How “big tent” particle physics is reshaping physics research

On the morning of July 4, 2012, Fabiola Gianotti and Joe Incandela stood before a packed auditorium at CERN to announce the discovery of the Higgs boson. Scientists across the globe had tuned in. In the United States, researchers woke in the middle of the night to watch.

One of us, Maria, a member of the CMS experiment, was in the auditorium. The other, Michael, was in Colorado at the Aspen Center for Physics with a room full of theorists, who stayed up into the wee hours of the morning to hear the electrifying news.

The discovery, which completed the Standard Model, was a triumph of particle physics and science. But who, exactly, had done the discovering?

Of course, there was no single person: 3,172 authors were listed on the ATLAS collaboration's discovery paper alone, which allotted 24 pages just to names. As a result, the discovery of the Higgs boson was hailed as an example of the successes of collaborative “big science.”

But the discovery not only showcased big science. It was a harbinger for a new style in particle physics. It required particle physicists, yes, but also engineers, accelerator scientists, computational scientists, and low-temperature physicists. In other words, the Higgs discovery showcased the “big tent” of people and ideas needed to understand the fundamental nature of matter, energy, space, and time.

This big tent reveals how profoundly particle physics has changed, and how the field is reshaping the very nature of physics research.

The explosion of particle physics

Today, the particle physics tent is enormous. It attracts condensed matter, gravitational, and atomic, molecular, and optical (AMO) physicists, along with astronomers, computational scientists, accelerator physicists, and engineers. Other researchers in the field focus on quantum information science, artificial intelligence, and machine learning.

This explosion did not happen overnight. Twenty-five years ago, elementary particle physics was about particles and forces, done by experimentalists using accelerators and theorists making sense of it all.

Then the questions began changing. The Standard Model, with the Higgs boson at its center, beautifully explained the known forces and particles, but it couldn’t account for what cosmologists were seeing: dark matter holding galaxies together, dark energy accelerating the universe's expansion, and evidence of cosmic inflation. These concepts were instead central to another standard model, the LambdaCDM model of cosmology.

Suddenly, understanding matter and energy meant grappling with the structure of space, time, and the universe. Particle physics alone — at least, as it was then organized — couldn't answer these questions.

So the field expanded, and cosmologists and astrophysicists joined the tent. The Standard Model began mingling with the LambdaCDM model, uniting the big questions about matter and energy — the particles and their interactions — with big questions about space, time, gravity, and the origin of the universe. This unification also pulled in a host of theorists — string, gravity, and quantum information — who were themselves grappling with the nature and origin of space and time.

Meanwhile, AI, machine learning, and big data, tools used by many subfields, have dissolved traditional boundaries. Techniques pioneered in one area migrate to another. For example, analysis of large datasets in accelerator experiments and cosmic surveys use AI and machine learning, generating ideas that then cross back to computer science. And statistical techniques pioneered in astrophysics and cosmology are now routinely used in collider experiments.

As new questions arise, they require new approaches. Dark energy, the mysterious energy form that makes up 70% of the universe, can only be studied with telescopes that look deep into space and far back in time. Dark matter, which holds together galaxies and all cosmic structures, can also be studied by telescopes — but revealing its fundamental nature, and searching for the yet-undiscovered particles that comprise it, requires ultra-sensitive detectors in deep underground laboratories, shielded from cosmic rays. These experiments draw on techniques from optical and radio astronomy and condensed matter physics, as well as new quantum sensors developed by particle physicists.

Research on neutrinos also relies on diverse tools. We confirmed neutrinos’ existence with nuclear reactors. Accelerators revealed that the strange particles come in more than one type. And we used underground detectors to learn that neutrinos have mass and oscillate between types. (These discoveries led to four Nobel Prizes.)

There are still big neutrino mysteries: Are they their own antiparticles? What explains their tiny masses? Do their interactions violate matter/antimatter symmetry and explain the absence of antimatter in the universe today? Answering these questions requires the search for rare nuclear decays, neutrino beams from reactors and accelerators, and telescopes that probe the influence of cosmic neutrinos on the growth of structure in the universe.

