Thursdays, 4:00-5:00 pm
For more information, contact Katsushi Arisaka.
Thermal Infrared and Cosmological Observations from Space
Edward (Ned) Wright
University of California, Los Angeles
Abstract: Thermal IR spans the range of wavelengths from 2.3 to 300 microns. In this broad range, radiation from room temperature optics overwhelms the radiation from the night sky, producing a much as 26 million photons/second of telescope background at 10 microns in a diffraction-limited beam. Goingtospaceallowscoldtelescopetoreducethisbya factor of 3 million. Objects that radiate primarily in the IR include very high redshift galaxies, cold brown dwarfs or free floating planets planets, and very dusty protostars: "the old, the cold and the dusty". I will discuss COBE, WMAP, the Spitzer Space Telescope and WISE which are already in space. Finally, I will discuss NEO Surveyor, a Planetary Defense Mission to locate potentially hazardous asteroids which is scheduled for 2027.
To Ignition and Beyond!
Denise Hinkel
Lawrence Livermore National Laboratory
Abstract: Sixty years in the making – over 6 decades of scientific and technology development culminated in achieving ignition in the laboratory using the approach of inertial confinement fusion (ICF). From the time (~ 30 years ago) that Lawrence Livermore National Laboratory undertook key decision zero for construction of the National Ignition Facility (NIF), with the end goal of ignition, to present has been an “E-ticket ride”, meaning it has been very exciting! This journey was filled with scientific discovery, phenomenal technological advances, and teaming of simulation and data to drive advances in scientific understanding, in yield, and in target gain. The fundamentals of inertial confinement fusion will be presented, as will an overview of the approach. A discussion of predictive capability will highlight why this work is a scientific grand challenge, and what the next steps are for the national ICF program.
Developing New Windows Into the Secret Lives of Cells
Eric Betzig
University of California, Berkeley
2014 Nobel Prize in Chemistry
Abstract: The hallmark of life is that it is animate. To gain a better understanding of how inanimate molecules assemble to create animate life, it is necessary to image the dynamics of living organisms noninvasively at high resolution in both space and time. Beginning in the 1980's, the widespread availability of computers, lasers, sensitive detectors, and fluorescence labeling techniques has allowed physicists and engineers to develop new microscopes with the ability to understand the findings of genetics and biochemistry in the context of spatially complex and dynamic living systems. I will discuss the role of my lab in this developing story, and show how an increasingly detailed look at life has increasingly revealed an intricate and beautiful world.
Membranes, RNA World and the Origin of Life
Robijn Bruinsma
University of California, Los Angeles
Abstract: Molecular self-assembly and self-replication are central in attempts to reproduce the earliest biological systems in a laboratory setting. The colloquium will discuss these concepts and then focus on the proto-cells that were developed in the laboratory of Nobel laureate Jack Szostak. Interplay between the physics of membranes and the self-replication of nucleic acids produces new physical phenomena that allow the proto-cells to assemble, grow, divide, and acquire increased complexity. A second focus of the colloquium will be on the question how proto-cells can capture free energy from the environment required to power these processes, and why ion concentration gradients across membranes are believed to play the central role in this context.
Dark Matter Physics With Tiny Galaxies
Annika Peter
Ohio State University
Abstract: Dark matter accounts for one-quarter of the universe’s energy budget, but we don’t know what it is. The simplest paradigm for dark matter is that it is non-relativistic, stable, and barely interacting with itself or anything else — a paradigm we call cold dark matter. Many popular particle physics models of dark matter behave cosmologically as cold dark matter. In terms of how structures in our universe form and grow, one of the strongest predictions of the standard cold dark matter paradigm is that there exists a hierarchy of structure down to Earth-mass scales. Other models of dark matter deviate from these predictions on scales of small galaxies and below. However, individual self-bound structures of dark matter--"halos"--are difficult to detect directly. Instead, we use galaxies as lampposts for halos. By counting galaxies, we can measure the underlying population of dark matter halos. In this talk, I describe how we do this counting in practice, and how it leads to new insight into the physics of dark matter. I will show what my group is doing so far to address the problem, and what opportunities lie ahead in the wide-field surveys of the 2020's.
