Dark energy

Interview with Katherine Freese, Director of the Weinberg Institute for Theoretical Physics, the Jeff and Gail Kodosky Endowed Chair in Physics at UT Austin, and the Director of the Texas Center for Cosmology and Astroparticle Physics (TCCAP). Freese begins the interview with an overview of terminology, such as cosmology, astrophysics, and astroparticle physics and the delineation between these fields. Then she describes her childhood in Bethesda, Maryland where both her parents were scientists. Freese recalls beginning college at age 16, starting at MIT and then transferring to Princeton. She recounts taking time off after her undergraduate studies, before deciding to pursue graduate studies. Freese began grad school at Columbia but switched to the University of Chicago to work on neutrino physics with David Schramm. She discusses her first post-doc at Harvard, working on WIMPs and dark matter, and then her second post-doc at Santa Barbara with Frank Wilczek. Freese then recalls returning to MIT as a professor where she worked with Alan Guth and Josh Frieman on cosmic inflation. She talks about her transition to the University of Michigan and the exciting developments in cosmology at the time, as well as her introduction to dark energy. Freese describes her more recent involvement with NASA’s SPIDER experiment, as well as the honor of being named to the National Academy of Sciences. Freese discusses the amazing opportunity of being the Director at the Nordic Institute for Theoretical Physics and ends the interview with her hopes for the future of cosmology, namely her hope for finding dark matter.

In this interview, Saul Perlmutter, Professor of Physics at UC Berkeley and Staff Scientist and senior faculty member at Lawrence Berkeley National Laboratory, discusses his life and career. Perlmutter shares that his research has not been slowed down by the pandemic by happy coincidence that he is currently focused on remote data analysis, and he recounts his childhood in Philadelphia where he was educated in Quaker schools. He discusses his early fascination with quantum mechanics and his decision to go to Harvard for his undergraduate education, where he cemented his interests in experimental physics. Perlmutter explains his decision to go to Berkeley for graduate school, where he worked in Buford Price’s group before Richard Muller became his graduate advisor. He discusses his early awareness of the cosmic microwave background and how he became involved with robotic searches for supernovae. Perlmutter describes the importance of NASA’s BITNET program as a way to connect observatory data worldwide to the computer systems at Berkeley, and he explains the intellectual and observational connections between the inflation, expansion, and acceleration of the universe. He discusses his postdoctoral research at Berkeley, and the circumstances leading to him becoming leader of the supernova group and how the DOE became more involved in astrophysics funding. Perlmutter explains the group’s focus on deceleration and he conveys the difficulties in scheduling telescope time to demonstrate spectroscopy proof of type Ia supernovae. He describes the origins of the SNAP satellite project, some of the early theoretical discussions on the nature of dark energy, and when, finally, his group secured long-term support from the Lab. Perlmutter narrates his first interactions with Brian Schmidt and Adam Riess and he describes the batch technique that could predict the discovery of supernovae, which vastly improved the efficiency of scheduling time on large telescopes. He explains the role of dark matter in speeding up the universe’s expansion, and he narrates the celebration with his team when he won the Nobel Prize and how he has chosen the use the political platform that comes with this recognition. Perlmutter discusses his interest in studying climate change, and at the end of the interview, he conveys his excitement about future observational discovery in astrophysics and cosmology.

Interview with Brian Schmidt, Distinguished Professor and Vice Chancellor and President of the Australian National University. Schmidt surveys the Covid crisis from his perspective at ANU, and he describes his current interests in cosmology. He recounts his childhood in Montana and Alaska in support of his father’s career in fisheries biology, and he describes his undergraduate education as a dual major in physics and astronomy at the University of Arizona. Schmidt describes the opportunities that led to his graduate work at Harvard, where he worked under the direction of Bob Kirshner and where he met and developed a formative relationship with Adam Riess on supernovae research. He explains his decision to remain at Harvard for his postdoctoral research and he narrates the origins of the High-Z collaboration and its interactions with Saul Perlmutter’s team at Berkeley. Schmidt describes his postdoctoral appointment at ANU as leader of High-Z, and he describes how the collaboration discovered the accelerating expansion of the universe and the process of communicating its findings. He describes the “buzz” leading to the Nobel Prize and his subsequent focus on the SkyMapper project. Schmidt discusses his responsibilities as Vice Chancellor which overlap strongly with Australian national policy, and he describes how he sees the reality of climate change in his 21 years of grape growing. At the end of the interview, Schmidt reflects on how the High-Z discovery has changed astronomy broadly, and he conveys a sense of wonder at the accidental nature by which the team arrived at its discovery.

In this interview, Robert P. Kirshner, Clowes Research Professor of Science at Harvard University, discusses his interests in supernovae and work as Chief Program Officer for Science at the Gordon and Betty Moore Foundation. He reflects upon the shifting terminology pertaining to astronomy, astrophysics and cosmology. He discusses his experience as an undergraduate at Harvard University. Kirshner details his experience at Caltech as a graduate student and his time studying supernovae under Bev Oke. He discusses his post-doc position at Kitt Peak National Observatory and the competition they had with Palomar. Kirshner speaks about his experience working with undergraduate students at the University of Michigan and eventually becoming the chair and observatory director. He details his role as head of Optical Infrared at the Harvard Smithsonian Center. Lastly, Kirshner discusses his Nobel Prize winning discovery of using observations of distant supernovae to discover the accelerating universe.

