View a 13-minute Video about the Aspen Center for Physics
  • June 17, 2021
    SARS-CoV2 and mRNA Vaccines by the (Bio)Numbers
    Speaker: Nic Vega, Emory University
    The dizzying abundance of information on SARS-CoV-2/COVID-19 and the new mRNA vaccines is difficult to navigate, even for experts, and mis-interpretations of these data are widespread. This talk will take an interdisciplinary approach to the current state of knowledge about the virus and the novel mRNA vaccines, with a special focus on the biophysics of coronavirus interactions with the host, to provide an educated non-specialist with a working conceptual model to better understand this disease.
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  • June 24, 2021
    The Mysterious Moun: the Electron's Heavy Sibling
    Speaker: Aida El-Khadra, University of Illinois, Urbana-Champaign
    More than eighty years after the muon was first discovered, it is still a source of mystery. Indeed, experiments are underway that use muons as a window to search for new particles or forces — a central goal of the high energy physics community.  These efforts build on a long-standing, tantalizing tension between experiment and theory for the muon’s magnetic properties. With the new measurement by the Fermilab g-2 experiment, announced on April 7, 2021, the significance of the tension is now a very strong hint for new physics, but still shy of discovery. After a tour of the muon's history, I will discuss the ongoing interplay between theory and experiment that is essential for unlocking the discovery potential of this mysterious particle
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  • July 1, 2021
    Patterns in Posture: Chaotic Worms and Other Surprises from the Physics of Animal Behavior
    Speaker: Greg Stephens, Vrije Universiteit Amsterdam
    While the science of the living world is largely focused on the microscopic - say the expression of genes or the pattern of electrical activity among our nerve cells -  these processes serve the greater evolutionary goals of the organism: to find food, avoid predators and reproduce.  But how do we quantify the dynamics of entire organisms? What principles characterize living movement? Here I describe how the combination of computer vision for high-resolution posture measurement with theoretical ideas from physics has enabled new understanding of the behavior of organisms in natural motion.  I illustrate this approach with animals of varying complexity, including in the nematode worm C. elegans where we find that variability in posture movements results, remarkably, from deterministic chaos.
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  • July 8, 2021
    Taking the First Picture of a Black Hole
    Speaker: Dimitrios Psaltis, University of Arizona

    The Event Horizon Telescope recently revealed the first picture of the black hole in the center of the M87 galaxy. This was the culmination of many technological and astrophysical advances that took place during the last two decades. In this presentation, I will discuss the coordinated efforts by more than 300 researchers in all continents that it took to generate this first picture with many anecdotes and inside stories. I will also present our best understanding of what this picture means for black holes and for Einstein’s general theory of relativity.
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  • July 15, 2021
    Understanding Solids with Supercomputers, Many Electrons at a Time
    Speaker: Cyrus Dreyer, Stonybrook University
    According to visionary American physicist Richard Feynman, the most important concept in all of science is "the atomic hypothesis that all things are made of atoms — little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another.” The properties of the materials that make up the world around us are governed by how these atoms attract and repel each other, which is determined by interactions between the electrons most loosely-bound to those atoms. For example, whether a solid is hard and translucent like diamond, or soft and opaque like graphite; whether a material conducts electricity and heat like copper, or prevents the flow of electricity and heat like rubber; whether a material can be used in computer chips, like silicon; or whether a drug like aspirin will mitigate a fever.

    Understanding these interactions turns out to be a very difficult problem, one that has challenged physicists for a century. For one thing, electrons are small, and thus governed by the weird properties of quantum mechanics. Also, there are a lot of them in a given material: there are more electrons in the atoms that make up a paper clip than there are stars in the universe. In this talk I will describe a particular approach to tackling the “many electron problem”, known as Density Functional Theory, which, combined with the most powerful supercomputers in the world, has revolutionized our ability to describe and predict the properties of materials. I will give a variety of examples of how this knowledge of materials can be used to develop novel electronic devices for modern technology.