The Rise of Silicon Quantum Electronics
Jason R. Petta
UCLA
Abstract: Over twenty years ago, Daniel Loss and David DiVincenzo proposed using the spin of a single electron as a quantum bit. At the time of the proposal, it was not possible to trap a single electron in a semiconductor device and measure its spin, let alone demonstrate control of spin coherence. In this colloquium, I will give a broad overview of the physics of semiconductor spin qubits, highlighting mechanisms for coherent spin-spin interactions. At short distances, the exchange interaction allows for coherent coupling on ~100 nm length scales with fidelities up to 99.8% - a performance competitive with superconducting qubits. Our research group is also exploring the use of microwave frequency photons as mediators of long-range (centimeter-scale) spin-spin interactions. In addition to enabling fundamental studies of quantum coherent processes in the solid state, silicon spin qubits can potentially be scaled to large system sizes using industrial fabrication techniques.
The Beauty of Scattering Amplitudes
Zvi Bern
UCLA
Recipient of the 2023 Galileo Medal
Abstract: In this colloquium, I will present highlights of our understanding of scattering amplitudes in quantum field theory that led to my 2023 Galileo Medal together with long-time collaborators Lance Dixon (SLAC) and David Kosower (Saclay). I will explain the application of these ideas to various topics including elementary-particle collider physics, the relation of gravity with the other forces, and basic questions on gravity and related theories. I will also explain recent developments showing that the quantum nature of gravity is very useful as a starting point for obtaining state-of-the-art precision predictions for interacting black holes and other compact astrophysical objects.
Space is Time: Einstein’s Solution to the Origin of Consciousness and Intelligence
Katsushi Arisaka
University of California, Los Angeles
Abstract: How can we construct a conscious, stable 3D vision from
ever-changing, shaky 2D retinotopic images? The solution
was given by Einstein a century ago; the distance between
two points must be measured by the time required for a
signal to travel from one point to the other. In other words,
"space is time.” We reconstruct the external 3D space in our
brain by assigning three absolute times (= phases) through
slowly traveling brainwaves.
Thanks to this space-to-time conversion, our brain developed
a new strategy to navigate the “hyper-space” of language in
the wider frequency-time domain, allowing us to develop
intelligence and creativity. After a decade of investigation
from C. elegans and fruit flies to humans, working together
with > 800 undergraduate students, we have accumulated
overwhelming evidence to support this concept
Visualizing Helical Tunneling of Dirac Fermions
Vidya Madhavan
UIUC
Abstract: Incorporating relativistic physics into quantum tunneling can lead to exotic behavior such as perfect transmission via Klein tunneling, or apparent faster than light travel. The realization of massless Dirac Fermions in topological materials has provided a new avenue to explore their properties. In this talk I will describe an experiment that demonstrates another property of Dirac electrons i.e. `helical tunneling’, a process where spin-polarized electrons can be transmitted in a nominally time-reversal invariant fashion. I will describe our experiments where we use nanowires of the topological Kondo insulator, SmB6 to generate and measure spin-polarized currents of Dirac surface states. Using nanofabrication techniques, we attach SmB6 nanowires to the end of scanning tunneling microscope (STM) tips, effectively making a functional probe with atomic resolution. The tips are used to image the canonical spin density wave material, Fe1+xTe. STM images show a superstructure with the periodicity of the antiferromagnetic order, indicating spin- selective tunneling from the nanowire. We further confirm a smoking gun signature of Helical tunneling by imaging the contrast reversal of the antiferromagnetic order at opposite bias voltages. Our experiment demonstrates a new technique to probe spin properties of materials using the special tunneling properties of relativistic fermions and opens the door to the development of other nanowire based probes.
Gravitational Waves: From Discovery to a New Science
Barry C Barish
Caltech and UC Riverside
Abstract: The discovery of gravitational waves was reported from the Laser Interferometer Gravitational-wave Observatory (LIGO) one-hundred years after they had been predicted by Albert Einstein in 1916. The first detection was achieved by the simultaneous observation of the merger of binary black holes by two widely separated suspended-mass interferometers that had unprecedented sensitivity to the distortions of space-time of less than 1 part in 10-21. A third interferometer, Virgo, joined the two LIGO detectors in 2017, making triangulation possible to accurately determine the sky location of observed gravitational wave events. Then, the simultaneous observation of a binary neutron star merger opened the exciting new observational field of multi-messenger astronomy. The detectors are being incrementally improved, a new generation of even more sensitive ground based interferometers are planned, as well as complementary initiatives in space, and from accurate pulsar timing initiatives. The status and future prospects will be reviewed.
