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Dark matter interactions may be a hidden “dark force,” unexpectedly constraining our Universe’s expansion and structural development, according to researchers.

In a recent paper published in the Journal of Cosmology and Astroparticle Physics, researchers identified unexpected effects arising from dark matter particles interacting with one another and clustering via a hidden dark force.

Typically, scientists can only study the invisible—and still purely theoretical—dark matter through its gravitational effects on ordinary matter. However, the new research explores how dark matter may also influence itself.

Exploring the Dark Force

As scientific instruments become more precise, researchers continue to uncover mysteries once hidden at the fuzzy edges of our understanding of the cosmos. One such puzzle involves discrepancies in measurements of the Universe’s density over time. Within the widely accepted ΛCDM model of cosmology, observations of cosmic expansion and the growth of large-scale structures have not always aligned with theoretical expectations.

To address these tensions, researchers have proposed a theoretical dark force—a previously unrecognized attractive force that acts only between dark matter particles. Such a force could influence both the expansion of the Universe and the formation of cosmic structures, potentially helping reconcile current models with recent observations.

“What we really know about dark matter has so far been learned only through its gravitational effects,” said co-author Zachary Weiner, a researcher at the Perimeter Institute for Theoretical Physics. “That leaves open the possibility that dark matter might have additional interactions that are hidden from ordinary matter.”

Investigating the Dark Force

The researchers examined models in which dark matter particles interact through a long-range force beyond gravity. By combining cosmological observations with theoretical calculations, they searched for evidence of how such a force might affect both the growth of cosmic structures and the expansion history of the Universe.

At first glance, the prediction seemed straightforward: if an additional attractive force pulls dark matter particles together, it should enhance their ability to cluster, potentially explaining why some observations suggest a denser cosmic landscape than expected.

“The first thing you would expect is that giving dark matter an additional attractive force should make structures grow faster,” Weiner explained. “But another effect comes into play at the same time.”

A Surprising Discovery

The researchers’ results revealed a more complicated picture. While a dark force does cause dark matter to cluster more efficiently, it also alters the expansion of the Universe in a way that causes dark matter particles to become effectively lighter over time.

As a result, the additional clustering is not strong enough to significantly increase matter’s gravitational imprint on the cosmic microwave background. Instead, the net effect is to suppress the overall growth of cosmic structure.

According to the researchers, this previously unrecognized interaction could play an important role in new cosmological models developed to explain observations from the Dark Energy Spectroscopic Instrument (DESI) in Tucson, Arizona. If confirmed, the effects of a dark force may need to be incorporated into future efforts to understand the evolution of the Universe.

As astronomers peer farther into space and deeper into cosmic history with ever-greater precision, studies like this may help explain subtle discrepancies that have long remained hidden.

“The Universe is often more subtle than our intuition,” Weiner concluded. “That’s exactly why we have to keep testing these ideas.”

The paper, “Dark Forces Suppress Structure Growth,” appeared in the Journal of Cosmology and Astroparticle Physics on June 22, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.

The University of Louisville (UofL), in partnership with UofL Health and Kosair for Kids, has officially inaugurated the newly expanded Kosair for Kids Center for Pediatric NeuroRecovery. This groundbreaking facility represents a significant advancement in the field of pediatric rehabilitation, merging cutting-edge clinical care, innovative therapy, and pioneering research into a unified environment specifically designed to enhance recovery outcomes for children affected by spinal cord injuries and other neurological disorders. Situated within the UofL Health – Frazier Rehabilitation Institute, the center now boasts a sprawling 13,631-square-foot space meticulously crafted to foster accelerated healing and broader access to vital therapies.

This state-of-the-art expansion is not merely architectural; it symbolizes a transformative shift in pediatric neurorehabilitation capabilities. UofL President Gerry Bradley emphasized the tangible nature of this shift, highlighting that the center transcends former promises to become a beacon of hope that materially improves children’s recovery journeys. The new facility’s design actively promotes multidisciplinary collaboration among clinicians, therapists, researchers, and families — a factor crucial to advancing the efficacy and personalization of neurorehabilitative treatments.

A chief driver of this innovation is a vibrant integration of clinical care and research. For more than ten years, the Kosair for Kids Center has led the nation in pediatric neurorecovery services, evolving from a modest facility serving a single child daily to one conducting over 20 specialized therapy sessions each day. The current expansion increases treatment capacity by approximately 33%, enabling up to 24 children daily to benefit from intensive, tailored neurorehabilitation interventions that are informed by the latest scientific insights.