Interview with Joel Primack, Distinguished Professor of Physics Emeritus at the University of California, Santa Cruz. Primack discusses what he has been able to do in his free time since his retirement, including writing papers, giving lectures, hosting meetings at UC Santa Cruz, leading international collaborations, and supervising research. He sees the new data coming from the Vera Rubin Observatory and the Gaia Survey as exciting developments in the realm of astrophysics, and he is looking forward to adding to this data when we begin receiving images from the James Webb Space Telescope. Primack discusses his work with various simulations that he has utilized to understand what may be occurring within galaxies, and the growing importance of astrobiology in these simulations. He takes us back into his early years in Montana, where his passion for science began to develop, and how his high school education and internships led him to Princeton University for his undergraduate career. While at Princeton, Primack took classes from John Wheeler, worked at the Jet Propulsion Lab under Bill Pickering, and participated in the Students for a Democratic Society, where his interest in the combination of politics and science began to grow. Primack discusses how important the communication between politicians and scientists is, and he saw this need for improved communication early on. He started the Congressional Science and Technology Fellowship program as a preliminary way to work on the relationship between government and science. He then recounts his experiences at Harvard University and his eventual move to Santa Cruz, where he continued working on dark matter and dark energy, among other things. He remarks on his relationship and work with Nancy Abrams, including the courses they taught and the books they wrote together. He ends the interview talking about his family, his recovery from cancer, and the people he’s looking forward to working with in the future.

Interview with William H. Press, Leslie Suringer Professor in Computer Science and Integrative Biology at the University of Texas at Austin. Press recounts his childhood in Pasadena and the influence of his father Frank Press, who was a prominent geophysicist, Caltech professor, and who would become science advisor to President Jimmy Carter. He describes the impact of Sputnik on his budding interests in science, and he discusses his undergraduate experience at Harvard, where Dan Kleppner, Norman Ramsey, Ed Purcell and Dick McCray were influential in his development, and where he realized he had an aptitude for applying abstract equations to understanding physical reality. Press describes trying his hand with experimentation in Gerald Holton’s high-pressure physics lab, he recounts his involvement in student activism in the late 1960s, and he discusses his involvement in computer hacking in its earliest form. He explains his decision to attend Caltech for graduate school and his interest in studying with Dick Feynman and Kip Thorne. Press describes the opportunity leading to his work at Lawrence Livermore, how he got involved with Thorne’s group of mathematical general relativists, the origins of Thorne’s work on gravitational waves, and his collaborations with Saul Teukolsky and Paul Schechter. He describes the formative influence of Chandrasekhar. Press discusses his first faculty position at Princeton where he joined John Wheeler’s relativity group, and he describes his research interests flowing more toward astrophysics. He explains the opportunities leading to his tenure at Harvard, where he was given separate appointments in physics and astronomy and where he founded theoretical astrophysics within the Center for Astrophysics. Press describes his entrée into science policy work in Washington with the NSF Physics Advisory Committee and then later on the National Academy of Science and the National Research Council, and he explains the origins of his long-term association with the JASON Study Group. He describes his interest in gravitational collapse, Ia supernovae and galaxy formation, and why the study of black holes reinvigorated the field of general relativity. Press describes the singular genius of Freeman Dyson, and he recounts his contributions to nuclear risk reduction in science policy and his service with the Defense Science Board and the Institute for Defense Analyses. He discusses his tenure as chair in Harvard’s Department of Astronomy, his experience with the Numerical Recipes books, and his collaboration with Adam Riess and Robert Kirshner. Press recounts his decision take a position at Los Alamos as Deputy Director to John Browne, he describes his education there in the concept of leadership which he never received in his academic career, and he provides his perspective on the Wen Ho Lee spy case and the existential crisis this caused at the Lab. He describes the Lab’s role in the early days of computational biology and how this field sparked his interest. Press contextualizes this interest within his conscious decision not to stay connected to astrophysics during his time at Los Alamos, and he explains the opportunity leading to him joining UT-Austin where he remains invested in computational biology. He describes his work for the President’s Council of Advisors in Science and Technology during the Obama administration, he describes Obama’s unique interest in science and science policy, and he narrates the difficulties in the transition to the Trump administration. Press reflects on what it means to be a member of the rarified group of scientists who did not win a Nobel Prize but who were advised by and taught scientists who did. At the end of the interview, Press explains that he has always been a dilettante, which has and will continue to inform how he devotes his time to science, service, and policy matter, and he advises young scientists to aspire to mastery in a specific discipline early in their career before branching out to new pursuits.

