David I. Kaiser is an American

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

and

historian of science The history of science covers the development of science from ancient history, ancient times to the present. It encompasses all three major branches of science: natural science, natural, social science, social, and formal science, formal. Pr ...

. He is Germeshausen Professor of the History of Science at the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...

(MIT) and a full professor in MIT's department of physics. He also served as an inaugural associate dean for MIT's cross-disciplinary program in Social and Ethical Responsibilities of Computing. Kaiser is the author or editor of several books on the history of science, including ''Drawing Theories Apart: The Dispersion of Feynman Diagrams in Postwar Physics'' (2005), ''How the Hippies Saved Physics: Science, Counterculture, and the Quantum Revival'' (2011), and ''Quantum Legacies: Dispatches from an Uncertain World'' (2020). He received the Apker Award from the

American Physical Society The American Physical Society (APS) is a not-for-profit membership organization of professionals in physics and related disciplines, comprising nearly fifty divisions, sections, and other units. Its mission is the advancement and diffusion of ...

in 1993 and was elected a Fellow of the

in 2010. His historical scholarship has been honored with the

Pfizer Award The Pfizer Award is awarded annually by the History of Science Society "in recognition of an outstanding book dealing with the history of science" that was "published in English during a period of three calendar years immediately preceding the ...

(2007)History of Science Society
"Pfizer Award"
and the Davis Prize (2013)History of Science Society
"Davis Prize"
from the

History of Science Society The History of Science Society (HSS), founded in 1924, is the primary professional society for the academic study of the history of science. The society has over 3,000 members worldwide. It publishes the quarterly journal ''Isis'' and the yearly ...

. In March 2012 he was awarded the MacVicar fellowship, a prestigious MIT undergraduate teaching award.Jesse Kirkpatrick
"Four MacVicar Recipients"
''The Tech'', 132(13). In 2012, he also received the Frank E. Perkins Award from MIT for excellence in mentoring graduate students.

Education

Kaiser completed his AB in physics at

Dartmouth College Dartmouth College ( ) is a Private university, private Ivy League research university in Hanover, New Hampshire, United States. Established in 1769 by Eleazar Wheelock, Dartmouth is one of the nine colonial colleges chartered before the America ...

in 1993. He completed two PhDs from

Harvard University Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...

. The first was in physics in 1997 for a thesis entitled "Post-Inflation Reheating in an Expanding Universe," the second in the history of science in 2000 for a thesis on "Making Theory: Producing Physics and Physicists in Postwar America."Kaiser CV
MIT, accessed January 13, 2023

MIT, accessed January 13, 2023.

Physics Research

Cosmic inflation

Kaiser's physics research mostly focuses on early-universe cosmology, including topics such as

cosmic inflation In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the very early universe. Following the inflationary period, the universe continued to expand, but at a slower ...

, post-inflation reheating, and primordial black holes. In particular, he and colleagues have studied a wide range of initial conditions under which inflation will begin, as well as constructing models of inflation that include features motivated by high-energy particle physics, such as multiple interacting fields with nonminimal couplings to spacetime curvature. This work includes some of the first calculations of predictions from such models for observable features such as the spectral index of primordial perturbations measured in the

cosmic microwave background The cosmic microwave background (CMB, CMBR), or relic radiation, is microwave radiation that fills all space in the observable universe. With a standard optical telescope, the background space between stars and galaxies is almost completely dar ...

radiation, the first demonstration that resonant particle production during the reheating phase can persist amid an expanding universe, and the first demonstration of attractor behaviors in multifield models. More recent work has identified distinct processes within the late stages of the reheating phase, which ultimately yield the conditions for standard

Big Bang The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models based on the Big Bang concept explain a broad range of phenomena, including th ...

evolution: a hot plasma of

Standard Model The Standard Model of particle physics is the Scientific theory, theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions – excluding gravity) in the unive ...

particles in thermal equilibrium.

Primordial black holes

Some of Kaiser’s research focuses on primordial black holes, especially as a viable candidate for

dark matter In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relat ...

