Lectures

October 8 @ 14:15 - The many faces of neutron stars

Speaker: Manuel Linares, Department of Physics, NTNU

Place: D5-175

Abstract: We know more than three thousand neutron stars in our Galaxy because we see them as "pulsars", and many more are hidden. Neutron stars show many faces throughout their lives, displaying a wide range of phenomena powered by rotational, gravitational, magnetic and nuclear energy. I will explain how neutron stars are born, how they live and die, and how they can be resurrected. I will also review recent progress in the hunt for super-massive neutron stars, with more than 2 times the mass of the Sun. These give new constraints on the properties of ultradense matter as well as on the possible outcomes of double neutron star mergers.

October 15 @ 14:15 - Title: Magnetic field matters in spinal cord MRI

Speaker: Johanna Vannesjo, Department of Physics, NTNU

Place: D5-175

Abstract: Signal encoding in MRI is crucially dependent on a strong background magnetic field that is temporally stable and spatially homogenous, upon which time-varying, spatially linear, "gradient" fields are added for spatial encoding. Several factors, however, perturb the encoding magnetic fields, giving rise to artefacts that can obscure image features and bias quantitation. Imaging of the spinal cord is particularly affected by both static and dynamic magnetic field imperfections owing to the anatomical and physiological environment of the spinal cord. The issue of field fidelity is further exacerbated on ultra-high field (7 Tesla) MR systems, while these at the same time can yield superior image resolutions compared to regular clinical systems. In this talk, I will outline common factors compromising the encoding magnetic fields, show examples of their relevance, and discuss novel approaches to overcoming these challenges, with a focus on spinal cord imaging at 7T.

November 12 @ 14:15 - Multimessenger astronomy with high-energy neutrinos

Speaker: Foteini Oikonomou, Department of Physics, NTNU

Place: D5-175

Abstract: The recent discovery of high-energy astrophysical neutrinos has opened a new window to the Universe. Identifying the sources of these neutrinos is the main focus of the emerging field of neutrino astronomy. Combining neutrino data and electromagnetic measurements in a multi-messenger approach may lead us to the sources of the neutrinos and help to solve the long-standing big question of the origin of high-energy cosmic rays. A leading candidate source population is active galaxies, which host accreting supermassive black holes and relativistic jets. In this talk I will review the current status of  the field and what we know about the possible role of jetted AGN as sources of high-energy neutrinos.

November 26 @ 14:15 - The Nobel Prize in Physics 2021 (Part I: G. Parisi)

Speaker: Luca Leuzzi, CNR-NANOTEC and Università Sapienza, Italy

Place: Zoom meeting

Title: Replica Symmetry Breaking theory for complex disordered systems: from spin-glasses to random lasers

Abstract: After a very concise account of the many motivations for this year Nobel prize in physics for “FOR GROUNDBREAKING CONTRIBUTIONS TO OUR UNDERSTANDING OF COMPLEX PHYSICAL SYSTEMS” to Syukuro Manabe, Klaus Hasselmann and Giorgio Parisi, we will focus on the theory for complex disordered systems known as Replica Symmetry Breaking (RSB) theory.
This is the approach that allows to understand and predict the behaviors of systems displaying a phase characterized by infinitely many states. Not just two, as in a magnet, but an infinite number.

We will make a short historical survey on the theory of spin-glasses, beginning with Edwards and Anderson in 1975 and having a fundamental breakthrough with Parisi in 1979, trying to show how new concepts and mathematical tools were introduced.
We will show how, apart from spin-glasses, different complex phenomena can be described by different kinds of RSB.

We will eventually dedicate the final part of the talk to the quest for the experimental demonstration of the theory, that we formalized and performed in the framework of random lasers (2015).

The measure of the Parisi order parameter is a complicated problem because large disordered systems take a very long time to thermalize and because microscopic spin configurations have to be measured to evaluate overlap values. We tackle the problem in which the role of spins is played by light modes, established and coupled in an optically random medium because of multiple light scattering. In presence of external power pumping this model reproduces the behavior of a particular kind of so-called random lasers. We termed them glassy random lasers.
The statistical mechanical theory of the stationary lasing regime, a theory of multimode light amplification in random media, is nothing else than a spin-glass theory, displaying a variety of RSB regimes as the pumping increases.

December 3 @ 14:15 - The Nobel Prize in Physics 2021 (Part II: S. Manabe & K. Hasselmann)

Speaker: Gabriele C. Hegerl, University of Edinburgh, UK

Place:  Zoom meeting

Title: Explaining climate variability and detecting fingerprints for the human Influence on Climate

Abstract: This presentation gives a brief introduction to the work of the two recent nobel laureates, who laid the foundation for modelling climate and predicting and detecting changes in climate caused by greenhouse gas increases in the atmosphere caused by burning of fossil fuels. Suki Manabe laid the foundation for climate modelling, and Klaus Hasselmann predicted climate variability on all timescales due to the ocean response to short-term weather noise. Klaus also proposed a method to detect the climate response to greenhouse gases in observed data, and the speaker has implemented that method under his supervision in the 1990s, and as a result we were some of the first to detect climate change and the first to propose a method to attribute it to causes. I will discuss this method and some recent follow on work on this.

December 10 @ 14:15 - Women’s Pathways in the Sciences

Speaker: Gerhard Sonnert, Harvard University, USA

Place: Zoom meeting

Abstract: Even though progress has been made in the United States over the last half-century in women’s representation in the sciences, gender parity has not yet been achieved, while substantial differences persist between scientific disciplines. In this talk, I will focus on three topics. First, I will address the evolution of astrophysics out of astronomy in the late 19th and early 20th centuries as a case example to discuss how scientific and technological advances were intertwined with the early entry of women into the field. Second, I will draw lessons from contemporary research on the careers of women in the sciences. Finally, I will present empirical data from large survey studies in the United States about young persons’ interest in pursuing careers in the sciences, about the factors that support such an interest, and about gender differences in the efficacy of these factors.