only about 0.02% of Higgs decays. Muons are heavier cousins of electrons, and the Higgs should couple to them proportionally to their mass. But actually seeing this decay requires enormous statistics and sophisticated analysis techniques.

In 2024, the ATLAS collaboration reported 3.4 sigma evidence for the H→μμ decay mode, using the full Run 2 and partial Run 3 dataset. This doesn't quite reach the 5-sigma threshold required to claim discovery, but it's tantalizingly close. The observed significance was actually higher than the 2.5 sigma expected from Standard Model predictions, hinting that the data might be slightly exceeding expectations.

By the end of Run 3, physicists expect to have enough data to either confirm this decay mode at the discovery level or identify a discrepancy that could point toward new physics. Either outcome would be significant.

Antimatter's Heaviest Mystery

While the Higgs grabs headlines, other experiments at the LHC are pushing into equally exotic territory. The ALICE experiment, designed to study the quark-gluon plasma created in heavy-ion collisions, announced in 2024 the first evidence for antihyperhelium-4 — the heaviest antimatter hypernucleus ever observed.

Let's unpack that mouthful. A hypernucleus is an atomic nucleus that contains not just protons and neutrons, but also strange quarks in the form of hyperons (particles like the lambda baryon). Antihyperhelium-4 is the antimatter version of this already exotic state: it contains two antiprotons, one antineutron, and one antilambda (which itself contains an antistrange quark).

ALICE observed this state with 3.5 sigma significance by sifting through billions of lead-lead collisions. The discovery is important for understanding how antimatter behaves in extreme conditions, and it provides stringent tests of CPT symmetry — the fundamental principle that physics should look the same if you swap matter with antimatter, reverse spatial coordinates, and reverse time.

The Exotic Zoo Expands

The LHC isn't just confirming Standard Model predictions — it's discovering new particles that the Standard Model predicted should exist but had never been observed. These are exotic hadrons: bound states of quarks and gluons that go beyond the familiar proton and neutron.

Since 2012, the LHC has discovered approximately 80 exotic particles, including tetraquarks (four-quark states) and pentaquarks (five-quark states). In Run 3, the focus has shifted from discovery to precision measurement. The X(6600), X(6900), and X(7100) resonances — all-charm tetraquarks discovered in Run 2 — have had their properties measured with unprecedented accuracy.

These measurements help physicists understand how quarks bind together under the strong nuclear force. The exotic states are predicted by quantum chromodynamics (QCD), the theory of the strong force, but calculating their properties from first principles is extraordinarily difficult. Experimental data provides crucial tests of theoretical models.

The Deuteron Puzzle Solved

One of the more surprising results from Run 3 solved a long-standing mystery about how deuterons — nuclei consisting of one proton and one neutron — form in high-energy collisions. The question was whether they form during the initial chaotic fireball of quarks and gluons, or later when the system has cooled and expanded.

Using sophisticated statistical techniques applied to Run 3 data, physicists determined that deuterons form during the hadronic phase — after the quark-gluon plasma has cooled into ordinary hadrons. This might seem like a technical detail, but it's crucial for understanding the evolution of the early universe and the conditions inside neutron stars.

In recognition of the LHC's contributions to fundamental physics, all four major experiments — ATLAS, CMS, LHCb, and ALICE — were jointly awarded the 2025 Breakthrough Prize in Fundamental Physics. The $3 million prize was shared among the thousands of physicists who designed, built, operated, and analyzed data from these instruments.

Bowling Pins and Plasma: Lighter Ions at the LHC

While the LHC is famous for smashing protons together at nearly the speed of light, it also collides heavy nuclei to recreate conditions from the first microseconds after the Big Bang. Typically, these heavy-ion runs use lead nuclei, which contain 208 nucleons (protons and neutrons). But in June and July 2025, the LHC did something unprecedented: it collided oxygen nuclei and neon nuclei — and even ran asymmetric proton-oxygen collisions.

This wasn't just for variety. Physicists wanted to test whether lighter nuclei could produce the quark-gluon plasma (QGP) — the exotic state of matter where quarks and gluons roam freely instead of being confined inside protons and neutrons. In the early universe, everything was QGP for about the first 10 microseconds. Today, we can recreate it only in the most violent collisions.