. Unlike various hypothetical particles, such as

weakly interacting massive particles Weakly interacting massive particles (WIMPs) are hypothetical particles that are one of the proposed candidates for dark matter. There exists no formal definition of a WIMP, but broadly, it is an elementary particle which interacts via gravity an ...

(WIMPs) or ultralight particles such as

axions An axion () is a hypothetical elementary particle originally theorized in 1978 independently by Frank Wilczek and Steven Weinberg as the Goldstone boson of Peccei–Quinn theory, which had been proposed in 1977 to solve the strong CP problem in ...

, primordial black holes would not require any new particles beyond the Standard Model in order to account for the measured dark matter abundance. Kaiser and his colleagues have studied mechanisms by which a population of primordial black holes could have formed during the very early universe in models that preserve the close fit between predictions and observations of the cosmic microwave background radiation. They have also identified a possible subpopulation of primordial black holes that would have formed with significant QCD color charge, constituting a novel state of matter. Additionally, they have proposed a new observable test to help establish whether primordial black holes exist and contribute significantly to dark matter abundance, based on high-precision measurements of visible objects within the Solar System, such as the planet Mars.

Experimental tests of quantum theory

Kaiser has also helped to design and conduct novel experimental tests of

quantum mechanics Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is ...

. In one such test, Kaiser and colleagues demonstrated how measurements of

neutrino oscillations Neutrino oscillation is a quantum mechanical phenomenon in which a neutrino created with a specific lepton family number ("lepton flavor": electron, muon, or tau) can later be measured to have a different lepton family number. The probability o ...

could be used to test whether quantum objects really persist in

superposition In mathematics, a linear combination or superposition is an expression constructed from a set of terms by multiplying each term by a constant and adding the results (e.g. a linear combination of ''x'' and ''y'' would be any expression of the form ...

states—akin to Schrödinger’s cat—between preparation and measurement. By applying the neutrino measurements to the Leggett-Garg inequality, their long-baseline test showed clear evidence of quantum superpositions over a distance of 450 miles. In a separate project, Kaiser and colleagues first proposed a novel protocol for experimental tests of

Bell’s inequality Bell's theorem is a term encompassing a number of closely related results in physics, all of which determine that quantum mechanics is incompatible with local hidden-variable theories, given some basic assumptions about the nature of measuremen ...

to address the so-called “freedom-of-choice” loophole. Working with Nobel laureate

Anton Zeilinger Anton Zeilinger (; born 20 May 1945) is an Austrian quantum physicist and Nobel laureate in physics of 2022. Zeilinger is professor of physics emeritus at the University of Vienna and senior scientist at the Institute for Quantum Optics and Qu ...

and his group,David Kaiser
"They probed quantum entanglement while everyone shrugged"
''Nautilus'', October 5, 2022. their “Cosmic Bell” experiments demonstrated

quantum entanglement Quantum entanglement is the phenomenon where the quantum state of each Subatomic particle, particle in a group cannot be described independently of the state of the others, even when the particles are separated by a large distance. The topic o ...

while using real-time astronomical measurements of cosmologically distant events to determine the types of measurements performed on each member of an entangled pair. These experiments placed the tightest constraints yet on certain types of alternative models to quantum theory, excluding nearly all possible exploitation of the freedom-of-choice loophole from the causal past of the experiments, extending from the Big Bang to today. The Cosmic Bell experiments were featured in the PBS NOVA documentary film ''Einstein’s Quantum Riddle'' (2019).

Historical research

Kaiser's historical research focuses on intersections among modern natural sciences, geopolitics, and the history of higher education during the Cold War. His major historical publications include: * Drawing Theories Apart: The Dispersion of Feynman Diagrams in Postwar Physics (2005) - A study of how the American physicist

Richard Feynman Richard Phillips Feynman (; May 11, 1918 – February 15, 1988) was an American theoretical physicist. He is best known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics, the physics of t ...