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  • July 22, 2021
    Faster than Light: Spooky Action at a Distance in Nature
    Speaker: Mark Alford, Washington University in St. Louis
    Quantum mechanics is a famously weird theory, including strange phenomena like indeterminism and influences that travel faster than light. In the last few decades, scientists have performed "Einstein-Podolsky-Rosen" (EPR) experiments which have shown that these faster-than-light phenomena really occur in nature. In this talk I will explain in simple non-mathematical terms how EPR experiments achieve this surprising result, and how they relate to the well known principle of Einstein's theory of relativity that nothing can travel faster than light.
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  • July 29, 2021
    The Flavors of Particle Physics
    Speaker: Peter Onyisi, University of Texas Austin 
    The world we see is made up of just three kinds of fundamental particles of matter - electrons, up quarks, and down quarks - arranged in a dizzying number of combinations. However, for over eighty years, we have known of the existence of mysterious, heavy, short-lived siblings of these particles, and the almost-invisible neutrinos, that can only be seen in particle physics experiments. Although their lives are incredibly fleeting, understanding these other kinds of matter is essential if we are to grasp the big picture of how the universe works. I will discuss how we came to find these various "flavors" of particles, what we have learned so far about nature from them, and recent hints that some of them may not be behaving quite as we expect them to.
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  • August 5, 2021
    The Cosmic Cocktail: Three Parts Dark Matter
    Speaker: Katherine Freese, University of Texas Austin
    The ordinary atoms that make up the known universe, from our bodies and the air we breathe to the planets and stars, constitute only 5% of all matter and energy in the cosmos. The remaining 95% is made up of a recipe of 25% dark matter and 70% dark energy, both nonluminous components whose nature remains a mystery.   Katherine Freese will recount the stories of the dark matter puzzle, starting with the discoveries of visionary scientists from the 1930s who first proposed its existence, to Vera Rubin in the 1970s whose observations conclusively showed its dominance in galaxies, to the deluge of data today from underground laboratories, satellites in space, and the Large Hadron Collider. Theorists contend that dark matter most likely consists of new fundamental particles; the best candidates include WIMPs (weakly interacting massive particles), axions, or light or fuzzy dark matter. Billions of them pass through our bodies every second without us even realizing it, yet their gravitational pull is capable of whirling stars and gas at breakneck speeds around the centers of galaxies, and bending light from distant bright objects.  This talk will overview this cosmic cocktail, including the evidence for the existence of dark matter in galaxies. Many cosmologists believe we are on the verge of solving this mystery and this talk will provide the foundation needed to fully fathom this epochal moment in humankind's quest to understand the universe.
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  • August 19, 2021
    Puzzles in the Milky Way's Highest-Energy Light
    Speaker: Tracy Slatyer, MIT
  • Gamma rays, with frequencies billions of times higher than visible light, provide a window on extremely energetic astrophysical processes occurring in our Milky Way Galaxy. In recent years, gamma-ray observations have revealed giant figure-eight-shaped gamma-ray structures known as the Fermi Bubbles, which may have erupted from the giant black hole at the center of our Galaxy. At the same time, a mysterious glow of gamma-rays from the inner Galaxy may hold clues to a new population of rapidly-spinning neutron stars, or even to the puzzle of dark matter. I will discuss these signals and what they may teach us about our Galaxy and universe. 
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  • August 26, 2021
    Atoms and Photons: from Fundamental Physics to Quantum Technology
    Speaker: Monika Schleier-Smith, Stanford University
    The power of quantum information lies in its capacity to be non-local, encoded in correlations among entangled particles.  Yet our ability to produce, understand, and exploit such correlations is hampered by the fact that the interactions between particles are ordinarily local.  To circumvent this limitation in the laboratory, we let distant atoms “talk” to each other with the aid of photons that act as messengers.  This toolbox opens opportunities ranging from simulating quantum gravity to exploring new computational paradigms for problems intractable to classical computers.
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"I found the general atmosphere [at the Aspen Center for Physics] very stimulating. All practical matters were taken care of in a pragmatic and effective way, all time was available for discussions and self-study. The beautiful surroundings did not distract, but stimulated creative thinking. It is too bad that life cannot always be so simple and pleasant."