Interview with Mark Trodden, Fay R. and Eugene L. Langberg Professor of Physics, and Co-Director of the Center for Particle Cosmology at the University of Pennsylvania. Trodden describes the overlap between astronomy, astrophysics, and cosmology, and he recounts his working-class upbringing in England. He discusses his undergraduate education at Cambridge, where he focused on mathematics, and he explains his decision to switch to physics for graduate school at Brown, where he worked under the direction of Robert Brandenberger. Trodden describes the impact of the COBE program during this time, and he discusses his work on the microphysics of cosmic strings and topological defects and their effect on baryon asymmetry. He explains his decision to return to Cambridge for his postdoctoral research with Anne Davis and his subsequent postdoctoral appointment at MIT to work with Alan Guth. Trodden discusses his next postdoctoral position at Case Western, which he describes as a tremendously productive period, and he discusses the opportunities that led to his first faculty position at Syracuse. He notes the excellent graduate students he worked with at Syracuse, and he explains what is known and not known with regard to the discovery of the accelerating universe. Trodden describes why the theory of cosmic inflation remains outside the bounds of experimental verification, and he explains the decisions that led to his decision to join the faculty at Penn and his subsequent appointment as chair of the department. He discusses the work that Penn Physics, and STEM in general, needs to do to make diversity and inclusivity more of a top-line agenda, and he describes much of the exciting work his current and former graduate students are involved in. At the end of the interview, Trodden looks to the future and offers ideas on how physicists may ultimately come to understand dark energy and dark matter.

Interview with Andrei Linde, Harald Trap Friis Professor of Physics at Stanford. This discussion continues from the interview with Linde conducted by Alan Lightman in October 1987. He provides a detailed history on his improvement of Alan Guth’s work on inflation, which Linde dubbed “new inflation” and subsequently “chaotic inflation.” Linde describes the impact of Perestroika on Soviet scientists, and the pressures he felt in preparing for a series of talks in Italy, which contributed to his development of “eternal inflation.” He discusses his formative early communication with American physicists including Lenny Susskind and Norman Coleman, he describes his two-year visit at CERN as the Cold War was winding down, and he explains his decision to accept a faculty appointment at Stanford. Linde describes the alternating feelings of hope and despair in the 1980s regarding the possibility that inflation could be observationally verified. He explains the intellectual origins of self-generating fractals that sprout other inflationary universes and the value of compactification theory, and he explains the cultural relevance of his Russian heritage which compels him to value theoretical notions and not treat them in a throwaway manner that capitalism can encourage. Linde explains how and why multiverses can be testable and he reflects on the obvious philosophical or even spiritual implications of this proposition. He discusses the impact of the discovery of the accelerating universe and dark energy and how WMAP strained the theoretical viability of inflation. Linde explains why many string theorists have moved into investigating theories of quantum information, and at the end of the interview, he reflects on the value of competing theories to inflation and why, ultimately, he wants to see a major convergence of theories so that the origins of the universe are well understood. 

Interview with Marcelle Soares-Santos, assistant professor of physics at the University of Michigan. Soares-Santos recounts her childhood in Brazil, her early interests in science, and her graduate work in physics at the University of São Paulo. She describes her graduate visit to Fermilab to study galaxy clusters as a way to map the history of the expanding universe, which formed the basis of her thesis research. Soares-Santos discusses her return to Fermilab as a postdoctoral researcher, where she joined the Dark Energy Survey, and she explains how DES is getting us closer to understanding what dark energy is. She describes Fermilab’s broad-scale transition into astrophysics, and she explains the opportunities that led to her faculty appointment first at Brandeis before moving to Michigan. Soares-Santos discusses her current work in gravitational waves, and she prognosticates on what the discovery of dark energy (or energies) will look like. She shares her perspective on recent efforts to improve diversity and inclusivity in STEM. At the end of the interview, Soares-Santos explains why observation is leading theory in the current work of astrophysics and cosmology and why she is optimistic for fundamental advances in the field.

Interview with Joshua Frieman, head of the Particle Physics Division at Fermilab, and professor of astronomy and astrophysics at the Kavli Institute for Cosmological Physics at the University of Chicago. He recounts his childhood in Princeton as the son of a physicist and his decision to attend Stanford as an undergraduate, where his interests in cosmology developed. Frieman explains that his options for graduate research in cosmology were narrow and his reasons for going to the University of Washington to work with Jim Bardeen before moving to Chicago to be Michael Turner’s first graduate student. He discusses his interest in approaching cosmology from the perspective of particle theory and his thesis focus on curved space time within a cosmological context. Frieman describes his postdoctoral work at SLAC and his first position at Fermilab in the theory group that Dave Schramm had started. He discusses his work on the Sloan Digital Sky Survey and then the Dark Energy Survey. Frieman explains what might be needed to understand dark energy, he describes his appointment at Chicago, and he explains the origins of the Magellan Telescopes project. He discusses the value of the Aspen summer sessions and his involvement with P5, and explains the value of the 2010 Decadal Survey. At the end of the interview, Frieman surveys the current slate of project at Fermilab and emphasizes the value of incorporating cosmological perspectives to high-energy and particle physics.