Conceptual Issues in Fundamental Physics

9 juin 2017, 08:00 → 13 juin 2017, 18:00 Europe/Paris

LPSC Grenoble (June 9th) & LAPTh Annecy (June 13th)

Aurélien Barrau (LPSC), Cecile Renault (CNRS), Luca Fabbri, Marie-Hélène Genest (LPSC Grenoble), Pierre Salati

These two days, one at LPSC and one at LAPTh, will be devoted to discussing some conceptual issues in fundamental physics, with the aim of gaining a global overview of the key concepts at play, their implications and possible interpretations. All curious physicists (students and researchers, experimentalists and theorists) are cordially invited! The presentations by invited speakers will be followed by question / discussion sessions. You can find abstracts on the timetable.

• June 9th (LPSC Grenoble)
  • 10:30 Francesca Vidotto (IMAPP Nijmegen) - No Time No Problem
  • 14:00 Marco Guagnelli (INFN Pavia) - Do Virtual Particles Really Exist?
• June 13th (LAPTh Annecy)
  • 10:30 Philippe Brax (IPhT CEA Saclay) - What is the Problem With the Cosmological Constant?
  • 14:00 Alexia Auffèves (Institut NÉEL Grenoble) - A Physically Realist Ontology for Quantum Mechanics

There is no fee, but registration is mandatory (before June 1st) for the free lunch.

                 

The logo is an artwork by the artist Red called  "Distoriyan".

 

 

Poster Poster_CIFP2017.pdf

vendredi 9 juin

09:45 → 10:30 Café

10:30 → 10:35 Introduction

Orateur: Dr Luca Fabbri (-)

Transparents CIFP.pdf

10:35 → 12:35 No Time No Problem

Exactly half of a century ago Wheeler and de Witt wrote the iconic first equation of quantum gravity. Puzzlingly, the equation does not feature any time variable. Where is time gone? How can we describe the evolution of physical systems in absence of a preferred time variable? How can time emerge in the passage from the quantum to the classical world? I will review the problem, the strategies adopted to overcome it and some insights from ongoing research in quantum gravity.

Orateur: Francesca Vidotto (IMAPP Nijmegen)

Transparents Vidotto-Grenoble-2017.pdf

14:00 → 16:00 Do Virtual Particles Really Exist?

When physicists tried to unify Quantum Mechanics with Relativity, it soon became clear that the resulting theory could not conceivably be a single particle one. Creation and destruction of particles had to be taken into account. The theory we end up with is a Relativistic Quantum Field Theory: particles are just quanta of the respective fields. The outstanding success of Feynman's Path Integral formalism brought into some kind of "physical reality" the so called "virtual particles". Virtual particles are not observable asymptotic states, but can exist as long as they don't violate Heisenberg uncertainty principle. Their existence is used, didactically, to explain a lot of phenomena; for example, the running of the electron charge, or coupling constant, with energy, via the screening obtained by vacuum polarization of the cloud of e+ e- virtual couples that surround the "true" electron. I'd like to discuss what happens to this kind of reasoning when a QFT is treated in a non-perturbative way.

Orateur: Marco Guagnelli (INFN Pavia)

Transparents Marco_Guagnelli_CIFP.pdf

mardi 13 juin

10:30 → 10:35 Introduction

Orateur: Dr Luca Fabbri (-)

Transparents CIFP.pdf

10:35 → 12:35 What is the Problem With the Cosmological Constant?

I will discuss the different aspects of the cosmological constant problem, both theoretically from the point of field theory and phenomenologically with an increasing number of observations suggesting that some form of dark energy is required. Several attempts to address this issue will be reviewed, although none has proved to be successful so far.

Orateur: Philippe Brax (IPhT CEA Saclay)

Transparents Conceptual_Issues_Philippe_Brax.pdf

14:00 → 16:00 A Physically Realist Ontology for Quantum Mechanics

I will present a possible way to make usual quantum mechanics fully compatible with physical realism, defined as the statement that the goal of physics is to study entities of the natural world, existing independently from any particular observer’s perception, and obeying universal and intelligible rules. Rather than elaborating on the quantum formalism itself, a new quantum ontology is proposed, where physical properties are attributed jointly to the system, and to the context in which it is embedded. In combination with a quantization principle, this non-classical definition of physical reality sheds new light on counter-intuitive features of quantum mechanics such as the origin of probabilities, non-locality, and the quantum-classical boundary.

Orateur: Alexia Auffèves (Institut NÉEL Grenoble)

Transparents Conceptual_Issues_Alexia_Auffeves.pptx