Thin-disk galaxy formation in the LCDM cosmology
James Bullock
UC Irvine
Abstract: Among the oldest unsolved questions in galaxy formation theory is why some galaxies are disks and some are not. The existence of thin disk galaxies, in particular, has stood as a long-standing challenge to hierarchical, CDM-based cosmologies. While simplified models of disk formation that relates galaxy angular momentum to dark matter angular momentum exists, these classic models are rooted in several simplifying assumptions, including the supposition that the angular momentum distribution of accreted material is highly coherent and aligned, without regard to the structure and mixing timescales of accreting gas. Moreover, disks formed in modern cosmological simulations do not track dark matter halo spin as expected from the classic picture. While disk galaxiesare far from ubiquitous in the local universe, there are surprising hints from JWST data that disks are more common than many expected at very early times. In this talk, I will present results from FIRE simulation analysis that provides insight into the physics of thin-disk galaxy formation. In particular, I will show that the mode of gas accretion from the circum-galactic medium (CGM) appears to be an important ingredient in shaping galaxy morphology, with “hot-mode” accretion being most advantageous for coherent angular momentum alignment and the formation of thin disks. Thick, irregular galaxy formation tends to be associated with cold-mode accretion.
Cosmology: What we know, what we don’t know and our grandest aspirations
Michael Turner
The University of Chicago, UCLA
Abstract: For most of the last century cosmology was the province of astronomers (mostly in California) and concerned itself with galaxies in an expanding universe. Beginning around 1980, ideas from particle physics began to enter cosmology, focused on events that took place during the first microsecond. Circa 2000, with the discovery of cosmic acceleration/dark energy and precision measurements of CMB anisotropy the current paradigm — LambdaCDM emerged, revealing deep connections between particle physics and cosmology. According to LCDM, the gravity of particle dark matter holds all structures together, the repulsive gravity of dark energy is speeding up the expansion and the quantum seeds for galaxies arose during a very early burst of accelerated expansion (inflation). Cosmology solved? Not exactly, we have no direct evidence for the dark matter particle; we don’t understand dark energy; and have no standard model for inflation (or evidence to support it). And our aspirations are even higher. Great time to be a cosmologist.
Metals, Strange Metals, and Bad Metals
Steve Kivelson
Stanford University
Abstract: The simplicity of the Fermi-liquid based theory of “normal metals” hides the fact that the existence of a Fermi surface underlies some of the most spectacular emergent phenomena in the natural world. Recently, a host of metallic behaviors have been identified that apparently cannot be accounted for in the framework of the conventional theory of metals – observed in material systems referred to as “strange metals,” “bad metals,” and various other names evocative of one or another anomalous property. Examples of systems in which unconventional metallic behaviors have been reported include the cuprite high temperature superconductors, twisted bilayer graphene, systems undergoing a quantum superconductor-to-metal or a metal-to-insulator transition, and near quantum-critical metals. This talk will start with a high-level perspective on the theory of conventional metals, followed by a discussion of what makes the observed features of these unconventional metals so intriguing, ending with thoughts concerning some of the underlying physics implied by a subset of these observations.
Machine Learning Concepts for Inverse Design in Soft and Living Matter
Andrea Liu
University of Pennsylvania
Abstract: In order for artificial neural networks to learn a task, one must solve an inverse problem to find a network that produces the desired output. The method by which this problem is solved by computer scientists can be harnessed to solve inverse design problems in soft matter. I will discuss how we have used such ideas to design functional mechanical and flow networks, and to understand the process of dorsal closure during Drosophila development. I will also show how we can exploit physics to go beyond artificial neural networks by using local rules rather than global gradient descent approaches to learn in a distributed way without a processor. Andrea Liu is a theoretical soft and living matter physicist who received her A. B. and Ph.D. degrees in physics at the University of California, Berkeley, and Cornell University, respectively. She was a faculty member in the Department of Chemistry and Biochemistry at UCLA for ten years before joining the Department of Physics and Astronomy at the University of Pennsylvania in 2004, where she is the Hepburn Professor of Physics. She is a fellow of the APS, AAAS and the American Academy of Arts and Sciences, and a member of the National Academy of Sciences. Liu has served as Speaker of the Council of the American Physical Society (APS) and Chair of the Physics Section of the American Association for the Advancement of Science (AAAS) and is currently a Councilor of the US National Academy of Sciences and the AAAS.