Andrea Behrman, the center’s director and a professor in UofL’s Department of Neurological Surgery, underlined the importance of this alignment between infrastructure and innovation. The new environment mirrors the pioneering nature of the center’s clinical research and treatment methodologies, allowing for an integrated therapeutic model that advances the continuum from laboratory breakthroughs to bedside applications. This seamless interaction ensures rapid translation of novel neurorehabilitation techniques into practical therapy regimens that can dramatically enhance neural plasticity and functional recovery in pediatric patients.

A pivotal element of the expanded center’s capability stems from its sophisticated therapeutic technologies tailored specifically for children and adolescents. Unlike adult neurorehabilitation, pediatric therapy demands nuanced modifications to account for developmental neurobiology and psychosocial factors. As such, the center incorporates advanced rehabilitation equipment and adaptive devices engineered to stimulate neurological reorganization during critical windows of neural development, thereby fostering improved motor function, sensory integration, and cognitive processing in young patients.

Fundamental to the center’s growth was the philanthropic contribution of Kosair for Kids, which provided a $1 million grant, supplemented by $2 million in federal funding from the Health Resources and Services Administration and additional donations. This financial backing was instrumental in not only expanding physical capacity but also in updating and acquiring cutting-edge research and therapeutic tools. Such investments underpin the center’s ability to deliver innovative care protocols that emphasize high-intensity, task-specific therapies designed to maximize neuroregenerative potential.

The expansion also incorporates specialized spaces that support both patients and their families. Recognizing the essential role of caregivers in neurorecovery, the facility includes private consultation rooms designed to facilitate comprehensive communication between families and multidisciplinary teams. Moreover, family-centered common areas foster a supportive atmosphere conducive to emotional well-being, which is increasingly acknowledged as a critical component of successful rehabilitation.

Federal support for this project underscores the national importance of pediatric neurorehabilitation research and clinical excellence. Contributions from policymakers, including Congressman Morgan McGarvey and former Congressman John Yarmuth, were vital in securing funds that helped realize this vision. Additionally, the estate bequest from Jane Burian, commemorating Dr. Frank J. Burian and Henrietta S. Burian, ensures enduring legacy funding for the center’s mission, promoting sustainability of its impact on children’s health.

The Kosair for Kids Center also functions as an academic hub, training the next generation of therapists, neurologists, and researchers. Its integrated model provides a unique educational resource, combining real-time clinical exposure with hands-on research opportunities. This prepares healthcare professionals to implement evidence-based, pediatric-specialized neurorehabilitation strategies that address the complex neurological needs of children recovering from spinal injuries and similar conditions.

The therapeutic modalities employed at the center are grounded in a robust research framework maintained by the Kentucky Spinal Cord Injury Research Center. This alliance facilitates translational research whereby inventions, from neuroprosthetics to neurostimulation paradigms, are tested and refined under clinical conditions. Such synergy accelerates the progression from theoretical neuroscience advancements to tangible improvements in pediatric patient outcomes—rendering UofL an international leader in this specialized field.

Notably, the expansion’s infrastructure supports novel neuroimaging, biomarker analysis, and neurophysiological monitoring techniques. These technological capabilities enable real-time assessment of neural recovery trajectories and therapy efficacy, allowing clinicians to tailor interventions dynamically. This personalized medicine approach marks a paradigm shift in pediatric neurorehabilitation, moving away from generalized treatment plans toward evidence-driven, patient-specific therapies with higher likelihood of success.

Financial access remains a priority, with ongoing support from the Shelley Trimble Fund for Pediatric NeuroRecovery easing the economic burden on families by subsidizing treatments irrespective of insurance hurdles. This commitment ensures equity in care delivery and maximizes the potential reach and societal impact of the center’s trailblazing work, making life-altering neurorecovery therapies available to a broader pediatric population vulnerable to neurological injury.

In sum, the newly expanded Kosair for Kids Center for Pediatric NeuroRecovery at UofL represents a transformative advancement in pediatric neurorehabilitation, seamlessly fusing clinical excellence, avant-garde research, and compassionate family-centered care. Its innovative design and groundbreaking therapeutic approaches position it at the vanguard of efforts to rewrite the trajectories for children recovering from spinal cord injuries and neurological disorders—with hope that this model will inspire similar advances on a global scale.