The big question was: can you make QGP with smaller colliding systems, or do you need the full mass of lead nuclei? The 2025 oxygen-oxygen and neon-neon runs provided a definitive answer. The ALICE collaboration reported significant evidence of QGP formation even in these lighter-ion collisions, based on signatures like collective flow (particles moving together as if in a liquid) and strangeness enhancement (more strange quarks produced than expected from independent collisions).

Perhaps most intriguingly, the neon-neon collisions confirmed that neon nuclei are prolate — shaped like bowling pins rather than spheres. This had been predicted by nuclear theory, but the LHC data provided direct experimental confirmation. When prolate nuclei collide tip-to-tip versus side-to-side, they produce different collision geometries and different experimental signatures.

These results extend our understanding of QGP into a new regime. They suggest that the phase transition from ordinary hadronic matter to QGP might occur even in relatively small colliding systems, which has implications for neutron star mergers and the early universe's evolution.

Flavor Anomalies: The Hint of a Fifth Force

While the Higgs boson and exotic hadrons grab headlines, some of the most tantalizing hints of physics beyond the Standard Model come from a less glamorous source: B mesons — particles containing a bottom quark. The LHCb experiment specializes in studying these particles, and over the past decade, it has accumulated a series of puzzling measurements that don't quite match Standard Model predictions.

The most prominent of these flavor anomalies involves the ratios R(D) and R(D*) — measurements of how often B mesons decay to tau leptons versus muons. According to the Standard Model, the only difference between these decays should be the masses of the leptons involved. But LHCb measurements consistently show an excess of tau decays compared to predictions.

The latest Run 3 analysis, incorporating the record-breaking 2025 dataset, shows a 2.1 sigma deviation from the Standard Model for R(D*). This isn't statistically significant enough to claim a discovery (which requires 5 sigma), but it's persistent across multiple measurements and multiple experiments (Belle and Belle II have seen similar effects).

Why does this matter? If confirmed, it would provide evidence for lepton universality violation — the principle that electrons, muons, and taus should behave identically except for their masses. Violations of lepton universality could point toward new force-carrying particles, often called leptoquarks or Z-prime bosons, that couple differently to different lepton generations.

This would be revolutionary. The Standard Model has three fundamental forces: electromagnetism, the weak force, and the strong force. (Gravity isn't included because we don't have a quantum theory of it yet.) Evidence for a fifth force that mediates interactions between quarks and leptons would shatter the Standard Model and point toward a more complete theory.

But 2.1 sigma isn't 5 sigma. It could be a statistical fluctuation, or it could be a systematic uncertainty in the theoretical predictions, or it could be real new physics. The only way to know for sure is to collect more data — which is exactly what the High-Luminosity LHC will do.

The LHCb upgrade installed during Long Shutdown 2 has transformed the experiment's capabilities. The new software trigger allows LHCb to process data at 40 MHz — the full LHC collision rate — instead of being limited by hardware triggers. This is why the 2025 dataset alone exceeded the combined Run 1 and Run 2 datasets.

Looking ahead, one of LHCb's priority targets for 2026 is searching for the Tbb tetraquark — an exotic particle containing two top quarks and two bottom antiquarks. If it exists, it would be the first exotic hadron that's stable against strong decay (it could only decay via weak interactions). Finding it would be a major discovery and would provide a new testing ground for understanding quark binding.

Long Shutdown 3: The Great Upgrade

On June 29, 2026, at approximately 6:00 AM local time, the LHC will circulate its last beams of Run 3. Engineers will extract the beams, safely dumping them into massive graphite absorbers. And then, for the first time in nearly four years, the LHC will fall silent.

What follows is Long Shutdown 3 — a 47-month marathon of upgrades, maintenance, and transformation that will turn the LHC into the High-Luminosity LHC (HL-LHC). When it restarts in June 2030, it will be capable of delivering collision rates 5 to 7 times higher than the current machine.