’s idiosyncratic approach to high-energy physics entered the mainstream. Recipient of the Pfizer Award from the History of Science Society. * How the Hippies Saved Physics: Science, Counterculture, and the Quantum Revival (2011) - An exploration of how countercultural figures became some of the earliest physicists to focus on Bell’s theorem and

. Recipient of the Davis Prize from the History of Science Society and name “Book of the Year” by ''Physics World'' magazine. * Quantum Legacies: Dispatches from an Uncertain World (2020) - An examination of how physicists have grappled with the conceptual uncertainties of quantum theory amid larger political disruptions throughout the twentieth century. Highlighted as among the best books of the year by ''Physics Today'' and ''Physics World'' magazines. His MIT course o
"Einstein, Oppenheimer, Feynman: Physics in the Twentieth Century"
is available via

MIT OpenCourseWare MIT OpenCourseWare (MIT OCW) is an initiative of the Massachusetts Institute of Technology (MIT) to publish all of the educational materials from its undergraduate- and graduate-level courses online, freely and openly available to anyone, anywh ...

. In addition to his scholarly writing, Kaiser's work has appeared in ''

The New York Times ''The New York Times'' (''NYT'') is an American daily newspaper based in New York City. ''The New York Times'' covers domestic, national, and international news, and publishes opinion pieces, investigative reports, and reviews. As one of ...

'', the

New Yorker magazine ''The New Yorker'' is an American magazine featuring journalism, commentary, criticism, essays, fiction, satire, cartoons, and poetry. It was founded on February 21, 1925, by Harold Ross and his wife Jane Grant, a reporter for ''The New York ...

, and in several

PBS Nova ''Nova'' (stylized as ''NOVΛ'') is an American popular science television program produced by WGBH in Boston, Massachusetts, since 1974. It is broadcast on PBS in the United States, and in more than 100 other countries. The program has won man ...

television programs. He also serves as Chair of the Editorial Board of the

MIT Press The MIT Press is the university press of the Massachusetts Institute of Technology (MIT), a private research university in Cambridge, Massachusetts. The MIT Press publishes a number of academic journals and has been a pioneer in the Open Ac ...

and as Editor of th
MIT Case Studies Series on Social and Ethical Responsibilities of Computing
As an invited advisor to a

U.S. National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Natio ...

panel during 2023-24, Kaiser helped to draft a consensus statement regarding generative artificial intelligence and scientific integrity, as well as providing historical context for societal reactions to previous once-new technologies.

Awards and honors

* LeRoy Apker Award,

(1993) * Pfizer Prize,

(2007) *

Fellow A fellow is a title and form of address for distinguished, learned, or skilled individuals in academia, medicine, research, and industry. The exact meaning of the term differs in each field. In learned society, learned or professional society, p ...

, American Physical Society (2010) * Davis Prize, History of Science Society (2013)

Books

*(2005)
''Drawing Theories Apart: The Dispersion of Feynman Diagrams in Postwar Physics''
University of Chicago Press. *(2005). (ed.
''Pedagogy and the Practice of Science: Historical and Contemporary Perspectives''
MIT Press. *(2010). (ed.
''Becoming MIT: Moments of Decision''
MIT Press. *(2011)
''How the Hippies Saved Physics: Science, Counterculture, and the Quantum Revival''
W. W. Norton, . *with Sally Gregory Kohlstedt: (2013). (eds.

University of Chicago Press. *with W. Patrick McCray: (2016). (eds.
''Groovy Science: Knowledge, Innovation, and American Counterculture''
University of Chicago Press. *(2020)
''Quantum Legacies: Dispatches from an Uncertain World''
University of Chicago Press. *with Aaron S. Wright and Diana Coleman: (2022). (eds.
''Theoretical Physics in Your Face: Selected Correspondence of Sidney Coleman''
World Scientific. *(2022). (ed.
'' 'Well, Doc, You're In': Freeman Dyson's Journey through the Universe''
MIT Press.