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Subject of Research: Pediatric NeuroRecovery and Rehabilitation of Spinal Cord Injuries and Neurological Conditions in Children

Article Title: University of Louisville Unveils State-of-the-Art Kosair for Kids Center for Pediatric NeuroRecovery, Accelerating Advances in Pediatric Rehabilitation and Research

News Publication Date: Not provided

Web References:

• Kosair for Kids Center for Pediatric NeuroRecovery
• Frazier Rehabilitation Institute Pediatric NeuroRecovery Services
• Kentucky Spinal Cord Injury Research Center

Image Credits: University of Louisville / Tom Fougerousse

Keywords

Pediatric NeuroRecovery, Spinal Cord Injury, Pediatric Rehabilitation, Neurological Disorders, Neuroplasticity, Translational Research, UofL Health, Kosair for Kids, Clinical Care Innovation, Pediatric Therapy Technology, Neurological Surgery, Child Neurorehabilitation

A fresh analysis of Type Ia supernovae overturns a controversial 2025 claim that cosmic expansion is slowing.

The post New Supernova Study Confirms Universe’s Expansion is Still Accelerating appeared first on Sci.News: Breaking Science News.

In a remarkable advancement that promises to redefine materials science, researchers have developed an extraordinary crystal exhibiting isotropic zero thermal expansion (ZTE) across an unprecedentedly wide temperature range. This pioneering work focuses on a sodalite-structured compound, Cd4Al6O12SO4, abbreviated as CASO, which maintains near-perfect dimensional stability from cryogenic temperatures as low as 11 K up to an exceptional 893 K. Such a feat addresses one of the most persistent challenges in materials engineering—achieving consistent, isotropic ZTE behavior over a broad thermal window, well beyond the typical operating limit of 400 K commonly found in existing materials.

Thermal expansion, the tendency of materials to expand or contract in response to temperature changes, significantly influences the reliability and precision of components in advanced technological systems. This is particularly critical in optics, aerospace, and microelectronics, where slight dimensional deviations can lead to catastrophic failures or degraded performance. Traditionally, materials exhibiting zero or near-zero thermal expansion either operate within narrow temperature bands or display anisotropic expansion, complicating their practical application. CASO emerges as a groundbreaking solution by combining flexibility and robustness within a closed-framework sodalite structure, a geometry celebrated for its remarkable stability.

What sets CASO apart is the ingenious incorporation of flexible interstitial groups realized via fractionally occupied atoms nestled within the sodalite framework. This strategic design introduces subtle positional disorder among ligand atoms, a feature that amplifies transverse atomic vibrations responsible for generating negative thermal expansion. These enhanced transverse vibrations effectively counterbalance the intrinsic positive thermal expansion that arises from atomic lattice expansion at elevated temperatures. As a result, CASO achieves a finely tuned, cancellatory interplay between positive and negative thermal expansion mechanisms, yielding an overall coefficient of thermal expansion measured at a negligible 0.21(23) × 10^−6 K^−1.

The research team’s exploration of CASO’s structural integrity under rigorous thermal cycling reveals impressive resilience, with the material maintaining its crystalline structure up to 1,100 K. This high thermal threshold expands the operational capacity of ZTE materials into regimes previously inaccessible, paving the way for applications in extreme thermal environments such as space exploration technologies and high-temperature sensor systems. Importantly, the integrity of CASO at such elevated temperatures also suggests potential advancements in engineering components that must endure thermal shocks without suffering deformation or failure.

Beyond mechanical stability, CASO exhibits a solar-blind ultraviolet (UV) transparency window extending down to 275 nm. This optical property signifies that the material can transmit UV light within this range without absorption, rendering it valuable for specialized UV optics and photonics applications. Devices requiring minimal optical noise and high stability, such as spaceborne UV detectors and precision laser optics, stand to benefit from CASO’s unique optical-transparency combined with its unparalleled thermal stability.

Optical materials are notoriously susceptible to thermal fluctuations, which induce refractive index changes and distort beam paths, complicating precision measurements and laser operations. CASO’s thermally induced optical fluctuations are at least twice as low as those found in conventional optical media, an achievement that underscores its potential to revolutionize precision optics. This property not only enhances the performance of existing systems but also reduces the need for complex compensatory mechanisms, simplifying designs and improving reliability in challenging thermal environments.