Interactio Induced Magnetism in 2D Semiconductor Moiré Superlattices
Xiaodong Xu
University of Washington
Abstract: Many‐body interactions between carriers lie at the heart of correlated physics. The ability to tune such interactions would open the possibility to access and control complex electronic phase diagrams on demand. Recently, moiré superlattices formed by two‐dimensional materials have emerged as a promising platform for quantum engineering such phenomena. In this talk, I will present a systematic study of the emergent magnetic interactions (both antiferromagnetic and ferromagnetic) in strongly correlated transition metal dichalcogenides moiré superlattices. I will show that the combination of doping, electric field, and optical excitation provide dynamic controls of the rich many‐body Hamiltonian of moiré quantum matter.
SPARC and the High‐field Path to Fusion Energy
Dennis Whyte
MIT
Abstract: The advent of REBCO high‐temperature superconductors at commercial scale has changed the development path for producing fusion energy with magnetic confinement. The design and test of a large‐bore B>20 tesla peak field superconducting magnet at MIT PSFC, in collaboration with Commonwealth Fusion Systems, realizes a doubling of the allowed B field compared to previous state of the art. This realizes extremely large gains in fusion power density scales as B^4 and access to ignition as ~B^5 at fixed plasma physics. These gains in turn allow for operation away from limits, yet in much smaller and less expensive devices. CFS is presently constructing the high‐B tokamak SPARC outside Boston with MIT as its major scientific collaborator, with the goal of demonstrating high fusion energy gain and fusion power density that propels fusion into the commercial energy sector. In addition to describing SPARC, parallel key fusion technology development programs will be described.
Quantum Logic and Precision Measurements with Atoms and Molecules
David Leibrandt
UCLA
Abstract: We are presently in the midst of the second quantum revolution, in which control of the quantum mechanical degrees of freedom of individual atoms, molecules, and even macroscopic systems is being realized with ever improving fidelity and across increasingly large ensembles of entangled quantum systems. In this talk, I will begin with a brief overview of the various quantum computing platforms being developed at UCLA and elsewhere, including the first experimental demonstration of two-qubit gates which grew out of efforts to improve the precision of trapped-ion atomic clocks at NIST. Next, I will describe how two-qubit gates are used to enable atomic clocks based on aluminum ions that presently hold the record for the highest accuracy of any precision measurement experiment, and preliminary efforts towards building atomic clocks based on large ensembles of entangled ions with precision beyond the standard quantum limit. Finally, I will present experiments in which the quantum-logic spectroscopy techniques developed for aluminum clocks are used to achieve control of molecular ions, with applications in both quantum information as well as precision measurements. In particular, molecules can be used to search for very small deviations from the predictions of the Standard Model across several sectors, offering a tool to search for beyond Standard Model physics complementary to particle accelerators.
The Structure of the Nucleon
Haiyan Gao
Brookhaven National Laboratory and Duke University
Abstract:Nucleons (protons and neutrons) are the building blocks of atomic nuclei and are responsible for more than 99% of the visible matter in the universe. Despite decades of efforts in studying the structure of the proton, there are still interesting puzzles surrounding the proton, such as its spin and the charge radius. The proton mass is another fascinating topic, as most of the proton mass has little to do with the mass of its constituents. In this talk, I will review some recent advances in the study of the nucleon structure, and then discuss future studies with an Electron-Ion Collider to be built at the Brookhaven National Laboratory in the coming decade.
Past, Present and Future Vision for High-Gradient Linear Accelerators and Its Applications to Future High-Energy Physics Machines, Light Sources, and Medical Instruments
Sami Tantawi
Stanford University
Abstract: We start with an overview of the history of high-gradient linear accelerator developments that took place over the span of more than three decades to pave the way for a future collider to explore the energy frontier of high-energy physics. We then present an overview of recent advances in high-gradient linear accelerators operating at room temperature and cryogenic temperatures. We will include the advances that enabled us to understand better the underlying fundamental physics that governs the breakdown phenomena in high- field vacuum structures. With this new understanding, recent advances in linac topologies, materials, and operating temperatures started to emerge. We will review these and present a vision for future energy frontier machines and future light sources. The vision for this future research and development will include the core effort on the linacs, RF sources, and other auxiliary components, with the goal of optimizing the overall system performance and cost rather than the optimization of individual component independently. These advances also promise to revolutionize many other applications in the near future, including medical radiotherapy devices. We will explore the ongoing effort on this front, especially the possibilities for realizing the so-called “flash treatment.”
