About

David I. Kaiser is the Germeshausen Professor of the History of Science and Professor of Physics at MIT. His research focuses on early-universe cosmology, foundations of quantum theory, and the history of modern physics. Kaiser has authored several award-winning books on the history of physics, including 'Drawing Theories Apart: The Dispersion of Feynman Diagrams in Postwar Physics,' 'How the Hippies Saved Physics: Science, Counterculture, and the Quantum Revival,' and 'Quantum Legacies: Dispatches from an Uncertain World.' He co-directs a research group on early-universe cosmology with Alan Guth at the MIT Center for Theoretical Physics and has designed and helped conduct experimental tests of quantum theory. Kaiser is a Fellow of the American Physical Society and has received MIT's highest awards for teaching excellence. His work has been featured in prominent publications such as Science, Nature, the New York Times, and the New Yorker magazine, and his group's efforts in quantum entanglement testing were featured in a documentary film.

Research topics

• Physics
• Theoretical physics
• Computer science
• History
• Political science

Selected publications

• Shocks from Exploding Primordial Black Holes in the Early Universe

  CERN Document Server (European Organization for Nuclear Research) · 2026-03-16

  preprintOpen accessSenior author

  We investigate how Hawking radiation from low-mass primordial black holes deposits energy into the early-universe plasma and show that the resulting phenomena are hydrodynamic rather than purely diffusive. Combining analytic arguments with relativistic hydrodynamic simulations, we find that the plasma first develops a quasi-steady outflow during the slow evaporation stage, while the final runaway phase of evaporation produces an expanding fireball that launches a shock wave into the surrounding medium. We characterize the thermalization scale of the Hawking products, the conditions under which shocks form, and the evolution and propagation of shocks. Additionally, we show that these shocks can locally restore electroweak symmetry, identifying exploding PBHs as a potentially important source of out-of-equilibrium dynamics in the early universe with profound phenomenological implications.

  PublisherOA PDFDOI

• Baryogenesis from Exploding Primordial Black Holes

  arXiv (Cornell University) · 2026-03-30

  articleOpen accessSenior author

  Exploding primordial black holes can source baryon asymmetry soon after the electroweak phase transition, as high-energy Hawking radiation drives ultrarelativistic shocks in the surrounding plasma. The shocks and their trailing rarefaction waves delineate two bubble-like walls around a shell of superheated fluid, in which electroweak symmetry is restored. These moving interfaces source chiral charge, which is converted to baryon number. Upon adding a simple CP-violating operator at the TeV scale, this mechanism yields the observed baryon asymmetry with minimal dependence on PBH model parameters.

  PublisherOA PDF

• Gravitational Ionization by Schwarzschild Primordial Black Holes

  Open MIND · 2026-01-09

  preprintSenior author

  Primordial black holes (PBHs) are theorized to form from the collapse of overdensities in the very early Universe. PBHs in the asteroid-mass range $10^{17} \, {\rm g}\lesssim M \lesssim 10^{23} \, {\rm g}$ could serve as all or most of the dark matter today, but are particularly difficult to detect due to their modest rates of Hawking emission and sub-micron Schwarzschild radii. We consider whether the steep gradients of a PBH's gravitational field could generate tidal forces strong enough to disrupt atoms and nuclei. Such phenomena may yield new observables that could uniquely distinguish a PBH from a macroscopic object of the same mass. We first consider the gravitational ionization of ambient neutral hydrogen and evaluate prospects for detecting photon radiation from the recombination of ionized atoms. During the present epoch, this effect would be swamped by Hawking radiation -- which would itself be difficult to detect for PBHs at the upper end of the asteroid-mass window. We then consider the gravitational ionization and heating of neutral hydrogen immediately following recombination at $z\simeq1090$, and identify a broad class of PBH distributions with typical mass $5\times10^{21}\,{\rm g}\lesssim M \lesssim 10^{23}\, {\rm g}$ within which gravitational interactions would have been the dominant form of energy deposition to the medium. We also identify conditions under which tidal forces from a transiting PBH could overcome the strong nuclear force, either by dissociating deuterons, which would be relevant during big bang nucleosynthesis (BBN), or by inducing fission of heavy nuclei. We find that gravitational dissociation of deuterons dominates photodissociation rates due to Hawking radiation for PBHs with masses $10^{14}\,{\rm g}\lesssim M \lesssim 10^{16}\,{\rm g}$. We additionally identify the phenomenon of gravitationally induced fission of heavy nuclei via tidal deformation.

