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Black Hole Initiative - Harvard University

The first worldwide center to focus on the study of black holes.

10/22/2026

BHI fellow Daine Danielson and BHI affiliate Gautam Satishchandran
have a new paper in the Physical Review.

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Horizons and soft quantum information

Publication: Physical Review D, Vol 114, Issue 8
Publication Date: October 6, 2026
Authors: Daine L. Danielson and Gautam Satishchandran

It was recently shown that black holes decohere any quantum superpositions in their vicinity. This decoherence is mediated by soft radiation through the horizon, and can be understood as the result of the fact that quantum states in the exterior source distinguishable states of long-range fields in the interior. To study this phenomenon and others, we extend Tomita-Takesaki theory to accommodate states of soft radiation such as arise in the electromagnetic and gravitational memory effects, and provide a general framework for computing the distinguishability of general coherent states. Applying these tools, we use the methods of unambiguous state discrimination and approximate quantum error correction to prove some new relations regarding the distinguishability of quantum states, and the quantum information content of soft radiation, and thereby show that a black hole (or, under the conditions stated below, any causal horizon) decoheres its environment as though its interior were full of optimal observers.

10/21/2026

Please join us on 10.26.26 at 9:30 a.m. for our next Foundations Seminar with Sebastian Fernandez-Mulligan from Yale.

Sebastian will be presenting in person. Light breakfast available.

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Intuition and Algorithms in Observational Astronomy

In this talk, I will use the history of gravitational lensing in observational astronomy to explore the role of human intuition in an age of algorithmic inference. Between the late 1970s, when the first gravitational lens was observed, and the 2010s, astronomers discovered only a few hundred strong lenses. To find these sources, scientists relied on visual intuition. With a vast amount of sky survey data, fast visual analysis (just a few seconds per image!) was a key aspect in the data-processing pipeline. In a glance, the trained astronomer could spot a lens while combing through a survey. This is changing. The launch of Euclid in 2023 marked the onset of a project that forecasted it would find over 100,000 lenses in its 6-year mission. The oncoming deluge will overwhelm even the quick glance, and recent work has focused on developing and deploying algorithms that can automate the search. Yet, this has not spelled the end for the intuitive eye. Moving from the 1970s to the present, I will trace how astronomers cultivated a specific form of visual intuition, the well-trained glance, and how this skill has become even more important within the infrastructure of automated data processing. Recognizing the persistence of intuition, I contend, raises new questions about how we integrate algorithms into scientific practice.

10/20/2026

Please join us on 10.26.26 at 11 a.m. for our next Colloquium with Tim Adamo from the Univeristy of Edinburgh.

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Black Holes in Twistor Space

Twistor theory is a mathematical formalism which can be used to solve certain differential equations in terms of free analytic data. While twistor theory boasts many important achievements, a long-standing difficulty has been describing non-self-dual field configurations, a challenge referred to as "the googly problem." In this talk, I will describe a resolution of the googly problem for some black hole solutions of the Einstein equations, and try to convince you that this is interesting from several different perspectives.

10/16/2026

BHI fellow Simon Heuveline and BHI PI Andrew Strominger have a new paper on arXiv.

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The Conformal w-Algebra

Authors: Simon Heuveline, Nia Robles Del Pino and Andrew Strominger

Einstein gravity in four asymptotically flat dimensions is governed by a tower of soft theorems obeying an Lw1+∞ commutator algebra. This algebra is deformed to LΛw1+∞ in the conformally related AdS4 and dS4 spacetimes. Here we construct the larger ``conformal w-algebra", denoted Cw1+∞, which acts on conformal gravity in all of these spacetimes. It includes Lw1+∞, LΛw1+∞ and the so(4,2) 4D conformal algebra as subalgebras. We show that Cw1+∞ is the conformal completion of either Lw1+∞ or LΛw1+∞. A derivation of Cw1+∞ is given as the symmetry of the twistor action of self-dual conformal gravity.

10/15/2026

Please join us on 10.19.26 at 9:30 a.m. for our next Foundations Seminar with Patrick Ryan from New York University.

The Approximate Cosmological Principle and Permanent Underdetermination in Cosmology

In this talk, I will discuss the implications of some recent work in observational cosmology and mathematical general relativity (GR) for the epistemology of spacetime. My primary aim is to articulate a non-trivial and physically relevant underdetermination thesis concerning the global, topological structure of models of GR. I will argue that my thesis is philosophically interesting for at least two reasons: (i) it affects "sensible realists," viz., those who counsel realism only about theoretical claims that are amenable to empirical investigation (Stanford 2006); and (ii) it is "permanent" (in the sense of Pitts 2011). In order to formulate my thesis and to defend my claims, I begin by surveying cosmological research devoted to empirically determining the spatial topology of the universe (e.g., Akrami et al. 2024). This research typically assumes the Cosmological Principle (CP); however, CP is a very strong constraint on our theorizing, and its justification is fraught with difficulties. Indeed, strictly speaking, it is known not to hold, even in the observable universe. As such, it has been suggested that a more accurate reflection of our observational situation would be to assume an "approximate" CP. Drawing on recent mathematical work, I discuss one possible way of making this notion precise (Ringström 2013). Interestingly, when we pass to Ringström's approximate CP, it appears that one cannot draw any conclusions about the topology of space. I carefully analyze why this occurs, and demonstrate that the resulting underdetermination is permanent. Time permitting, I compare my thesis to related results and sketch how my discussion can serve as a powerful starting point for anti-realist positions in the epistemology of spacetime.

