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Physics Colloquium Series


Physics Colloquium presents a venue for the latest developments in all branches of physics in a way accessible to non-expert physicists. The monthly Physics Colloquia take place on selected Wednesdays at 4:30 pm in the Conference Hall of the main Farmanieh building, with an announcement circulated in advance. Please forward your suggestions for potential Colloquium speakers to a.naji(at)ipm.ir. To subscribe to the Colloquium mailing list, please send an email with the subject line "subscribe me to physics colloquium" to physoffice(at)theory.ipm.ac.ir. 
 

Wed Jun 29, 2022 (1401/4/8)

       

Jun 29
1401/4/8

18:00
 

Disease Ecology from Perspectives of Physics

Abstract:Here I will review my recent works [1-14] on modeling interacting contagious dynamics, for example coupled SIR or SIS dynamics, in mean field approximations and also on different random generated or empirical complex networks. I show and discuss how our recent results have been improving our understanding and prediction of epidemic dynamics and disease ecology while raising new questions and challenges in physics of critical phenomena. Also I will briefly discuss SARS-COV-2 from the perspective of disease ecology and present my recent studies on "behavioral responses to the COVID-19 spread"; which focus on the analysis and modelling of empirical data including testing strategies, air traffic, urban mobility, inequality (socio-economic classes), news spread, etc. in Iran or USA or globally.
Lecturer(s): Fakhteh Ghanbarnejad
From : Sharif University of Technology
Research Group: Physics Colloquium
More Info. : Link

Wed May 25, 2022 (1401/3/4)

       

May 25
1401/3/4

18:00
 

How living matter self-organizes while breaking action-reaction symmetry

Abstract:There are many ways to study life, and one that is particularly appealing to physicists is regarding it as self-organized active soft matter that is away from equilibrium ``just the right way. In this Colloquium, I will discuss this notion, and provide a number of examples of how we can begin to put together simple systems - from basic ingredients that we fully understand - that would exhibit the kind of active behaviour we find in living systems. In particular, I will discuss the general class of chemical activity both as the source of non-equilibrium drive and the underlying mechanism for self-organization. Cells and microorganisms produce and consume all sorts of chemicals, from nutrients to signalling molecules. The same happens at the nanoscale inside cells themselves, where enzymes catalyze the production and consumption of the chemicals needed for life. In this colloquium, I will discuss a generic mechanism by which such chemically-active particles, be it cells or enzymes or engineered synthetic colloids, can "sense" each other and ultimately self-organize in a multitude of ways. A peculiarity of these chemical-mediated interactions is that they break action-reaction symmetry: for example, one particle may be repelled from a second particle, which is in turn attracted to the first one, so that it ends up "chasing" it. Such chasing interactions allow for the formation of large clusters of particles that "swim" autonomously. Regarding enzymes, we find that they can spontaneously aggregate into clusters with precisely the right composition, so that the product of one enzyme is passed on, without lack or excess, to the next enzyme in the metabolic cascade. Finally, I will discuss how breaking the action-reaction symmetry can allow a system described by two scalar fields to exhibit spontaneous breaking of time translation, time-reversal, space translation, and polar symmetries.
Lecturer(s): Ramin Golestanian
From : Max Planck Institute for Dynamics and Self-Organization & Oxford University
Research Group: Physics Colloquium
More Info. : Link

Wed Apr 06, 2022 (1401/1/17)

       

Apr 06
1401/1/17

18:00
 

Uncovering Energetic Processes in the Interstellar/Intergalactic Medium with the Square Kilometre Array

Abstract:Investigating the physics and energetic of the medium where galactic structures, on various scales, are formed is the most fundamental step to understand the formation and evolution of galaxies. Modern galaxy evolution models suggest gas accretion from the intergalactic medium (IGM) or from cosmic filaments as a mechanism to maintain star formation and active galactic nucleus (AGN). Through gas heating and/or gas removal, these models also propose supernova feedback and AGN feedback as mechanisms to quench massive star formation. Observational studies, however, have not reached to a conclusive result showing that feedback can, in some cases, trigger star formation, leaving the issue as an open challenge. It seems that some basic concepts about the formation of structures in the interstellar medium (ISM) and the IGM are missed: What are physical parameters/agents governing the structure formation on various scales? How does the ISM/IGM energy balance change over cosmic time? The advent of the square kilometre array (SKA) and its instrumental capabilities tracing the most energetic ISM components has opened a new window shedding light on the issue. The SKA's sensitive radio continuum observations will trace high-energy particles and magnetic fields not only in star forming regions and AGNs, but also in more quiescent regions in molecular clouds and diffuse IGM, enabling us to study the role of magnetic fields/cosmic rays in structure formation. Sensitive radio continuum observations on large scales may also bring constrains on the entity of dark matter mapped by the Hubble Space Telescope (HST) and Dark Energy Camera (DECam).
Lecturer(s): Fatemeh Tabatabaei
From : IPM, School of Astronomy
Research Group: Physics Colloquium
More Info. : Link

