It has been held at Como – Villa del Grumello, 23-27 June, the 2025 edition of the “Lake Como Schools on Astrophysics, Cosmology and Gravitation” on the theme “Dark Matter, Dark Energy and the Cosmological Tensions”.

These Schools are directed to PhD students and young Post-Docs in Physics, Astronomy and Mathematics who are interested in widening their knowledge in the fields of Physical Cosmology, Relativistic Astrophysics, General Relativity, Experimental Gravity and the Modern Quantum Theories of Gravitation.

The theme selected for the School considers a dilemma that today cosmology and astrophysics are experiencing: on one side, we have a very successful model, the ΛCDM model, able to adjust to almost all observations. On the other hand, such a model requires 96% of stuff about whose nature we have yet no certain knowledge: 26% of dark matter and 70% of dark energy, with only 4% left for the known matter, mostly in the form of hydrogen and helium nuclei. While dark matter seems to be necessary to explain the formation and the dynamics of galaxies and of larger structures, such as galaxy clusters and super clusters, dark energy is required to explain why our universe is in a state of accelerated expansion. The school aims at providing master’s and doctoral students and young post doctoral researchers with a perspective on the most important proposals on the nature of the dark components of the universe, not only from the theoretical point of view, but also from the experimental and observational one.

A significant number of students, both from Italy and abroad, participated to the School (co-funded by INAF Scientific Direction together with other Research Institutions and Universities), with a rare opportunity: a truly ‘wide field’ perspective on this theme. It has been indeed a precise choice of the Scientific Committee to include as many points of view as possible, from the more canonical to the more contentious. The lectures have been estremely interesting, from the standard cosmological model and its possible extensions to theoretical hypotheses and experimental searches on the origin of dark matter and energy, observational constraints on Hubble Constant and other fundamental cosmological parameters, the phenomenology in support of general relativity, alternative theories of gravitation.

The lectures given at the School:

• Elena Aprile (Columbia University, USA) and Elisabetta Barberio (University of Melbourne, Australia) – The search for dark matter
• Indranil Banik (University of Portsmouth, UK) – The local supervoid solution to the Hubble tension
• Karl van Bibber (UC Berkeley, USA) – Axion and axion-like particle dark matter
• Filipe Costa (Minho University, Portugal) – Astronomical reference systems in the framework of General Relativity
• Mariateresa Crosta (INAF, Turin, Italy) – Dark Matter as a possible effect of General Relativity
• Joshua A. Frieman (University of Chicago, USA) – Dark Energy: Theory and Observations
• Brenda L. Frye (University of Arizona, USA) – Measuring the Hubble–Lemaître Constant by Time Delay Cosmography
• Asta Heinesen (Bohr Institute, Denmark) – Backreaction from inhomogeneities
• Ruth E. Kastner (University of Maryland, USA) – Transactional Entropic Gravity and MOND
• Pavel Kroupa (University of Bonn, Germany) – Cosmological models based on MOND
• Andrea Lapi (SISSA, Italy) – Stochastic approach to dark energy
• Roberto Peron (INAF, Rome, Italy) – Precision tests of GR in the Solar System
• Joseph Silk (University of Oxford, UK) – Gamma ray probes of dark matter in galaxies and primordial black holes as dark matter
• Constantinos Skordis (CEICO, Czech Republic) – Extensions of General Relativity and cosmological dark matter
• Sandro Tacchella (University of Cambridge, UK) – The newest from JWST: implications for cosmology and galaxy formation
• Tim Tait (UC Irvine, USA) – Building realistic models of dark matter
• Michael Turner (University of Chicago, USA) – The big cosmological picture and the big open questions