  DOI

• Shocks from Exploding Primordial Black Holes in the Early Universe

  ArXiv.org · 2026-03-16

  articleOpen accessSenior author

  We investigate how Hawking radiation from low-mass primordial black holes deposits energy into the early-universe plasma and show that the resulting phenomena are hydrodynamic rather than purely diffusive. Combining analytic arguments with relativistic hydrodynamic simulations, we find that the plasma first develops a quasi-steady outflow during the slow evaporation stage, while the final runaway phase of evaporation produces an expanding fireball that launches a shock wave into the surrounding medium. We characterize the thermalization scale of the Hawking products, the conditions under which shocks form, and the evolution and propagation of shocks. Additionally, we show that these shocks can locally restore electroweak symmetry, identifying exploding PBHs as a potentially important source of out-of-equilibrium dynamics in the early universe with profound phenomenological implications.

  PublisherOA PDF

• Baryogenesis from Exploding Primordial Black Holes

  CERN Document Server (European Organization for Nuclear Research) · 2026-03-30

  preprintOpen accessSenior author

  Exploding primordial black holes can source baryon asymmetry soon after the electroweak phase transition, as high-energy Hawking radiation drives ultrarelativistic shocks in the surrounding plasma. The shocks and their trailing rarefaction waves delineate two bubble-like walls around a shell of superheated fluid, in which electroweak symmetry is restored. These moving interfaces source chiral charge, which is converted to baryon number. Upon adding a simple CP-violating operator at the TeV scale, this mechanism yields the observed baryon asymmetry with minimal dependence on PBH model parameters.

  PublisherOA PDFDOI

• Gravitational Ionization by Schwarzschild Primordial Black Holes

  arXiv (Cornell University) · 2026-01-09

  articleOpen accessSenior author

  Primordial black holes (PBHs) are theorized to form from the collapse of overdensities in the very early Universe. PBHs in the asteroid-mass range $10^{17} \, {\rm g}\lesssim M \lesssim 10^{23} \, {\rm g}$ could serve as all or most of the dark matter today, but are particularly difficult to detect due to their modest rates of Hawking emission and sub-micron Schwarzschild radii. We consider whether the steep gradients of a PBH's gravitational field could generate tidal forces strong enough to disrupt atoms and nuclei. Such phenomena may yield new observables that could uniquely distinguish a PBH from a macroscopic object of the same mass. We first consider the gravitational ionization of ambient neutral hydrogen and evaluate prospects for detecting photon radiation from the recombination of ionized atoms. During the present epoch, this effect would be swamped by Hawking radiation -- which would itself be difficult to detect for PBHs at the upper end of the asteroid-mass window. We then consider the gravitational ionization and heating of neutral hydrogen immediately following recombination at $z\simeq1090$, and identify a broad class of PBH distributions with typical mass $5\times10^{21}\,{\rm g}\lesssim M \lesssim 10^{23}\, {\rm g}$ within which gravitational interactions would have been the dominant form of energy deposition to the medium. We also identify conditions under which tidal forces from a transiting PBH could overcome the strong nuclear force, either by dissociating deuterons, which would be relevant during big bang nucleosynthesis (BBN), or by inducing fission of heavy nuclei. We find that gravitational dissociation of deuterons dominates photodissociation rates due to Hawking radiation for PBHs with masses $10^{14}\,{\rm g}\lesssim M \lesssim 10^{16}\,{\rm g}$. We additionally identify the phenomenon of gravitationally induced fission of heavy nuclei via tidal deformation.

  PublisherOA PDF

• Primordial Black Holes from Inflation with a Spectator Field

  ArXiv.org · 2025-12-03

  preprintOpen access

  How is the production of primordial black holes (PBHs) in single-field models of inflation impacted by the presence of additional scalar fields? We consider the effect of a spectator field - a free scalar field with sub-Hubble mass, no direct coupling to the inflaton, and which makes a subdominant contribution to the total energy density - in the context of single-field models of inflation featuring a transient phase of ultra-slow roll (USR) evolution. Despite the modest title, a spectator field can have a dramatic impact: the slow-roll evolution of the spectator prevents the combined inflaton-and-spectator system from entering into USR, which naively might be expected to preclude the production of PBHs. However, we demonstrate that the growth of perturbations is maintained or enhanced by the spectator, through the rich interplay of curvature and isocurvature perturbations. We show in a model-independent way that the single-field phase of ultra-slow-roll is replaced by two turns in field space encompassing a phase of tachyonic instability for the isocurvature perturbations and a transfer of power from isocurvature to curvature modes. Furthermore, we highlight a degeneracy between the fine-tuning of the feature in the inflaton potential and the parameters of the spectator, leading to an overall resilience of model predictions to parameter variations. This makes it easier for the underlying PBH model to accommodate both high-precision CMB constraints and production of PBHs in the asteroid-mass range.

