An international team led by researchers from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) has received a Synergy Grant from the European Research Council to resolve the Hubble tension, one of the major challenges in modern cosmology and a source of disagreement when measuring the expansion rate of the universe. The project, called RedH0T, will receive more than €12 million in funding (around €6 million allocated to the UB).
Licia Verde, ICREA researcher and Scientific Director of ICCUB, is the coordinator of RedH0T. This project’s principal investigators also include Frédéric Courbin, ICREA researcher at ICCUB and the Institute of Space Studies of Catalonia (IEEC); Julien Lesgourques, from Aachen University (Germany) and Adam Riess, from Johns Hopkins University (United States), winner of the 2011 Nobel Prize in Physics for demonstrating that the expansion of the universe is accelerating.
“RedH0T aims to address one of the challenges that cosmology has faced for years: Is the significant discrepancy between measurements of the Hubble constant (H₀) caused by observational errors or limitations of the current cosmological model? If the latter is true, we would be facing one of the most significant discoveries of the 21st century, with profound implications for fundamental physics,” says Licia Verde.
The researcher adds: “RedH0T is expected to improve on all current measures of H₀ with cross-checks and internal consistency, thereby producing robust results that can guide cosmologists in revising the current paradigm.”
The project also stands out for its innovative approach, which is pioneering in cosmology. RedH0T introduces the red-teaming method, inspired by cybersecurity. “In the field of cybersecurity, ethical hackers conduct simulated, non-destructive cyberattacks to test the effectiveness of systems. In our case, we want each methodology for measuring the Hubble constant to be analysed by three different teams, which allows each method to be validated or questioned with maximum transparency and rigour, promoting scientific consensus,” says Fred Courbin.
This collaborative work will be carried out by a blue team, made up of experts who will develop the methodology; a red team, composed of specialists who will challenge assumptions and look for vulnerabilities; and a white team, with neutral figures who will oversee the process.
International institutions in pursuit of an ambitious goal
In addition to the University of Barcelona (project coordinator), Aachen University and Johns Hopkins University, the Alma Mater Studiorum - University of Bologna, The Chancellor Masters and Scholars of the University of Oxford and the University of Chicago are also participating in the project. The team from the UB’s Institute of Cosmos Sciences is completed by Raúl Jiménez-Tellado (ICREA-ICCUB) and Héctor Gil-Marín (ICCUB-IEEC).
RedH0T and the current cosmological model
Despite the remarkable success of the standard cosmological model over the last two decades, recent observations and distance measurements using a wide range of cosmological instruments suggest cracks in this scientifically accepted paradigm. Differences have appeared in the measurements of quantities (tensions) that the current cosmological model predicts to be equal. The most prominent tension concerns the Hubble parameter, which quantifies the expansion of the universe approximately 13 billion years after the Big Bang.
The goal of solving this cosmological challenge has been recognized with a Synergy Grant, a grant from the European Research Council that supports teams of two to four researchers to tackle research projects that require deep collaboration across different disciplines. In this call, 66 research groups have been recognized and will receive €684 million in funding.
