Indianapolis, Indiana – In a major leap toward understanding why the universe exists at all, scientists at Indiana University (IU) have helped uncover new insights into one of the universe’s most mysterious and fundamental particles — the neutrino. Through a groundbreaking international collaboration between two leading experiments, researchers have taken a critical step toward explaining why matter, not nothingness, dominates the cosmos.
The discovery, published in the journal Nature, represents a first-of-its-kind joint analysis between the NOvA experiment in the United States and T2K in Japan. Both are massive scientific efforts designed to study how neutrinos — tiny, nearly massless particles that constantly stream through space — change as they travel. By combining their results, the two research teams have been able to extract new clues about how neutrinos and their antimatter counterparts behave differently, potentially revealing why the universe didn’t vanish in a flash of energy right after the Big Bang.
An Invisible Key to Existence
Neutrinos are among the strangest residents of the subatomic world. They are everywhere — trillions pass through every person on Earth each second — yet they almost never interact with anything. They have no electric charge and an almost imperceptible mass, making them elusive even for the most sophisticated detectors. But within their invisibility may lie answers to some of the deepest mysteries of existence.
Physicists have long struggled to understand why the universe is filled with stars, galaxies, and living things instead of being empty. The laws of physics suggest that when the Big Bang occurred, it should have created equal amounts of matter and antimatter — mirror-image versions of each other. When these two meet, they annihilate, releasing energy and leaving nothing behind. Yet, for reasons still unknown, something tipped the scales in favor of matter.
That imbalance allowed everything we see today to form — from dust clouds and planets to oceans and life. Neutrinos, it turns out, might hold the key to this cosmic mystery.
The Experiments That Saw the Unseeable
Both NOvA and T2K are massive international undertakings that aim to study how neutrinos “oscillate,” or change form, as they travel. Neutrinos come in three “flavors” — electron, muon, and tau — and can transform between these identities as they move. The way they shift, and whether those transformations differ from their antimatter versions (called antineutrinos), could explain why matter triumphed over antimatter.
In the NOvA experiment, scientists at Fermilab near Chicago send a beam of neutrinos 810 kilometers through the Earth to a gigantic 14,000-ton detector in Ash River, Minnesota. Meanwhile, in Japan, the T2K experiment fires neutrinos from the J-PARC accelerator in Tokai to the enormous Super-Kamiokande detector buried beneath Mount Ikenoyama — a 295-kilometer journey through solid rock.
Each setup captures only a handful of neutrino interactions out of trillions that pass through undetected. But when analyzed collectively, those rare events reveal astonishing patterns.
By merging their data, the NOvA and T2K teams have managed to reach a level of precision that neither could achieve alone. Their joint analysis improves scientists’ ability to measure how neutrinos oscillate and how much they deviate from what is expected under the rules of CP symmetry — the principle that matter and antimatter should behave as perfect opposites.
In reality, however, that symmetry appears to be broken.
A Universe That Chose Matter
The study’s findings indicate a subtle but significant difference in how neutrinos and antineutrinos oscillate — a violation of CP symmetry. In essence, neutrinos may not act like their mirror-image counterparts. That tiny asymmetry, multiplied across the vast energy scales of the early universe, might have prevented total annihilation and allowed matter to persist.
It’s a stunning possibility: that the reason everything exists — every atom, planet, and galaxy — may trace back to the peculiar behavior of these ghostly particles.
“We’ve made progress on this really big, seemingly intractable question: why is there something instead of nothing?” said Professor Mark Messier, Distinguished Professor and Chair of the Physics Department at IU Bloomington. “And, we’ve set the stage for future research programs that aim to use neutrinos to tackle other questions.”
Messier, a longtime leader in neutrino research, has been part of the NOvA project since 2006 and played a major role in coordinating this collaborative analysis. He was joined by fellow IU physicists Jon Urheim, James Musser (Emeritus), Stuart Mufson (Emeritus), and Jonathan Karty from the Department of Chemistry. Their work underscores IU’s long-standing reputation as a global leader in particle physics.
A Triumph of Teamwork and Technology
The breakthrough wasn’t just a scientific feat — it was also a triumph of collaboration across continents. The combined effort includes hundreds of researchers from the United States, Japan, and more than a dozen other countries.
According to Nature’s press release, “Combining the analyses takes advantage of the complementary sensitivities of the two experiments and demonstrates the value of collaboration.”
NOvA’s long-distance beam offers insight into how neutrinos behave as they travel vast distances through Earth, while T2K’s shorter but more intense beam provides finer detail about their oscillations. Together, these experiments form a more complete picture of how neutrinos evolve — and how they might have tipped the cosmic scales billions of years ago.
IU’s involvement highlights how large-scale scientific partnerships can yield results that no single institution could achieve alone. The joint study was supported by funding from the U.S. Department of Energy, whose support underscores the importance of investing in fundamental science.
“There has been transformative technological innovation across all sectors of society that’s come out of high-energy physics,” said Messier. “Further, next-generation scientists immerse themselves in data science, in machine learning, artificial intelligence, and in electronics, and then go into industries with the deep skills they’ve gained while trying to answer these really difficult questions.”
The technologies developed to detect neutrinos — such as ultra-fast electronics, high-resolution sensors, and advanced data analysis tools — have already influenced fields ranging from medical imaging to materials science.
Indiana University’s Ongoing Legacy
IU’s role in this discovery continues a proud tradition of pioneering contributions to physics. Over the decades, the university has played a vital role in particle detector design, data interpretation, and the education of new scientists who now contribute to major research centers worldwide.
Among those advancing the neutrino frontier are IU Ph.D. students Reed Bowles, Alex Chang, Hanyi Chen, Erin Ewart, Hannah LeMoine, and Maria Manrique-Plata, all of whom have contributed to the joint NOvA-T2K research. For many of these young scientists, the collaboration represents not just a career milestone, but an entry point into the next era of discovery.
Messier and his colleagues have also supervised numerous undergraduate and graduate students since NOvA began operations in 2014, helping them gain hands-on experience with some of the most complex scientific equipment ever built.
The Next Frontier
The implications of this research stretch far beyond the lab. By revealing how neutrinos break expected rules of symmetry, scientists can begin to test new models of physics that go beyond the Standard Model, the framework that currently describes all known particles and forces.
Future experiments — such as DUNE (Deep Underground Neutrino Experiment), now under construction in the U.S., and Hyper-Kamiokande in Japan — will build on the foundation laid by NOvA and T2K. These massive next-generation detectors aim to capture even more detailed evidence of how neutrinos behave, potentially confirming that these tiny particles truly hold the answer to why the universe exists.
“As a physicist I find it fascinating that a huge question, like why there’s matter in the universe instead of antimatter, can be broken down into smaller, step-by-step questions,” said Messier. “Instead of being dumbstruck by the enormity of it, we can actually make progress toward an answer about why we’re here in the universe.”
Why It Matters
Beyond the abstract allure of understanding the cosmos, this work reflects something deeply human — our need to know why we exist at all. The joint effort between scientists at Indiana University and collaborators across the globe embodies how shared curiosity and cooperation can push the boundaries of knowledge.
From deep underground labs in Minnesota and Japan to classrooms and computer clusters in Bloomington, the pursuit of neutrino science connects people across borders, languages, and generations. Each new insight into these elusive particles brings humanity a little closer to grasping its origins — and perhaps, its destiny.
What began as a question about invisible particles may ultimately illuminate the most profound mystery of all: how a universe of matter, life, and light emerged from the symmetry of nothingness.