Substantially, CASO’s isotropic ZTE capacity challenges and expands the conventional understanding of thermomechanical behavior in framework materials. The sodalite structure itself provides a three-dimensional network that constrains thermal responses isotropically, a feature critical for applications demanding uniform response in all spatial directions. The partial occupation and flexibility of interstitial species suggest new dimensions of control over lattice dynamics and open pathways for tailored ZTE behavior through chemical modification and structural engineering.

The discovery underscores the significance of lattice dynamics modulation via controlled disorder—a concept that holds promise far beyond ZTE materials. Manipulating atomic vibrational modes through fractional occupancy and positional disorder reshapes how scientists can exploit negative thermal expansion while mitigating positive expansion, with implications for diverse fields from thermal barrier coatings to quantum materials.

Moreover, the work by Liu, Jiang, Molokeev, and colleagues establishes a universal strategy for engineering ZTE materials, thus serving as a blueprint for future crystal design. Rather than relying on complex composites or layered heterostructures, this approach leverages the intrinsic vibrational characteristics and flexibility within single-phase crystals. Such simplicity in design may accelerate industrial adoption and reduce costs associated with fabricating advanced thermal-stable materials.

The implications of this discovery are profound for the electronics and precision engineering industries. Components fabricated from CASO could maintain micron-scale tolerances across vast thermal gradients, thereby improving the longevity and performance of microelectromechanical systems (MEMS), precision optics, and high-frequency electronic devices. The broad temperature stability and isotropy also alleviate challenges associated with thermal mismatch and interface stresses in multilayered devices.

In addition to immediate technological applications, CASO’s unique properties may spur new scientific inquiries into the fundamental physics of thermal expansion. Investigating how flexible ligand atoms interact within complex frameworks provides insights into phonon dynamics, anharmonic lattice vibrations, and thermodynamic stability. This research advances theoretical models and computational simulations aiming to predict and control thermal properties at the atomic scale.

As society increasingly demands materials that withstand extreme environmental conditions without compromising structural or optical performance, CASO stands as a beacon of hope and innovation. Its extended temperature operational window combines mechanical robustness, optical transparency, and thermal stability into a single crystalline phase—attributes that are rarely coexistent. This convergence could lead to breakthroughs in harsh-environment sensors, satellite optics, and next-generation aerospace components.

Furthermore, the concept of embedding fractionally occupied flexible groups within stable frameworks could be extrapolated to customize other physical properties such as thermal conductivity, dielectric constants, and even magneto-thermal behavior. This multifunctionality potential situates CASO not just as a material of the present, but as a foundation for multifunctional crystals engineered at the atomic level for bespoke applications.

In conclusion, CASO embodies a paradigm shift in thermal expansion control, marrying structural ingenuity with atomic-scale dynamism. Its validation as an isotropic zero thermal expansion material from cryogenic to near-1100 K temperatures resolves a longstanding challenge and invites a new era of functional materials science. This elegant interplay of lattice architecture and vibrational physics heralds a future where materials no longer passively endure thermal fluctuations but actively neutralize them, ushering in unprecedented precision and resilience in advanced technologies.

Such groundbreaking discoveries, as reported by Liu and colleagues in Nature Chemistry, showcase the transformative power of crystal engineering and vibrational control. The research propels us beyond incremental advances to a realm where materials can be custom-tuned for the harshest and most demanding environments known to science and industry, reshaping what is possible across technological frontiers.

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Subject of Research: Isotropic zero thermal expansion properties in a sodalite-structured crystal (Cd4Al6O12SO4, CASO) across an exceptional temperature range.

Article Title: Isotropic zero thermal expansion in sodalite crystals from 11 to 893 K.

Article References:
Liu, Y., Jiang, X., Molokeev, M.S. et al. Isotropic zero thermal expansion in sodalite crystals from 11 to 893 K. Nat. Chem. (2026). https://doi.org/10.1038/s41557-026-02174-x

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41557-026-02174-x

A new study has taken a fresh look at a late 2025 Yonsei University study claiming the universe’s expansion is stalling out and instead has found that the universe is still expanding as previously believed.

Led by researchers from the University of Southampton, the team behind the new analysis acknowledged the scientific value of the 2025 team’s work, noting that their calculations were not wrong but lacked the additional data needed to confirm the universe’s expansion rather than refute it.

