Academic

Name	Primary Category	Discipline/Position	Phone	Office
Kramer Eric David	Post-Docs	High Energy Physics		Ross -2 1D
Krief Menahem	Graduate Students	Nuclear Hadronic and Few-Body Physics		Popick Bldg.
Kuflik Eric	Faculty	High Energy Physics		Ross -2 1A
Laikhtman Boris	Emeriti	Condensed Matter Physics	02 6585 676	Danciger B 100
Lapiner Sharon	Graduate Students	Astrophysics and Relativity
Leidershneider Elly	Graduate Students	Astrophysics and Relativity
Leviatan Amiram	Faculty	Nuclear Hadronic and Few-Body Physics	02 6585 136	Kaplun 206
Levin Ido	Graduate Students
Levi Rotem	Graduate Students	Astrophysics and Relativity
Lichtenstadt Itamar	Emeriti	Astrophysics and Relativity	02 6584 491	Popick 107

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Upcoming Events

Yesterday

Astrolunch: Cecilia Chirenti
- Start time: 04:00pm
- End date: Tuesday, December 3rd
- End time: 05:00pm
- Speaker: Prof. Cecilia Chirenti (Federal University of ABC, Santo Andre, Brazil; Department of Astronomy, University of Maryland, USA)Title: Quasi-periodic oscillations in short gamma-ray bursts and implications for neutron starsAbstract:Short gamma ray bursts (GRBs) have already been associated with binary neutron star mergers, which are also sources of gravitational waves. Numerical relativity simulations indicate that the merger can form a short-lived hypermassive neutron star (which could produce a millisecond magnetar), lasting for tens to hundreds of milliseconds before gravitational collapse forms a black hole. This neutron star remnant is expected to emit gravitational waves (GWs) with kHz frequencies that will be detectable by third generation ground-based GW detectors in the 2030s. Recently, kHz quasiperiodic oscillations were discovered in GRBs 910711 and 931101B, providing evidence for a hypermassive neutron star stage in these events. When analyzed together with new quasi-universal relations obtained from numerical relativity simulations, these detections provide a novel method to constrain the equation of state of the dense matter in neutron star cores.Zoom link:https://huji.zoom.us/j/83438422733?pwd=bO4fe7y4WgZ5OWdFjaUxulnbjurow1.1Meeting ID: 834 3842 2733Passcode: 294941 Contact: Dima Ofengeim
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Monday, December 9th

Physics Colloquium : "Criticality, universality and Grokking in Neural Networks"
- Start time: 12:00pm
- End date: Monday, December 9th
- End time: 01:30pm
- Lecturer: Yohai Bar-Sinai, Tel Aviv UniversityAbstract:The empirical success of neural models far surpasses their theoretical understanding, and explaining their inner workings is important both as a fundamental scientific question and for practical reasons. In this talk I’ll review some “big questions” in the field, and the prospects of applying physics-inspired methodologies to tackle them. We will focus on an intriguing phenomenon named Grokking, where a neural model learns to generalize long after it has completely fit the training data. This transition often occurs abruptly and has been observed across a range of synthetic and realistic scenarios. By investigating Grokking in simplified models—such as linear or near-linear systems—we leverage tools from statistical mechanics, random matrix theory, and optimization to gain insights. We claim that Grokking is a near-critical phenomenon, appearing near singularities in the "thermodynamic limit" (in some proper sense) of training dynamics. Specifically, delayed generalization stems from “critical slowing down”, a generic feature of systems near phase transitions, that induces slow dynamical time scales near almost-stable fixed points. This perspective enables us to derive concrete scaling predictions that are applicable even in more complex settings, owing to the universal nature of critical phenomena.
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Tuesday, December 10th

Quantum Physics Seminar: ""
- Start time: 12:00pm
- End date: Tuesday, December 10th
- End time: 01:30pm
- Lecturer: Hagai Diamandi (Applicant) Abstract:
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astrolunch: Fabio Pacucci
- Start time: 05:00pm
- End date: Tuesday, December 10th
- End time: 06:00pm
- Title: JWST's Little Red Dots: Masters of Disguise in the High-Redshift Universe This talk will explore the exciting journey to probe several populations of black holes, spanning from the distant to the local Universe. I will focus primarily on the "little red dots" (LRDs), a newly discovered and puzzling population of compact red sources at redshift z > 4, identified by JWST. These objects challenge our current astrophysical models in several ways. First, I will discuss the detection of overmassive black holes relative to the stellar mass of their host galaxies. Second, I will address the X-ray weakness problem, where these sources remain undetected in deep X-ray surveys. I will use advanced GRRMHD simulations to show how mildly super-Eddington accretion onto slowly spinning black holes can resolve this issue. Third, I will explore the extremely high stellar densities at the cores of these objects and their potential for triggering runaway stellar collisions. Throughout the talk, I will also discuss how the LRDs represent a perfect bridge to study other populations of black holes, with a focus on the role of future observatories such as HWO and AXIS. These include the search for black hole seeds at redshifts z = 20-30 and the detection of quiescent black holes in the local Universe.Bio: Fabio Pacucci is a Clay and BHI Fellow at the Center for Astrophysics. He obtained his PhD in Physics from the Scuola Normale Superiore in Pisa, Italy.He is an expert in the theory and observations of high-z black holes and is part of several large JWST programs.He is also involved in planning next-generation observatories, such as NASA's AXIS in the X-ray, which was just selected for Phase A, and HWO in the UV, optical, and infrared, which will be NASA's next flagship mission.contact: Zhaozhou
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