Other mysteries, including the unification of the forces and particles, demand high-precision measurements. For example, the electric dipole moment of the electron offers a window into physics beyond the Standard Model. The search for fifth forces and deviations from Newtonian gravity at short distances may reveal clues about the unification of gravity with the other forces of nature. And all these efforts are pulling in new researchers, including condensed matter physicists, AMO physicists, and precision measurement scientists.

For researchers navigating particle physics today, especially those early in their careers, these big shifts in the field are impacting jobs, institutions, and scientists themselves.

Research opportunities

First, the expanding tent creates a broader array of global opportunities for researchers than existed a generation ago. Particle physicists today might work on an accelerator experiment at the Large Hadron Collider in Switzerland; study neutrinos at Fermilab in Illinois; map dark energy with powerful telescopes at Chile’s Rubin Observatory; hunt for dark matter at an underground laboratory in South Dakota or Italy; or measure the polarization of the cosmic microwave background at the South Pole.

There is enormous diversity not only in the experiments, but also in timescale and team size. Some projects, like cosmic surveys and collider research, have longer timescales and bigger teams. Smaller experiments and theory projects typically have smaller teams and timescales. This variety enables researchers to be involved in multiple activities at the same time or throughout their careers.

Consider Bruce Winstein, who shifted from studying subatomic particles with accelerators to studying the cosmic microwave background, bringing with him techniques and collaborators from particle physics. Or Barry Barish, who started his career at an accelerator, conducted research at an underground laboratory, and then headed the successful search for gravitational waves at LIGO, for which he shared the 2017 Nobel Prize.

Interdisciplinary scientists

Second, these new pathways are producing a different kind of scientist. A researcher who has worked on both a collider collaboration and a dark matter experiment, for example, emerges with unusual versatility: expertise in state-of-the-art instrumentation and tools, including machine learning and AI techniques; the ability to navigate both massive international teams and small, nimble groups; and the fluency to move between subdisciplines, making connections that researchers entrenched in a single domain might miss.

Beyond its benefits for science, this interdisciplinary style is good for scientists. Training organized by skills and techniques, rather than rigid field boundaries, tends to produce researchers who are highly adaptable, and highly employable. After all, many pressing scientific problems today — from climate change to quantum computing to AI — don't observe traditional disciplinary boundaries. Particle physicists trained in the big tent develop the creativity that is valued in both academia and industry, especially for emerging fields and technologies.

Evolving institutions

Third, the big tent model is reshaping institutions themselves. Physics departments are moving away from traditional subdiscipline silos — separate groups for, say, particle physics and condensed matter physics — and organizing instead around larger themes, like quantum measurement, nanoscience, or big data. Individual, faculty-led groups become specialized, but their interests and activities move across themes. Researchers interact and share ideas more often.

Theory offers a concrete example of this reshaping. Today at many institutions, theory is organized not by subdisciplines, but in cross-disciplinary centers where researchers use the same mathematical tools. The ten new theory institutes funded by the Leinweber Foundation follow a model like this. And one of us, Michael, benefitted early in his career from two pioneering theory centers, The Kavli Institute for Theoretical Physics at the University of California, Santa Barbara, and the Aspen Center for Physics. Both facilitated work across traditional silos — astrophysics, condensed matter physics, and particle physics — by bringing theorists together for workshops and meetings.

A humbling lesson for scientists

Particle physics is a humbling field. In exploring the mysteries of the universe, we confront our smallness within it, the strangeness of nature’s rules, and the limits of what we know. But for us, there is another humbling revelation: No single approach, no single set of tools, can answer the most fundamental questions. Understanding the origins of space and time, the nature of matter and energy, the destiny of the cosmos — these challenges demand more minds, perspectives, and creativity than any one discipline can provide.

For researchers, this means something concrete. This community needs expertise from across the physical sciences. If you’re drawn to big questions about the universe but haven't seen yourself in traditional particle physics, the tent is bigger now. And it needs you.

Note: The authors co-chaired the recent National Academies study “Elementary Particle Physics: The Higgs and Beyond,” which put forward a 40-year vision for the field of particle physics.