The scale of LS3 is staggering. Approximately 100 new magnets of 11 different types will be installed around the two main interaction points where ATLAS and CMS detect collisions. These include:

• Inner triplet magnets: These focus the beams down to incredibly tiny spots at the collision point. The new magnets use niobium-tin (Nb₃Sn) superconductors instead of the traditional niobium-titanium. This allows them to achieve magnetic fields up to 12 Tesla — about 40% stronger than the current magnets.

• Crab cavities: Sixteen of these devices, made from ultra-pure niobium and cooled to 2 Kelvin (even colder than the 1.9 K magnets), will tilt the proton bunches just before collision. This compensates for the fact that bunches cross at an angle, increasing the effective collision rate. In 2024, CERN successfully demonstrated crab cavities operating at up to 5 megavolts — the highest voltage ever achieved in such devices.

To install this equipment, engineers will drill 28 vertical cores linking new surface galleries to the LHC tunnel 100 meters below ground. Some of the new magnets weigh over 30 tons and must be lowered through these narrow shafts with millimeter precision. The logistics are comparable to a major construction project, except everything must be done without contaminating the ultra-high-vacuum environment of the accelerator.

The ATLAS and CMS detectors will also undergo major upgrades. ATLAS is installing a completely new inner tracker with higher granularity to cope with the increased collision rate. CMS is upgrading its calorimeters and muon systems. Both experiments are replacing front-end electronics and trigger systems to handle the tsunami of data that HL-LHC will produce.

Everything is proceeding on schedule. The first Nb₃Sn magnets have already been manufactured and tested. The crab cavity systems have been validated. The detector components are in production. Barring unforeseen problems, LS3 should complete on time, bringing the HL-LHC online in mid-2030.

The High-Luminosity LHC: Turning Up the Intensity

When Run 4 begins in 2030, physicists will immediately notice the difference. The peak luminosity — the instantaneous collision rate — will jump from about 2.0×10³⁴ cm⁻²s⁻¹ to somewhere between 5.0 and 7.5×10³⁴ cm⁻²s⁻¹. To translate that into more physical terms: instead of about 60 simultaneous collisions every time two proton bunches cross, there will be 140 collisions.

This is both a blessing and a curse. More collisions mean more data, which translates to better statistical precision and increased sensitivity to rare processes. But it also means more pileup — the challenge of disentangling which particles came from which collision. The detector and software upgrades are specifically designed to handle this environment.

Over the full HL-LHC program, ATLAS and CMS each aim to collect 3,000 inverse femtobarns of data — often written as 3 ab⁻¹ (three inverse attobarns) to avoid large exponents. This is 10 times the original design luminosity of the LHC, and about 6 times the total that Run 1, Run 2, and Run 3 will have delivered combined.

The HL-LHC will produce approximately 200 petabytes of data per year — about 200 million gigabytes. For perspective, that's equivalent to streaming Netflix in 4K for about 60,000 years. All of this data must be recorded, stored, distributed to computing centers worldwide, and analyzed by thousands of physicists.

The operational plan calls for:

• Run 4: 2030-2033 (about 1,000 fb⁻¹)
• Long Shutdown 4: 2034-2035 (brief maintenance shutdown)
• Run 5: 2036-2041 (about 2,000 fb⁻¹, reaching 3,000 fb⁻¹ total)

If everything goes according to plan, by the end of Run 5 in 2041, ATLAS and CMS will each have recorded approximately 180 million Higgs boson events, compared to about 10 million by the end of Run 3. This will enable precision measurements of Higgs properties at the percent level or better, searching for tiny deviations that could reveal new physics.

But even as the HL-LHC is being built, physicists are looking beyond it to an even more ambitious project — one that would make the LHC look small by comparison.

The $17 Billion Question: FCC-ee

Imagine a circular tunnel 91 kilometers in circumference — more than three times the length of the LHC — buried between 180 and 400 meters underground in the bedrock beneath Lake Geneva and the surrounding countryside. Inside it, electrons and positrons (antielectrons) would circulate in opposite directions at 99.999999996% the speed of light before colliding at four interaction points.

