Heilborn Lectures
2025-26 Heilborn Lecturer
Sean Carroll
Homewood Professor of Natural Philosophy, Johns Hopkins University
Fractal Faculty, Santa Fe Institute
Lectures:
Tuesday, April 21, 2026
Time and location TBA
Explaining the Arrow of Time
Abstract: Over a century ago, Boltzmann and others provided a microscopic understanding for the tendency of entropy to increase. But this understanding relies ultimately on an empirical fact about cosmology: the early universe had a very low entropy. Why was it like that? Cosmologists aspire to provide a dynamical explanation for the observed state of the universe, but have had very little to say about the dramatic asymmetry between early times and late times. I will discuss cosmological models that attempt to address this problem, and some ways that the arrow of time plays out in cosmic evolution.
Wednesday, April 22, 2026
Time and location TBA
Extracting the Universe from the Wave Function
Abstract: Quantum mechanics is a theory of wave functions in Hilbert space. Many features that we generally take for granted when we use quantum mechanics -- classical spacetime, locality, the system/environment split, measurement, preferred observables, the Born rule for probabilities -- should in principle be derivable from the basic ingredients of the quantum state and the Hamiltonian. I will discuss recent progress on these problems, including consequences for emergent spacetime and quantum gravity.
Public Lecture:
Friday, April 24, 2026
Time and location TBA
The Many Worlds of Quantum Mechanics
Abstract: One of the great intellectual achievements of the twentieth century was the theory of quantum mechanics, according to which observational results can only be predicted probabilistically rather than with certainty. Yet, after decades in which the theory has been successfully used on an everyday basis, most physicists would agree that we still don't truly understand what it means. I will talk about the source of this puzzlement, and explain why an increasing number of physicists are led to an apparently astonishing conclusion: that the world we experience is constantly branching into different versions, representing the different possible outcomes of quantum measurements. This could have important consequences for quantum gravity and the emergence of spacetime.
Sean Carroll's official title is Homewood Professor of Natural Philosophy at Johns Hopkins, and he is also Fractal Faculty at the Santa Fe Institute. He is interested in how the world works at the deepest levels, which leads him to do research in physics and philosophy. His current interests include foundational questions in quantum mechanics, spacetime, statistical mechanics, complexity, and cosmology, with occasional dabblings elsewhere.
To learn more about the Heilborn Lectures and for a list of past Lectures, click here.