Wed Mar 02, 2022 (1400/12/11)

       

Mar 02
1400/12/11

18:00
 

Dance of Cause and Effect: Fluctuation Induced Reduction of Dissipation in Classical Fluids

Abstract:About seventy years ago, G I Taylor noticed that the tails of two closely swimming spermatozoa, oscillate in a synchronized fashion as if both of them are controlled from one regulating center. The two sperms, on the other hand, has no mean of communication, but the viscous fluid in which they are swimming. To address the why question, behind the observation, he suggested the minimization of total dissipation in the viscous medium. Sixty years later, Taylors original idea was put to more detailed analytical investigations; non-intuitively, it failed to attribute the observed synchronization to the expected reduction of dissipation. We begin with a very different problem: (a) The motion of two passively trapped beads, which interact through hydrodynamic interactions, and face a driven flow. Both theoretically and experimentally we observe that they almost follow the very motion they would have, if they were to swim on their own in the opposite direction of the driven flow. Calling the phenomenon, the reverse dance, we successfully attribute it to the reduction of the total dissipation. We then (b) extend the minimalistic approach, to two sets of beads; each supposed to mimic the tail of one spermatozoon. Facing a driven flow, on top of their intrinsic oscillation, this is a minimalistic model to verify Taylors idea. The question is, does this simple model lead us to synchronization as well as reduction of fluids dissipation? And if so, can it explain why Taylors original model failed to correctly attribute synchronization with reduction of dissipation?
Lecturer(s): Seyyed Nader Rasuli
From : University of Guilan & School of Physics, IPM
Research Group: Physics Colloquium
More Info. : Link

Wed Feb 02, 2022 (1400/11/13)

       

Feb 02
1400/11/13

18:19
 

Einstein vs Einstein: The Great War

Abstract:Within the span of seven months in the midst of the Great War, Albert Einstein published two seminal papers, on "Quantum Emission and Absorption" and "Field Equations of Gravitation", that laid the foundations of modern physics. Our century-long odyssey starts here, taking us through the rise of holography, fuzzballs, firewalls, quantum chaos, and gravitational wave astronomy. However, in the end, it will land us back within those fateful seven months, where Einstein's July 1916 "Strahlungs-Emission und -Absorption nach der Quantentheorie" may prove to be the ultimate undoing of his December 1915 "Die Feldgleichungen der Gravitation". I will lay down the theoretical and observational arguments on both sides of (the latest battle) in Einstein's Great War.
Lecturer(s): Niayesh Afshordi
From : Department of Physics and Astronomy, University of Waterloo
Research Group: Physics Colloquium
More Info. : Link

Wed Jan 05, 2022 (1400/10/15)

       

Jan 05
1400/10/15

18:00
 

On Progress in Scientific Theories

Abstract:Thomas Kuhn's "theory of scientific revolutions" describes evolution in sciences from a socio-historic viewpoint, wherein paradigm shift happens as a result of a scientific revolution. According to this theory paradigm shifts are not oriented, there is no progress in scientific paradigms. In this seminar, I critically review Thomas Kuhn's theory and introduce the notion of "hyper-theory" instead of paradigm. We then discuss that not only there are meaningful ratings for scientific models, but there is also a notion of progress in theories and hyper-theories. I present and state "model of progression scientific theories" instead of Kuhn's theory.
Lecturer(s): M. M. Sheikh-Jabbari
From : IPM, School of Physics
Research Group: Physics Colloquium
More Info. : Video Link

Wed Feb 05, 2020 (1398/11/16)

       

Feb 05
1398/11/16

16:00
 

Fundamental Successes and Challenges of the Contemporary Physics
Abstract

Lecturer(s): Mehdi Golshani
From : Sharif University of Technology & IPM
Research Group: Physics Colloquium
Farmanieh Conference Hall

Wed Dec 11, 2019 (1398/9/20)

       

Dec 11
1398/9/20

16:00
 

Primordial Universe and Cosmic Inflation
Abstract
Note
Audio File

Lecturer(s): Hassan Firouzjahi
From : IPM, School of Astronomy
Research Group: Physics Colloquium
Farmanieh Conference Hall

Wed Nov 20, 2019 (1398/8/29)

       

Nov 20
1398/8/29

16:00
 

The Higgs Boson program at the LHC and future colliders
Abstract

Lecturer(s): Mojtaba Mohammadi Najafabadi
From : IPM, School of Particles and Accelerators
Research Group: Physics Colloquium
Farmanieh Conference Hall

Wed Mar 06, 2019 (1397/12/15)

       

Mar 06
1397/12/15

16:30
 

"Landau and Ginzburg" remove tensions between "Planck" and "Hubble and Lyman"
Abstract

Lecturer(s): Nima Khosravi
From : Shahid Beheshti Univ. & IPM
Research Group: Physics Colloquium
Farmanieh Seminar Room
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