Bloomberg Distinguished Professor Adam Riess is one of four co-investigators now working on a European Research Council Synergy Grant entitled “Red teaming the H0 tension,” or “RedH0T,” to support international collaborative work on resolving the Hubble tension. Hubble tension is one of the outstanding challenges of modern cosmology and the reason for discrepancies when quantifying the expansion rate of the universe. 

The other principal investigators on the Synergy Grant are Julien Lesgourgues (Aachen University) and Licia Verde and Frederic Corbin (Barcelona). The grant will provide funding of more than 14 million dollars and will support postdocs and students of the collaborating institutions.

RedH0T aims to answer one of the challenges that cosmology has been facing for years: is the significant discrepancy between measurements of the Hubble constant (H0) due to observational errors or limitations of the current cosmological model? If the answer is the second explanation, scientists would be facing one of the most significant discoveries of the 21st century, with profound implications for fundamental physics.

The project also stands out for its innovative approach, pioneering in cosmology. RedH0T incorporates the red-teaming method, inspired by the field of cybersecurity. In the field of cybersecurity, to test the effectiveness of systems, ethical hackers carry out a simulated and non-destructive cyberattack. In our case, we intend that each methodology for measuring the Hubble constant be analyzed by three different teams, which will allow us to validate or question each method with maximum transparency and rigor, promoting scientific consensus, collaborative work will be developed by a blue team, made up of experts who will develop the methodology; a red team, made up of specialists who will challenge assumptions and look for vulnerabilities; and finally by a white team, who will be neutral participants who will oversee the process.

Despite the spectacular success of the standard cosmological model over the past two decades, recent observations and distance measurements with a wide range of cosmological instruments suggest cracks in this scientifically accepted paradigm. Differences have emerged in the measurements of quantities (tensions) that the current cosmological model predicts to be equal. The most important tension has to do with the Hubble parameter, which quantifies the expansion of the universe, about 13 billion years after the big bang.

In addition to RedH0T, 65 research groups have been awarded Synergy Grants by the European Research Council that will total more than 684 million euros in scientific funding.