*NOBEL LECTURES*

**Gerard ‘t Hooft** 

*1999 Nobel Prize in Physics with his thesis advisor Martinus J. G. Veltman "for elucidating the quantum structure of electroweak interactions"*

has contributed to the major developments in fundamental theoretical physics of the last fifty years. Already in his PhD thesis, he renormalized the Yang-Mills theories, opening the way to electroweak theory, to quantum chromodynamics (theory of quarks), and finally to the Standard Model of elementary particles. He then turned his attention to Gravity, formulating in 1993 the Holographic Principle, which has been from then an illuminating guide for researchers in String Theory and Quantum Gravity. And, not least, in the last twenty years he developed his controversial deterministic interpretation of quantum mechanics, following the footsteps of Einstein. For these achievements he received many prizes, among which the Wolf Prize in 1981 and the Nobel Prize in Physics 1999.

**Roger Penrose**

*2020 Nobel Prize in Physics "for the discovery that black hole formation is a robust prediction of the general theory of relativity"*

revolutionized General Relativity in 1965, introducing new powerful topological techniques to study the singularity problem. With his younger colleague Stephen Hawking, he developed the famous singularity theorems: if General Relativity is true, there must be a space-time singularity in the past (the Big Bang), and there must be singularities in the future (black holes). Then, Penrose also made fundamental contributions to quantum theory, proposing that the (spontaneous) collapse of the wave function is due to gravitational interaction. Experiments are designed in these years to verify this hypothesis. In the early 1990s, he tackled the problem of consciousness, finding evidence for the non-algorithmic nature of the mind and therefore its non-reproducibility on a machine. Among the many prizes, he received the Wolf Prize in 1988, the Dirac Medal, and the Nobel Prize for Physics 2020.