This is the Future Circular Collider electron-positron machine, or FCC-ee for short. It would be the world's most powerful lepton collider — a machine designed to produce known particles (Z bosons, W bosons, Higgs bosons, top quarks) in enormous quantities with exquisite precision, rather than searching for new heavy particles at the highest energies.

The physics case is compelling:

• 6 trillion Z bosons (compared to about 30 million produced at LEP, CERN's previous electron-positron collider)
• 240 million W boson pairs (about 100 times LEP's production)
• 3 million Higgs bosons (clean events without the messy proton-proton collision background)
• 2 million top-quark pairs (allowing precision top quark physics in a clean environment)

The FCC-ee would operate at four different energy levels optimized for different physics:

1. Z pole (91 GeV): Five years producing Z bosons
2. W threshold (161 GeV): Two years producing W pairs
3. Higgs pole (240 GeV): Three years producing Higgs bosons
4. Top threshold (365 GeV): Five years producing top quarks

Each energy requires different accelerator configurations, but because FCC-ee is a circular machine, it can run at all four points over its operational lifetime.

The precision would be extraordinary. The Higgs mass could be measured to about 1 megaelectronvolt (0.001% precision), compared to the current 110 MeV uncertainty. The Higgs couplings to other particles could be measured to percent-level precision, testing whether the Higgs truly gives mass to all particles as the Standard Model predicts, or whether there are subtle deviations pointing to new physics.

But this precision comes at a price: approximately CHF 15.3 billion (roughly $17-18 billion US at current exchange rates). About one-third of that cost is for civil engineering — excavating the 91-kilometer tunnel, building the four underground experimental caverns, and constructing the surface facilities.

Here's where the story takes an interesting turn. In late 2024 and early 2025, a group of private donors committed €860 million (about $1 billion) toward FCC construction. The contributors include:

• Yuri Milner, the Russian-Israeli-British billionaire who founded the Breakthrough Prize
• Eric Schmidt, former Google CEO
• John Elkann, representing the Agnelli family (owners of Ferrari, Juventus, and major Stellantis shareholders)
• Xavier Niel, French telecommunications billionaire

This represents about 5-6% of the total FCC-ee budget. While not decisive by itself, it's a significant show of private sector confidence in the project's value. It also addresses one of the common criticisms: "Why should taxpayers fund this when billionaires could pay for it?" Well, some billionaires are paying for part of it.

The rest would come from CERN's member states (23 countries, mostly European) plus potential contributions from observer states (USA, Japan, Russia, India, and others). The cost would be spread over roughly 18 years of construction, making the annual contribution manageable for most participating nations.

The timeline is aggressive but realistic:

• May 2026: Budapest Council meeting — go/no-go decision
• 2026-2030: Final design and approval process
• 2030: Construction begins (civil engineering starts first)
• 2030s: Tunnel excavation and accelerator construction in parallel
• 2047: First collisions
• 2047-2062: 15 years of operations at four energy levels
• 2060s: Potential FCC-hh (hadron) upgrade using the same tunnel

If approved on schedule in May 2026, the first physics results from FCC-ee would arrive in the late 2040s — more than 20 years from now. The scientists who will analyze that data are currently in elementary school. The engineers who will build the detectors are in high school or starting university. This is not a project for immediate gratification.

FCC-ee vs the Alternatives: What Else Is On the Table?

The FCC is not the only next-generation collider under consideration. Let's examine the alternatives and how they compare.

CLIC: The Linear Option

The Compact Linear Collider (CLIC) was CERN's other major proposal for a next-generation machine. Instead of a circular tunnel, CLIC would be a linear accelerator about 11-50 kilometers long (depending on energy stage), accelerating electrons and positrons on a collision course using novel two-beam acceleration technology.

CLIC has some advantages: it could potentially reach higher energies than FCC-ee (up to 3 TeV), and it wouldn't face the synchrotron radiation losses that plague circular electron machines. But it has critical disadvantages: the same collision point can't be used repeatedly (the beams only pass through once), and the luminosity is lower.

In 2020, the European Strategy for Particle Physics concluded that CLIC offers "substantially reduced precision physics" compared to circular electron-positron colliders. While the technology development continues, CLIC is no longer considered the leading candidate for Europe's next major facility.