Early Science from the James Webb Space Telescope
Tommaso Treu
UCLA
In just two months, JWST has revolutionized our understanding of the universe. Its unprecedented sensitivity and angular resolution have given us a new view of the cosmos, enabling new discoveries in many areas of astronomy. I will describe the first results from my GLASS-JWST Early Release Science Program. The primary goal of the program is to understand how the first galaxies form, grow, and cause the last major phase transition of the universe, called "cosmic reionization". The second major goal of GLASS-JWST is understanding how heavy elements such as Carbon and Oxygen were formed out of the pristine gas leftover from the Big Bang and dispersed into the cosmos. Highlights include: i) the discovery of a hitherto unknown population of luminous galaxies at z>10, indicating that galaxies formed earlier and faster than previously thought; ii) the discovery of strongly inverted metal gradients in low mass galaxies, unexpected in galaxies formation models. I will also describe a number of other discoveries and surprises, including a highly magnified star billions of light years away, a very cool brown dwarf, and a supernova at z>3.
The Beginning of Helioseismology and Studies of Solar Dynamics
Roger K. Ulrich
UCLA
Helioseismology began with the 1962 report by Leighton, Noyes, and Simon announcing the discovery of the 5-minute oscillations. The discovery happened before I was a professional astronomer. I was a graduate student at UC Berkeley working on convection in Louis Henyey's group studying stellar structure and evolution. As I was nearing completion of the thesis, John Bahcall visited and suggested we should compute a solar model. I computed a solar model, sent it to John and was greeted by return mail with a list of things that had to be fixed. Fellow students and I did the fixes and published a paper. Meanwhile, I got an invitation from John to come to Cal Tech and work on computing solar models.
My interest in the solar 5-minute oscillations began with observations by fellow graduate student Ed Frazier which showed that the oscillatory motion was disrupted by convection cells rather than being generated. Based convective envelope which showed that the on that clue, I did a modal analysis of a model oscillatory power should be restricted to frequencies that depend on the horizontal wavelength. This prediction eventually led to the development of Helioseismology which in turn led to Asteroseismology. I will review the high points instruments of the prediction verification and subsequent development of the space-based now serving as the basis for helioseismology.
After 1985 I accepted the responsibility for managing the program of observations at the 150-foot solar tower telescope on Mt. Wilson. Consequently, after that date I stopped doing helioseismology and began studying solar surface dynamics and magnetic fields. These studies continue and I have recently found a new variations of velocities near the rotation which have timing closely related to the solar cycle.
Quantum Simulation, Sensing, and Computation With Ultracold Atoms
Dan Stamper-Kurn
UC Berkeley
Abstract: Ultracold atomic gases are perhaps the coldest matter in the universe, reaching temperatures below one nano-kelvin. At these low temperatures, noise is ironed out and the quantum mechanical properties of atoms, not only of their internal atomic states but also of their center-of-mass motion, become accessible and visible. I will describe applications of this ultracold quantum material in the areas of quantum simulation, sensing, and computation. Specifically, I will show how quantum gases far from equilibrium allow us to probe geometric singularities in band structure, a quantum simulation of condensed matter. I will describe how single atoms, trapped tightly within optical tweezers, can be serve as quantum sensors within a scanning-probe microscope of optical fields. Finally, I will explain how cavity-enhanced detection allows us to make mid-circuit measurements within an atoms-based quantum computing platform, a step toward quantum error correction. And what's next? Feedback control of quantum systems? Electromagnetic vacuum fluctuations serving as a chemical catalyst? Telecom-frequency optical clocks? Simulation of flat-band ferromagnetism? Perhaps all of the above.
