### Irreversibility Revisited; my way

As far as we know, the microscopic components of matter obey dynamical laws that are time reversal invariant. In other words, for every initial condition that leads to a certain evolution forward in time, such as a positive current, there corresponds an initial condition that leads to the opposite evolution, again forward in time. How comes that macroscopic objects appear to behave in a clear irreversible fashion, as expressed by the second law of thermodynamics? This question has been in the physicists minds since the early days of statistical physics, and it has received various answers, that often contradict each other. Some would argue that, in fact, the microscopic dynamics are not reversible; others would reply that this
is not necessary for macroscopic irreversibility, hence one should not rely on such microscopic symmetry effects. This leads then to the so called "past hypothesis" and to the need of special initial conditions for our Universe. But, what is irreversibility? How is it connected to entropy? How does it enter a physics reasoning? Which predictions does it lead to? I will summarize the main points of view and I will conclude with personal observations, based on recent developments concerning open systems, and on a principle stated by Feynman, that may require a new perspective on all these issues.

**Friday, 14 June 2019, ore 14:30 — Aula Magna "Tullio Regge" **

### The story of a discovery: how we found the long-sought-after Higgs boson

The search at LEP and at the LHC, and finally the discovery of the Higgs boson at LHC will be discussed. The measurements and the future prospects will be presented. The scientific part will be enriched with some anecdotes.

**Wednesday, 29 May 2019, ore 14:30 — Aula Magna "Tullio Regge" **

### Gravitational waves: listening to the whispers of the Universe

In February 2016, for the first time Gravitational Waves detection has been announced by the LIGO-Virgo collaboration. In the following years, during the first and second Observing Runs of the Advanced Gravitational-Wave detectors, 11 signals in total were observed. Due to their week
amplitude, Gravitational Waves are expected to produce a very small effect on free-falling masses, which undergo a displacement of the order of 10^(-18) m. For the time being, interferometric detectors are the most sensitive instruments to measure such relative distance change, which is
translated into phase variation of the laser field. Detecting such a feeble effect is a tough challenge against the noise sources, which overcome by several orders of magnitude the strength of the Gravitational Wave effect.
In this Colloquium, I will talk you through the complexity of the experimental work underling the tuning of this instrument. Starting from the working principle of the detector, we will go through the fundamental noise sources which limit the interferometer sensitivity, the challenges of installation,
commissioning, tuning and calibration faced by Virgo, a 3 kilometer-long arms interferometer situated near Pisa, until the achievement of the sensitivity milestone, which allowed the Virgo detector to start the third joint Observation run together with the two Advanced LIGO interferometers.

**Friday, 24 May 2019, ore 14:30 — Sala Wataghin **

### Pulling Yourself by your Bootstraps in Quantum Field Theory

Quantum field theory (QFT) is the universal language of theoretical physics, underlying the Standard Model of elementary particles, the physics of the early Universe and a host of condensed matter phenomena such as phase transitions and superconductivity. A great achievement of 20th-century physics was the understanding of weakly coupled quantum field theories where interactions can be treated as small perturbations of otherwise freely moving particles. Critical challenges for the 21st century include solving the problem of strong coupling and mapping the whole space of consistent QFTs.
In this lecture, I will overview the bootstrap approach, the idea that theory space can be determined from the general principles of symmetry and quantum mechanics. This strategy provides a new unifying language for QFT and has allowed researchers to make predictions for physical observables even in strongly coupled theories. I will illustrate the general framework in a few examples, ranging from the concrete (boiling water) to the abstract (supersymmetric theories in various spacetime dimensions).

**Friday, 17 May 2019, ore 14:30 — Sala Wataghin **

### Standard Model or Standard Theory? - The potential of precision in the next decade

The impressive extension of successful tests of the Standard Model of elementary particles suggests to promote it to a/the Standard Theory. After arguing why this may be premature, I discuss the potential of precision measurements in the next decade or so to search for possible Beyond the Standard Model effects, crucial to try to answer the question of the Title.

