Experimental Studies of Black Holes: Status & Prospects

More than a century ago, Albert Einstein presented his general theory of gravitation. One of the predictions of this theory is that not only particles and objects with mass, but also the quanta of light, photons, are tied to the curvature of space-time, and thus to gravity. There must be a critical mass density, above which photons cannot escape. These are black holes. It took fifty years before possible candidate objects were identified by observational astronomy. Another fifty years have passed, until we finally can present detailed and credible experimental evidence that black holes of 10 to 10¹⁰ times the mass of the Sun exist in the Universe. Three very different experimental techniques have enabled these critical experimental breakthroughs. It has become possible to investigate the space-time structure in the vicinity of the event horizons of black holes. I will summarize these interferometric techniques, and discuss the spectacular recent improvements achieved with all three techniques. In conclusion, I will sketch where the path of exploration and inquiry may lead to in the next decades.

Reinhard Genzel, born 1952 in Bad Homburg v. d. H., Germany, is one of the Directors of Max Planck Institute for Extraterrestrial Physics, Professor in the Graduate School of the University of California, Berkeley and an Honorary Professor at the Ludwig Maximilian University, Munich. He is a Scientific Member of the Max Planck Society and a member of the US National Academy of Sciences. His research interests include astrophysics of galactic nuclei, star formation, kinematics and cosmic evolution of galaxies, massive black holes and experimental infrared, submillimeter and millimeter astronomy. He has received numerous honours and awards, including the Shaw Prize of The Shaw Prize Foundation and the Crafoord Prize in Astronomy. In 2020, he received the Nobel Prize in Physics, jointly with Andrea Ghez, for the discovery of a supermassive compact object at the centre of our galaxy.

https://science.umd.edu/events/genzel.html

Relativistic optics and laser-driven particle accelerators

The remarkable increase in peak laser intensity over the past 30+ years –over 6 orders of magnitude--has spurred new and exciting advances in laser-driven sources of relativistic charged particles and light, along with the new field of indestructible plasma optics. I will start with our recent results demonstrating acceleration of electrons up to 10 GeV in just 30 cm—a distance 5,000 times smaller than required using conventional technology, and then work backward to highlight the physics building blocks that made such a result possible.

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Challenges and Opportunities in Communicating STEM

This talk aims to explore twin universal concerns in communicating scientific work, for any audience. For one, we will describe and demonstrate elements of craft: distilled, actionable lessons from professional writers translated and applied to the unique challenges we face in relaying complex technical projects. These elements include familiar obstacles like jargon but also less familiar opportunities like basic narrative tension. For another, we will explore calibration: research from cognitive science and human brain evolution can serve us well in considering our audiences with savvy compassion. In sum, the talk seeks to improve the clarity, impact, and persuasive power of our work, with hopes of benefiting scientists and engineers at any stage of their careers.

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The Quantum Reform of the Modern Metric System:  Mass becomes quantum, and electrical measurements become honest

The modern metric system, officially known as the International System of Units (SI), has recently undergone its most revolutionary change since the inception of the metric system at the time of the French revolution.  The kilogram, ampere, kelvin, and mole all have new definitions, based on fixing the values of fundamental constants of nature.  Famously, the reform eliminates the artifact International Prototype Kilogram as the foundation of the unit of mass.  This lecture will explain why this was necessary and how it was accomplished.  Less famously, the century-old practice of having two separate unit systems for electrical metrology —“legal” and “scientific”— has disappeared with the reformed SI.    

https://ireap.umd.edu/events/paint-branch-distinguished-lecture-applied-physics-2024

Asymptomatic: The Silent Spread of COVID-19 and the Future of Pandemics

This talk explores an idea and its consequences. The first part leverages dynamical principles and public health data to explain how COVID-19's ability to silently spread between individuals often without causing illness is precisely what made it catastrophic for society as a whole. The second part looks ahead and identifies model-informed public health approaches that can effectively reduce asymptomatic transmission so as to prevent and control future pandemics.

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Neutrino Astronomy: Viewing the High Energy Sky Through the South Pole Glacial Ice

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