All the world is built out of 17 known elementary particles. Carlo Rubbia led the team that discovered two of them. In 1984, Rubbia shared the Nobel Prize in Physics with Simon van der Meer for their “decisive contributions” to the experiment that, the year before, had turned up the W and Z bosons. These particles convey one of the four fundamental forces, called the weak force, which causes radioactive decay.

Rubbia ran the experiment, called Underground Area 1 (or UA1), a bold and ambitious project at CERN laboratory near Geneva that sought traces of W and Z bosons in the chaos of high-energy particle collisions. Hundreds of billions of protons and antiprotons were accelerated close to the speed of light and then smashed together. At the time, antiprotons — which have a habit of rapidly destroying themselves when they come into contact with matter — had never been produced in abundance. Some of Rubbia’s peers favored alternative collider and detector designs, believing that antimatter was too volatile to be controlled in this way.

“We had zillions of different ideas. There was a lot of competition, but you cannot do two things at the same time,” Rubbia said. In the end, UA1 prevailed, and delivered.

More than three decades later, particle physics once again finds itself at a crossroads. A decision looms about which big particle-collider experiment to build next — if indeed one is built at all. While CERN’s Large Hadron Collider (LHC) has performed flawlessly, its collisions have yielded no signs of new particles beyond the expected 17, whose properties and interactions are described by the Standard Model of particle physics. This model makes incredibly accurate predictions about those particles’ behavior, yet it’s also understood to be an incomplete description of our world. It fails to include the gravitational force or dark matter — the mysterious substance that astronomers consider to be about five times more abundant than normal matter — or account for the universe’s matter-antimatter imbalance. Moreover, many theorists feel uneasy about the Standard Model’s inability to explain its own basic truths, such as why there are three families of quarks and leptons, and what determines the particles’ masses.

Rubbia, who at 85 remains at the forefront of the field, isn’t fazed by the absence of “new physics” in the LHC data. He urges his peers to press on in search of more and better data and to trust that answers will come. The Higgs boson — the 17th piece in the Standard Model puzzle — materialized at the LHC in 2012, and now Rubbia wants to explore its characteristics in depth with a state-of-the-art “Higgs factory.”

How best to do this is still up for debate, with competing designs ranging from a circular electron-positron collider 100 kilometers in circumference to a plasma wakefield accelerator, a tabletop experiment in which electrons “surf” on a wave of rapidly accelerating plasma. To Rubbia, the choice is clear: An innovative muon collider, he says, could produce thousands of Higgs bosons in clean conditions at a fraction of the time and cost of other experiments. Muons are simple like electrons but far heavier and thus capable of higher-energy collisions. Critics say such a machine is still far beyond our current technical abilities. But while it may be a technological moonshot, a muon collider offers the prospect of a precision instrument that could also potentially turn up evidence of new particles beyond the Standard Model’s.

Rubbia has spent most of his long career at CERN, including a five-year stint as director-general beginning in 1989. He has also taken a leadership role at Gran Sasso National Laboratory in his native Italy, which is looking for signs of the decay of the proton. (If seen, this would also offer clues about physics beyond the Standard Model.) An engineer and constant inventor, Rubbia has spent part of the last three decades pursuing radically novel energy sources — such as a nuclear power reactor that is driven by a particle accelerator.

Quanta caught up with Rubbia last month at the 69th Lindau Nobel Laureate Meeting in Germany. There, he addressed hundreds of young scientists from around the world, making the case for a muon collider as the best bet for learning more about the universe’s fundamental building blocks. A sharply dressed man with piercing blue eyes, he spoke with zeal, both onstage and off. The interview has been condensed and edited for clarity.

You discovered the W and the Z bosons. Why was this an important discovery?

Ha! I’ve never heard such a question! Particle accelerators are an essential part of the scientific program, which is fundamentally curiosity driven. And the discovery of the W and the Z bosons was one conclusion in the very long history of particle physics. There are particles of matter, like quarks and leptons, and those were reasonably well settled experimentally, but the question of the forces — that is, the particles which mediate the interactions between particles of matter — was something yet to be understood.

Now, the W and Z were postulated and discussed by many people, but the experimental realization required very high energies — for the time, at least. Don’t forget these fundamental choices are coming from nature, not from individuals. Theorists can do what they like, but nature is the one deciding in the end.