The lead author of the 2025 study, Dr. Chul Chung, told The Debrief that he and his colleagues “have already submitted our response to Wiseman, Riess et al. 2026 on May 14,” adding that the paper, “Still accelerating: age bias correction in supernova cosmology is robust to host-progenitor age mapping,” has also been posted on arXiv.

“The abstract summarizes the two main issues we identify in Wiseman et al., so I think it provides a concise overview of our position,” Chung told The Debrief.

Challenging Universal Expansion

According to a statement announcing the findings, scientists first confirmed the universe’s expansion was accelerating in 2011, a discovery that won astrophysicists Professor Adam Riess and Professor Brian Schmidt the Nobel Prize in Physics. Since that discovery, cosmological models have incorporated this accelerating expansion, with experiments on dark matter and dark energy attempting to explain it.

Then last year, a separate team of astronomers announced that a new analysis of stellar phenomena indicated that the universe was no longer expanding. Adding to the controversy was the team’s claim that dark energy may not exist, citing the lack of concrete evidence for a universe undergoing accelerating expansion.

According to the Southampton-led team behind the new study, the 2025 study suggested that previous methods used to measure the universe’s expansion, such as measuring supernovae, “were fundamentally flawed.”

“This points to a time-varying dark energy and a universe that is no longer accelerating, representing a potential paradigm shift in cosmology if confirmed,” explained Professor Chul Chung, co-lead author on the study, in a 2025 email to The Debrief.

The claims sent shockwaves through the scientific community, a result that the researchers note could have dismantled the Nobel Prize-winning team’s historic findings, and “nearly three decades of astronomical progress.”

When discussing the 2025 team’s work, the lead author of the new study, Dr Phil Wiseman, said the team’s findings and the resulting debate were not necessarily incorrect. Instead, the Southampton researcher said it was primarily a result of a scientific understanding.

“The previous and well-accepted measurements were, in fact, fine and our current understanding of the fate of the universe remains robust.”

Recalculating Galaxy Masses and White Dwarf Star Ages Reestablishes Expansion

In their reanalysis, the Southampton-led team recalibrated the original data to account for variables not in the original study. According to Wiseman, these included “different host environments and populations.”

For example, the research team looked at Type 1a supernovae, which are violet, extremely bright explosions of white dwarf stars. The authors of the 2025 study claimed that this class of supernova had “different maximum brightness,” which had tricked astronomers into thinking the cosmos was accelerating, when their analysis said it was actually slowing down.

When they took a fresh look at the data, the Southampton team found that they had incorrectly estimated the age of these stars. The new study also says the 2025 team didn’t account for the mass of the galaxies hosting these cosmological phenomena, which they described as “a standard correction used in modern cosmology to prove accuracy.”

When his team factored those data points in, Wiseman said the evidence for a stalling expansion was not supported. Instead, the researcher observed that “the evidence for cosmic acceleration remains remarkably consistent.”

In their reply on ArXiv, the Yonsei University team said the new research failed to factor in two variables of their own, adding that “when these two effects are consistently combined in computing the redshift-dependent magnitude correction, the final correction, and hence the resulting cosmological impact, remain largely unchanged,” from the original 2025 calculations.

“Extraordinary Claims Require Especially Careful Testing”

When discussing the new study’s findings, Southampton Professor Mark Sullivan highlighted the benefits of scientific review, noting that “this is how progress is made.”

“Although this idea did not turn out correct, it has opened up new ways of thinking about how supernovae explode and how we can measure dark energy more accurately,” the researcher added.

Paper co-author, Dr Brodie Popovic agreed, noting that the 2025 study provided astronomers a good opportunity to “go back over all of our assumptions,” adding that “it turns out, yes, we do understand this stuff, and we’re accounting for it in our cosmology measurement.”

In a salute to the Sagan Standard established by astronomer Carl Sagan, which says “extraordinary claims require extraordinary evidence,” Reiss seemed to celebrate the new findings that reestablish his original work by quipping that “extraordinary claims require especially careful testing.”

With the accelerating expansion of the universe seemingly reestablished, at least for now, Dr Wiseman said: “we can get back to trying to understand what dark energy actually is, rather than wondering if it exists at all.”

“Thankfully we have averted this crisis, but the mystery about why the universe is still accelerating in size remains,” he added. 

The study “Still Accelerating: Type Ia supernova cosmology is robust to host galaxy age evolution” was published in Monthly Notices of the Royal Astronomical Society.

Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.