  PublisherOA PDFDOI

• Polarization observables in double neutral pion photoproduction

  The European Physical Journal A · 2025-07-23 · 4 citations

  articleOpen access

  Abstract Measurements of target asymmetries and double-polarization observables for the reaction "Equation missing" are reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility (Bonn University) using the Bonn frozen-spin butanol ( $$\hbox {C}_4\hbox {H}_9$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>C</mml:mtext> <mml:mn>4</mml:mn> </mml:msub> <mml:msub> <mml:mtext>H</mml:mtext> <mml:mn>9</mml:mn> </mml:msub> </mml:mrow> </mml:math> OH) target, which provided transversely polarized protons. Linearly polarized photons were produced via bremsstrahlung off a diamond crystal. The data cover the photon energy range from "Equation missing" to "Equation missing" and nearly the complete angular range. The results have been included in the BnGa partial wave analysis. Experimental results and the fit agree very well. Observed systematic differences in the branching ratios for decays of "Equation missing" and $${\varDelta ^*}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>Δ</mml:mi> <mml:mo>∗</mml:mo> </mml:msup> </mml:math> resonances are attributed to the internal structure of these excited nucleon states. Resonances which can be assigned to SU(6) $$\times $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>×</mml:mo> </mml:math> O(3) two-oscillator configurations show larger branching ratios to intermediate states with non-zero intrinsic orbital angular momenta than resonances assigned to one-oscillator configurations.

  PublisherOA PDFDOI

• Ultrahigh-Energy Neutrinos from Primordial Black Holes

  Physical Review Letters · 2025-09-18 · 21 citations

  articleOpen accessSenior author

  The KM3NeT Collaboration recently announced the detection of a neutrino with energy 220 PeV. One possible source of such ultrahigh-energy particles is the rapid emission of energetic Hawking radiation from a primordial black hole (PBH) near the end of its evaporation lifetime. The mass distribution for PBHs features a power-law tail for small masses; a small subset of PBHs would be undergoing late-stage evaporation today. We find that recent high-energy neutrino events detected by the IceCube and KM3NeT Collaborations, with energies O(1-10^{2}) PeV, are consistent with event-rate expectations if a significant fraction of the dark matter consists of PBHs.

  PublisherDOI

• Gravitational wave signals from primordial black holes orbiting solar-type stars

  Physical review. D/Physical review. D. · 2025-09-30 · 4 citations

  articleOpen access

  International audience

  PublisherOA PDFDOI

Recent grants

• Postdoctoral Fellowships: Andrew Friedman: "Dark Energy, Fine-Tuning, and the Multiverse: Testing Theories in Modern Cosmology"

  NSF · $120k · 2011–2014

• INSPIRE: Testing Bell's Inequality with Astrophysical Observations

  NSF · $900k · 2015–2021

Frequent coauthors

• Lynda Thompson

  ADD Centre

  27 shared

• Joel F. Lubar

  University of Tennessee at Knoxville

  26 shared

• Jon Frederick

  Middle Tennessee State University

  26 shared

• Curtis Cripe

  University of Tennessee at Knoxville

  25 shared

• Jay Gunkelman

  25 shared

• Rex Cannon

  25 shared

• Michael Thompson

  International Institute for Applied Systems Analysis

  25 shared

• Michael Hollifield

  Tibor Rubin VA Medical Center

  25 shared

Labs

• MIT Center for Theoretical Physics – a Leinweber InstitutePI

Education

• Ph.D., Physics

  Harvard University

  2000

Awards & honors

• 2021 // Quantum Legacies: Dispatches from an Uncertain World…
• 2016 // George Sarton Memorial Lecturer, History of Science…
• 2013 // Davis Prize (History of Science Society) for best bo…
• 2012 // Physics World Magazine "Book of the Year" Award
• 2012-22 // Margaret MacVicar Faculty Fellow, MIT (Honors MIT…