When it comes to understanding the universe, what we know is only a sliver of the whole picture. Dark matter and dark energy make up about 95% of the universe, leaving only 5% "ordinary matter," or what we can see. Dr. Rupak Mahapatra , an experimental particle physicist at Texas A&M University, designs highly advanced semiconductor detectors with cryogenic quantum sensors, powering experiments worldwide and pushing the boundaries to explore this most profound mystery.
Mahapatra likens our understanding of the universe — or lack thereof — to an old parable: "It's like trying to describe an elephant by only touching its tail. We sense something massive and complex, but we're only grasping a tiny part of it."
He and co-authors are featured in the prestigious journal Applied Physics Letters .
What are dark matter and dark energy?
Dark matter and energy are so named because what they are comprised of is unknown. Dark matter accounts for most of the mass in galaxies and galaxy clusters, shaping their structure on the largest scales. Dark energy, on the other hand, refers to the force driving the universe's accelerated expansion. In other words, dark matter holds things together, while dark energy is pulling them apart.
Despite their abundance, neither emits, absorbs or reflects light, making them nearly impossible to observe directly. Yet, their gravitational effects shape galaxies and cosmic structures. Dark energy is even more dominant than dark matter: it makes up about 68% of the universe's total energy content, while dark matter is about 27%.
Detecting whispers in a hurricane
At Texas A&M, Mahapatra's group is building detectors so sensitive they can pick up signals from particles that interact rarely with ordinary matter, signals that could reveal the nature of dark matter.
"The challenge is that dark matter interacts so weakly that we need detectors capable of seeing events that might happen once in a year, or even once in a decade," Mahapatra said.
The team contributed to a world-leading dark matter search using a detector called TESSERACT. "It's about innovation," he said. "We're finding ways to amplify signals that were previously buried in noise."
Texas A&M is part of a select group of institutions working on the TESSERACT experiments.
Pushing the limits of what's possible
Mahapatra's work builds on a long history of pushing detection limits, with world-leading searches through his participation in the SuperCDMS experiment for the past 25 years. In a landmark 2014 paper in Physical Review Letters , he and collaborators introduced voltage-assisted calorimetric ionization detection in the SuperCDMS experiment — a breakthrough that allowed researchers to probe low-mass WIMPs , a leading dark matter candidate. This technique dramatically improved sensitivity for particles that were previously beyond reach.
More recently, in 2022, Mahapatra co-authored a study exploring complementary detection strategies — direct detection, indirect detection and collider searches for a WIMP. This work underscores the global, multi-pronged approach to solving the dark matter puzzle.
"No single experiment will give us all the answers," Mahapatra notes. "We need synergy between different methods to piece together the full picture."
Understanding dark matter isn't just an academic exercise, it's key to unlocking the fundamental laws of nature. "If we can detect dark matter, we'll open a new chapter in physics," Mahapatra said. "The search needs extremely sensitive sensing technologies and it could lead to technologies we can't even imagine today."
What Are WIMPs?
WIMPs (Weakly Interacting Massive Particles) are one of the most promising candidates for dark matter. They're hypothetical particles that interact through gravity and the weak nuclear force, making them incredibly hard to detect.
- Why they matter: If WIMPs exist, they could explain the missing mass in the universe.
- How we search: Experiments like SuperCDMS and TESSERACT use ultra-sensitive detectors cooled to near absolute zero to catch rare interactions between WIMPs and ordinary matter.
- The challenge: A WIMP might pass through Earth without leaving a trace, so scientists need years of data to spot even a single event.
By Lesley Henton, Texas A&M University Division of Marketing and Communications