**Friday, 3 May 2019, ore 14:30 — Aula Magna "Tullio Regge" **

### Particle Scattering and Number Theory

From the softest of interactions of a magnetic field with an electron, to the most violent collisions at the Large Hadron Collider, precision quantum field theory produces numbers and functions with interesting number-theoretic properties. In many examples a co-action principle holds, an invariance under a ?cosmic? Galois group. I will provide several arenas in which this principle can be seen at work, including perhaps the richest set of theoretical data, scattering amplitudes in planar N=4 super-Yang-Mills theory.

**Tuesday, 16 April 2019, ore 14:30 — Aula Magna "Tullio Regge" **

### From Bell's inequality to quantum computers: the long journey of Alice and Bob

It will be 55 years in a few months, since the fundamental paper by John Bell ("On the Einstein Podolsky Rosen Paradox", Physics. 1: 195?200) was published. It is fair to say that the consequences of that extraordinary work went way beyond imagination, revolutionizing our understanding of nature, and providing the necessary momentum for moving towards a world where "quantum" is the common adjective for communication and computation, for logics and biology, for teleportation and the internet.
In this seminar we will first meet the players of the quantum world (qubits, quantum gates, and measuring apparatuses), and see how they appear from the backstage of quantum mechanics.
We will then introduce the true lead of the scene, namely "entanglement", and show why and how it really makes the difference between quantum and classical. The second part of the seminar will see us following the journey that took the most famous qubit-pair, Alice and Bob, from the quantum parallelism of the Deutsch algorithm and the incredible speed-up of the quantum Fourier transform, to the experiment that realized quantum teleportation through the 143km between Las Palmas and Tenerife and the quantum computers which are today up and running in several laboratories. We will finally end our excursion with a view into the future of quantum biology and quantum learning machine.

**Friday, 22 March 2019, ore 14:30 — Aula Magna "Tullio Regge" **

### How statistics of driven non-equilibrium systems appears from the theory of sample space reducing processes - all of it - from Gauss to Zipf

Sample space reducing (SSR) processes are simple path-dependent processes that offer an easy analytical understanding of the origin and ubiquity of power-laws in countless driven complex systems out of equilibrium. SSR processes exhibit generic power-laws - Zipf's law in particular. We show that SSR processes exhibit a much wider range of statistical diversity. Assuming that driving in a system is not uniformly strong within a system or across its life-span, but depends on the current state the system is in, we demonstrate that practically any distribution function can be naturally derived from SSR processes: Slow driving gives Zipf's law, constant driving leads to exact power-laws. More complicated driving processes yield exponential or Gamma distributions, normal distribution, Weibull, Gompertz, and Tsallis-Pareto distributions. We shortly discuss the areas of application of SRR processes that range from fragmentation processes, language formation, cascading processes,search processes, and multiplicative processes.

**Friday, 15 March 2019, ore 11:30 — Aula Magna "Tullio Regge" **

### New approaches to galaxy clustering

The large-scale clustering of galaxies contains a wealth of information on the geometry and expansion history of the universe, on gravity, and on the initial conditions. In order to extract this information, we need to deal with the complex formation process of galaxies. As a result, current observational constraints are largely based only on the robust BAO feature. However, thanks to significant advances in our theoretical understanding of galaxy clustering, we now have a well-defined approach for absorbing all the complicated, incompletely understood physics of galaxy formation into a set of free parameters (the bias parameters and stochastic amplitudes), which opens up considerable additional constraining power. The next challenge to tackle then is how best to connect this theory with data, as delivered by ongoing and future surveys such as BOSS, DESI, and Euclid. In my talk, I will review these developments, and discuss the prospects galaxy clustering as a robust probe of cosmology in the coming decade.

**Friday, 8 March 2019, ore 14:30 — Sala Wataghin **

### The Standard Model and Experiment

During the second half of the twentieth century theorists made an enormous progress in understanding the nature of matter's elementary constituents and the interactions among them. This progress led to the construction of
an elaborate edifice, known as "The Standard Model". Its basic ingredient is an abstract geometrical concept of symmetry which we will exemplify in this talk. The comparison of the Standard Model predictions with experiment shows a spectacular agreement which we will briefly present. We will also signal a few cases of slight disagreement and discuss their potential significance.

**Friday, 8 February 2019, ore 14:30 — Aula Magna "Tullio Regge" **