The Muon Collider: High Risk, High Reward

Perhaps the most exotic proposal is a muon collider — a circular machine that would collide muons (heavy cousins of electrons) at energies of 10 TeV or more. Muons have 200 times the mass of electrons, which means they radiate far less synchrotron radiation in circular motion. This allows a relatively compact ring to reach very high energies.

The challenges are severe:

• Muon lifetime: Muons decay in 2.2 microseconds. You have to produce them, accelerate them to high energy, and collide them before they disappear.
• Neutrino radiation: Decaying muons produce neutrino beams that punch through the Earth and emerge on the other side of the planet. The dose to the public must be carefully managed.
• Cooling: The muons must be "cooled" (their momenta made more uniform) very quickly, which requires technology that doesn't yet exist at the required scale.
• Magnetic fields: The collider ring would need solenoid magnets producing 10-15 Tesla fields, significantly stronger than standard dipole magnets.

Muon collider R&D is proceeding at Fermilab, CERN, and other labs, but most experts estimate it will be at least 2040 before the technology is mature enough to commit to construction. It's an option for the generation after FCC, not a competitor for the current decision.

FCC-hh: The Ultimate Hadron Machine

The long-term vision for the FCC includes a second phase: FCC-hh, a hadron collider that would use the same 91-kilometer tunnel to collide protons at 100 TeV center-of-mass energy — more than seven times the LHC's 14 TeV.

FCC-hh would be a direct energy frontier machine, capable of discovering new particles up to about 30-50 TeV in mass. It would produce more than 20 billion Higgs bosons over its lifetime (compared to about 3 million at FCC-ee). It would explore the terascale region where many beyond-Standard-Model theories predict new physics.

The FCC-hh would not operate simultaneously with FCC-ee — it would use the same tunnel after FCC-ee operations conclude, likely starting in the 2070s. This staged approach allows the massive civil engineering investment to serve two different physics programs over many decades.

But FCC-hh comes with its own price tag — likely another $15-20 billion for the hadron collider hardware — and its own challenges. The dipole magnets would need to produce fields of about 16 Tesla (compared to the LHC's 8.3 Tesla and HL-LHC's 12 Tesla). This pushes the limits of superconducting magnet technology and might require high-temperature superconductors like those being developed for fusion reactors.

China's proposed CEPC (Circular Electron Positron Collider) followed by SPPC (Super Proton-Proton Collider) follows a similar staged strategy: build a 100-kilometer circular tunnel, start with electron-positron physics, then upgrade to hadron collisions decades later.

Computing at Exascale: Managing the Data Deluge

All the precision measurements and rare discoveries in the world mean nothing if you can't process the data. And modern particle physics produces data at scales that would terrify most tech companies.

The Worldwide LHC Computing Grid (WLCG) is a distributed computing infrastructure spanning over 160 data centers in more than 40 countries. It processes more than 2 million tasks per day, provides hundreds of petabytes of storage, and supports about 10,000 physicists analyzing data simultaneously.

CERN itself provides about 20% of the total computing resources, with the rest distributed among Tier-1 centers (national facilities that provide large-scale storage and processing) and Tier-2 centers (regional facilities that support specific analysis tasks). In December 2025, Serbia joined as a full Tier-1 member, contributing 24,000 CPU cores and 18 petabytes of storage.

The HL-LHC will push this system to its limits. With 200 petabytes of data per year, the storage requirements alone will exceed the capacity that can be achieved with constant budget growth. This is driving innovation in several areas:

Software Efficiency

Much of the data reduction happens in software triggers — algorithms that decide in microseconds which collisions to keep and which to discard. Modern machine learning techniques are being integrated into these triggers to improve efficiency. A neural network can evaluate complex patterns faster than traditional algorithms, allowing more interesting events to be saved for analysis.

Open Source Collaboration

In 2024, CERN established the Open Source Program Office (OSPO) to formalize its commitment to open-source software development. Much of the software used for LHC data analysis — ROOT (data analysis framework), Geant4 (detector simulation), and various reconstruction algorithms — is open-source and freely available.