10/14/2026

Please join us on 10.19.26 at 11 a.m. for our next Colloquium with Brenna Mockler from UC Davis.

Modeling emission from super-Eddington supermassive black holes

Tidal disruption events (TDEs) light up hidden supermassive black holes and encode information about the properties of both these black holes and their environments. They also regularly produce super-Eddington mass return rates, providing a local test of extreme black hole growth. The light curves and spectra of TDEs show signatures of these super-Eddington feeding rates, including evidence of large outflows, very high electron densities, and strongly ionizing but obscured emission. Many of these signatures are also seen in other candidates for super-eddington accretion, including luminous fast blue optical transients, ambiguous nuclear transients, and little red dots. However, properties of the system such as the origin, mass/energy budget and black hole mass are often better understood in TDEs. I’ll discuss how we can use theoretical models to connect the observed light curves and spectra to the actual source emission as well as to the properties of the gas surrounding the black hole in these transients. More broadly I’ll discuss how we can combine theoretical models with observations to investigate the black hole mass function, probe emission from forming and evolving accretion disks, and study the properties of stars on size scales we cannot observe outside our own galactic nuclei.

10/08/2026

We’re very pleased to have James Owen Weatherall in town on 10.13.26 for two talks: a special Foundations Seminar at the BHI followed by a talk for the Boston Network for the History and Philosophy of Physics (BNHPP) at Northeastern.

The BHI Foundations Seminar:
10:30 a.m.
BHI Conference Room
Zoom: https://bit.ly/46FEet2

The BNHPP talk
3:15/3:30 p.m.
Renaissance Hall, Room 909
Northeastern University
Zoom: https://bit.ly/4AZXnnM

The Boston Network for the History and Philosophy of Physics is launching its 2026–27 Colloquium Series this year. One of the series organizers is Jamee Elder, a BHI alum, and brings together scholars working across the history and philosophy of physics.

We hope you can join us for one or both of James’s talks!

10/06/2026

Next week, we’ll be observing Indigenous Peoples’ Day, so our Colloquium and Foundation Seminar lectures will take a week off.

Lectures will resume on October 19. We’ll see you then!

10/01/2026

BHI fellow Simon Heuveline, BHI visiting scholar Romain Ruzziconi, BHI graduate student Ahmed Sheta, and BHI PI Andrew Strominger have a new paper on arXiv.

https://bit.ly/4rHNuGY

Self-Dual Yang-Mills in AdS

Authors: Simon Heuveline, Romain Ruzziconi, Ahmed Sheta and Andrew Strominger

Quantum Yang-Mills theory in Euclidean AdS4 with Neumann boundary conditions is studied as a function of the complex couplings 1g2±≡1g2∓iθ8π2. We define a "self-dual limit" by g−→0 with g+ fixed. We argue that the limiting theory is well-defined perturbatively and equivalent to the BF formulation of self-dual Yang-Mills theory with a particular boundary condition relating B and F at the boundary ∂AdS4. g+ is the loop-counting parameter of the self-dual theory. This is in stark contrast to flat space, where θ has no effect on perturbative dynamics. In the self-dual limit, it is shown that all tree-level zero-plus and single-plus boundary correlators vanish. A closed form expression is given for any number of gluons for the double-plus tree correlators. Finally, we show that in the flat space limit of AdS4, the total energy poles in the tree boundary correlators correctly reduce to the single-minus gluon amplitudes.

# HighEnergyPhysics

09/30/2026

Please join us on 10.05.26 at 9:30 a.m. for our next Foundations Seminar with Daine Danielson from the BHI.

Daine will be presenting in person. Light breakfast available.

Measuring the Acceleration-Dependent Temperature of the Minkowski Vacuum

Relativistic quantum field theory is the structure on which the Standard Model and beyond-Standard Model physics are built. One of its most striking predictions is the Unruh effect: an accelerating observer measures the Minkowski vacuum as a thermal bath at a fixed temperature. Despite decades of theoretical interest, this effect has never been directly observed. We propose to use the high acceleration gradients provided by wakefield accelerators, coupled with a forward laboratory-frequency ~THz detector array, to measure the resulting forward-beamed radiation, and outline the unique signature provided by quantum detailed balance to extract the signal from backgrounds. While challenging, such a measurement appears within reach of present-day accelerator and detector technologies.

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https://bhi.fas.harvard.edu/, https://www.youtube.com/channel/UCeKr4Y4flol0SDcV3qNxj_w, https://www.instagram.com/blackh

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