Fall 2024 Compass Lectures

Lecture 1: Testing the standard model with atom interferometry

Speaker: Madeline Bernstein, PhD Candidate in Physics

Date & time: Friday, September 27, 2024, 3:00 – 4:00 PM PDT

Location: 375 Physics North

Talk description: The fine structure constant, denoted by the greek symbol alpha, is a fundamental constant of the Standard Model that represents the strength of electromagnetic interactions. Recent discrepancies in its measured value motivate a more precise measurement. Interferometry is a measurement tool that uses the interference effects of waves to make precise measurements of small quantities. Atom interferometry creates interference with an atomic wavefunction, taking advantage of the particle-wave duality of matter. My experiment uses atom interferometry to precisely measure alpha by measuring the recoil velocity of an atom after absorbing a photon. This is done with an atomic fountain, where atoms are launched into a freefall trajectory, and sent into a quantum superposition of momentum states.

Lecture 2: Working on a NASA gamma-ray telescope mission — a grad student’s perspective

Speaker: Robin Anthony-Petersen, Graduate Student in Physics

Date & time: Friday, October 4, 2024, 3:00 – 4:00 PM PDT

Location: 375 Physics North

Talk description: Propagating past our little blue dot are streams of cosmic gamma-rays. These high energy photons were first theorized in the early 1900’s and were of great scientific interest due to their potential to probe extreme astrophysical environments. Because Earth’s atmosphere blocks most gamma rays, observations must be conducted at high-altitude using either balloons or satellites, meaning it was not until the 1960’s that cosmic gamma-rays were first detected. Since then, gamma-ray astronomy has grown greatly, and detection of MeV gamma-rays is on the forefront of observational astronomy efforts. One mission contributing to this effort is the Compton Spectrometer and Imager (COSI). A new NASA Small Explorer (SMEX) satellite mission scheduled to launch in 2027, COSI will survey the gamma-ray sky from 0.2–5 MeV with great energy and angular resolution. In this talk, I’ll give an overview of COSI and share my perspective on being a grad student and my ongoing battles with GitHub

Lecture 3: Beyond the Standard Model at Future Colliders

Speaker: Kevin Langhoff

Date & time: Friday, October 10, 2024, 3:00 – 4:00 PM PDT

Location: 375 Physics North

Talk description: I will provide a concise overview of the Standard Model of particle physics, highlighting its remarkable successes as well as its key limitations. I will then discuss why addressing these shortcomings demands the existence of physics beyond the Standard Model. Finally, I will delve into the pivotal role that future colliders could play in uncovering deeper insights into the fundamental building blocks of the universe.

Lecture 4: The Search for Habitable Exoplanets

Speaker: Caleb Harada

Date & time: Friday, October 25, 2024, 3:00 – 4:00 PM PDT

Location: 375 Physics North

Talk description: Are we alone in the Universe? How common are habitable planets in our galactic neighborhood? How can we learn about planets in distant star systems anyway? These are some of the questions that have spurred the imagination of scientists and non-scientists alike for millennia. Today, we are at last beginning to seek the answers to these questions using cutting-edge science and technology at the forefront of modern astrophysics. In this talk, I will review how astronomers today detect and measure the properties of extra-solar planets (“exoplanets”) using precise instruments on the ground and in space. Then, I will talk about what makes a planet “habitable” from an astrophysical perspective, and how scientists from around the world are working to measure key indicators of potential habitability on nearby exoplanets. Finally, I will discuss the future landscape of the search for habitable extrasolar worlds, and highlight ongoing work here at Berkeley to investigate the most promising star systems where we may one day find evidence of extraterrestrial life.

Lecture 5: Computing Knot Invariants from Topological Field Theory

Speaker: Elise LePage

Date & time: Friday, November 1, 2024, 3:00 – 4:00 PM PDT

Location: 375 Physics North

Talk description: Usually, one expects new developments in mathematics to lead to breakthroughs in physics. However, it’s often the other way around. I will discuss one such example where new progress in our understanding of topological field theory has allowed us to define and compute new types of invariants of mathematical knots. I’ll start by introducing the physics used and explaining what it means for a theory to be topological. Then I’ll explain what knot invariants are, why they’re important, and how topological field theory naturally computes them.

Lecture 6: Probing Protein Folding with Optical Tweezers

Speaker: Shantanu Kadam

Date & time: Friday, November 22, 2024, 3:00 – 4:00 PM PDT

Location: 375 Physics North

Talk description: The field of biophysics has grown rapidly in the past 30 years, driven by increased crosstalk between physicists and biologists. In 1987, Arthur Ashkin trapped living bacteria with a laser, for which he received the 2018 Nobel Prize in Physics. Optical tweezers utilize the change in momentum that occurs when focused light passes through objects to apply force. The Bustamante lab combines optical tweezing with biochemistry to understand the systems of cellular life. Proteins play a crucial role in cellular pathways, often through structure-mediated interactions. Mechanically probing proteins illuminates folding pathways, thermodynamic stability, and catalytic restrictions. To date, large, highly-stable proteins have been explored. To identify “hidden intermediates” in large proteins and to probe smaller proteins with transient intermediates, we are developing methods for higher spatial and temporal resolution.