This benefits both CERN and the wider community. CERN gets contributions from developers outside particle physics who improve performance and find bugs. The community gets access to industrial-strength tools for data analysis that have been battle-tested on the world's largest scientific datasets.

Strategic Partnerships

In late 2025, CERN announced a collaboration with ZenDis, a German government initiative for digital sovereignty and open-source infrastructure. The partnership will develop open-source solutions for large-scale data management that can be used both for particle physics and for other European scientific and industrial applications.

The distributed computing model has proven remarkably resilient. During the COVID-19 pandemic, when many physicists couldn't access their offices, the WLCG kept running, and analysis work continued largely uninterrupted. This is a testament to the robustness of a system designed to survive partial outages and adapt to changing resource availability.

Looking ahead to the FCC era, the computing challenges will be even greater. FCC-ee will produce cleaner events than the LHC (less background, simpler reconstruction), but the sheer number of Z bosons and other particles will generate enormous datasets. Planning for computing infrastructure will need to begin a decade before first collisions, ensuring that storage, networking, and processing capacity scale appropriately.

What This Means: The Next 80 Years

We stand at a crossroads. The decisions made in the next few months — in Geneva, in Budapest, in the capitals of CERN's member states — will shape the trajectory of particle physics for the rest of the 21st century.

If the FCC receives approval in May 2026, Europe will commit to maintaining its leadership in experimental particle physics through at least the 2070s. The staged program — FCC-ee in the 2040s and 2050s, followed by FCC-hh in the 2070s and beyond — would provide European physicists with the world's most powerful tools for exploring fundamental physics across three generations of researchers.

If the FCC is rejected, or delayed indefinitely, the future becomes murkier. China's CEPC proposal could move forward, potentially making Beijing the center of particle physics by mid-century. The US could revive linear collider plans or invest heavily in muon collider R&D. Or the entire field could pivot away from accelerator-based physics toward alternatives like neutrino experiments, dark matter searches, and precision measurements using atomic physics.

But particle physics is not just about building bigger machines. The HL-LHC will run for a decade, producing precision measurements that test the Standard Model to unprecedented accuracy. LHCb will accumulate flavor physics data that could reveal lepton universality violation or other subtle anomalies. ALICE will map the phase diagram of QCD matter, understanding how quarks and gluons behave under conditions that haven't existed since the early universe.

And the theoretical community will continue to wrestle with the deep questions that experiments can't yet answer: Why is there more matter than antimatter in the universe? What is dark matter made of? Why is the Higgs mass 125 GeV and not some other value? Why are there three generations of matter particles? Is spacetime fundamentally smooth or does it have a grainy structure at the Planck scale?

Some of these questions might be answered by the HL-LHC or the FCC. Others might require experiments we haven't even conceived yet — gravitational wave detectors sensitive to the stochastic background from cosmic phase transitions, neutrino telescopes embedded in ice or ocean, or space-based detectors searching for antimatter galaxies.

What's clear is that fundamental physics remains vibrantly alive. The field has not "ended" with the discovery of the Higgs boson, any more than it ended with the discovery of the W and Z bosons in 1983, or the top quark in 1995, or the tau neutrino in 2000. Each discovery opens new questions. Each precision measurement either confirms the Standard Model to another decimal place — itself a profound result — or reveals a discrepancy that points toward new physics.

The final months of Run 3 are a celebration of what's already been achieved: 500 inverse femtobarns of data, unprecedented precision on the Higgs mass, evidence for incredibly rare Higgs decays, discovery of antimatter hypernuclei, hints of flavor anomalies that could signal a fifth force. These are remarkable accomplishments produced by thousands of physicists, engineers, and technicians working together over decades.

But they're also a prelude. The HL-LHC will deliver 6 times more data. The FCC-ee could deliver precision that makes today's measurements look crude by comparison. And somewhere in those future collisions, hidden in the debris of trillions of particle interactions, might lie the clues that unlock the next revolution in our understanding of nature.

That's what's at stake in Budapest this May. Not just a $17 billion construction project, but humanity's commitment to understanding the universe at its most fundamental level. The next 80 years of particle physics hang in the balance.

The countdown has begun.