Magnetic Chirality
Sang-Wook Chenog
UCLA
Chirality with all broken mirror symmetries, combined with any spatial rotations, matters ubiquitously from DNA functionality, vine climbing, to the piezoelectricity of quartz crystals. Chirality does not necessarily involve the presence of screw-like twisting, and magnetic chirality means chirality in spin ordered states or mesoscopic spin textures. Magnetic chirality does not change with time reversal operation, and chirality prime (ℯ′) means that time reversal symmetry in addition to all mirror symmetries, combined with any spatial rotations, are broken. In the case of ℯ′, there exist two kinds: type-I ℯ′ with unbroken “space inversion ⊗ time reversal” and type-II ℯ′ with broken “space inversion ⊗ time reversal”. Four examples of magnetic chirality will be discussed: helical spin state, magnetic toroidal moment combined with canted moment, magnetic quadruple moment combined with alternating canted moments, and Bloch-type skyrmions. We will also discuss a few examples of type-I ℯ′ type-ℯ′, and the emergent physical phenomena of ℯ and ℯ′ such as self-inductance, magnetooptical Kerr effect, anomalous Hall effect and linear magnetoelectricity. Some of these exotic phenomena have been recently observed, and many of them need to be experimentally confirmed in the future.
How Our Immune System Learns From a Changing Experience
Shenshen Wang
UCLA
Our adaptive immune system is able to learn from past experience to better fit an unforeseen future. This is made possible by a diverse and dynamic repertoire of cells expressing unique antigen receptors and capable of rapid Darwinian evolution within an individual. However, naturally occurring immune responses exhibit limits in efficacy, speed and capacity to adapt to novel challenges. In this talk, I will discuss theoretical frameworks we developed to (1) explore functional impacts of non-equilibrium antigen recognition, and (2) identify conditions under which natural selection acting local in time can find adaptable solutions favorable in the long run, through exploiting environmental variations and physical constraints. Using these examples, I show that a generalized landscape theory provides a unifying framework for understanding non-equilibrium processes across scales. In light of coevolution, I will discuss a broader scope of our work and its implications for vaccine strategies. I hope to convey that physicists can make a unique contribution to understanding systems as complex as the immune system – it is an exciting time to do so.
Next Generation Control and Acquisitions Platforms for Studying Large-Scale Neural-Behavioral Dynamics in Freely-Behaving Animals
Daniel Aharoni
UCLA
Next generation control and acquisitions platforms for studying large-scale neural-behavioral dynamics in freely-behaving animals A major challenge in neuroscience is to uncover how defined neural circuits in the brain encode, store, modify, and retrieve information. Adding to this challenge is the fact that neural function does not operate in isolation from but rather within living, behaving animals. Great technological advances over the past decades have allowed researchers to begin to optically measure and modulate neural activity but these approaches are often limited to head-fix animals when studying neural function at spatial and temporal scales relevant to internal neural circuit dynamics. While a great deal of scientific and technological progress has been made, there is still much to learn concerning complex neural function, especially within the context of natural behavior. To tackle this challenge, significant advancement of neural, behavioral, and computational tools is needed along with new experimental approaches to enable the detailed study of neural circuits within the context of complex behavior and naturalistic, ethologically relevant environments. Here, I will present our ongoing work leading the UCLA Miniscope Project, an open-source collaborative effort aimed at accelerating innovation of neural-behavioral technology while also democratizing access to these transformative tools. This talk will specifically focus on what I hope the future of neural-behavioral research looks like, the critical role engineering and physics will play in reaching this future, and projects my lab is currently working on to address underlying obstacles within modern neural-behavioral research.
Aspects of Symmetry in Quantum Field Theory — a Modern Update
Thomas Dumitrescu
UCLA
Abstract: Symmetry has long been a transformative notion in physics, starting with classical and quantum mechanics, but it really comes into its own in quantum field theory (QFT). QFT is a powerful framework for describing interacting systems with many degrees of freedom that serves as a unifying language across many areas of modern physics, including particle physics and string theory, as well as condensed matter and statistical physics. I will present a modern perspective on the notion of symmetry in QFT, with an eye toward recent developments that have greatly expanded this notion. I will then show how symmetries (both old and new) can be applied to gain deeper insight into the dynamics of interesting, strongly-coupled QFTs in diverse dimensions.
What Does Optimal Teaching and Learning Look Like?
Joshua Samani
UCLA
Abstract: Improving teaching and learning is a hard, complex problem that benefits from knowledge of the science of human learning. I'll present some of the most robust, generalizable effects from the known science of how people learn and how those effects can inform university-level teaching and learning. I'll then discuss a big, largely-unanswered question in the field followed by work at UCLA attempting to contribute to answering it.