PSA2018 President’s Plenary Symposium

 Shedding Light on Dark Matter

Concepts and Challenges from the Frontiers of Astrophysics

4:00 - 5:45 pm

1 November 2018

Metropolitan Ballroom B, Sheraton Seattle Hotel


It is a number hard to accept: more than 3/4 of the matter in the Universe is in a form whose basic nature we know virtually nothing about except for one crucial fact: it interacts gravitationally with normal, visible (baryonic) matter, the stuff that planets, stars and galaxies are made of. Moreover, by all estimations this previously unknown form of matter has dominated the formation and evolution of structure in our Universe from the earliest moments of creation up to and including the present day. And yet, despite decades of observational and theoretical research, the physical nature of this “dark matter” still remains shrouded in mystery. And this mystery is now precipitating measured amounts of controversy and concern. Together with its no-less-mysterious sibling, “dark energy”, the central role of dark matter in our concordance (ΛCDM) cosmological model, has led to repeated declarations that cosmology and/or particle physics is in a state of crisis.

This symposium will focus on the historical origins of the concept and present wide-ranging observational evidence in favor of the existence of dark matter throughout the universe. We will enumerate the possible particle-physics candidates for dark matter, and touch upon the experimental strategies being used to explore them. We will also present the most recent observational results bearing on dark matter. The introduction of dark matter into astrophysics has fundamentally changed the way we conceptually and practically model and explore the cosmos on both the smallest and on the largest scales. Particle physics and astrophysics now meaningfully interface with each other in a cosmological setting, mutually addressing questions of a truly fundamental nature. Given that dark matter was not predicted by any pre-existing theories of matter in the Universe, and given that there has not yet been a successful detection of any the theoretical entities put forward as candidates for dark matter candidates, this has led some to suggest the alternative possibility that the laws of gravity might need to be reconsidered and modified.

Faced with the enigma dark matter, as one of the outstanding unsolved problems in modern cosmology, there is clearly ample opportunity for philosophical reflection. This symposium aims at both providing a starting point for that reflection, and offering an invitation to both philosophers and astrophysicists to mutually engage in that dialogue.


Barry Madore                      Sabylle Anderl

Barry Madore
is a Senior Research Astronomer at the Observatories of the Carnegie Institution of Science, based in Pasadena, California.  He did his graduate work at the University of Toronto, followed by postdoctoral research in Cambridge, England. Returning to Canada he rose to the rank of Full Professor at U of T before moving to Caltech, where he founded the NASA/IPAC Extragalactic Database which currently serves over 10 million requests per month for information on all known extragalactic objects.  He is currently jointly affiliated with Caltech, JPL, Carnegie and the University of Chicago. His immediate areas of expertise include observational cosmology and the astrophysics of star formation in the context of galaxy formation and evolution.  For the past 30 years he and his wife, Prof. Wendy Freedman (Univ. Chicago) have been leading a program to determined the age and size of the Universe using ground-based telescopes in Chile & Hawaii, and space-based telescopes such as NASA’s Hubble Space Telescope (HST) and the SPITZER infrared space telescope.  Most recently he and Michael Weisberg (Chair of the Philosophy of Science Dept, U. Penn) have joined forces with two postdocs (Marja Seidel at Caltech and Melissa Jacquart at U. Penn) to undertake a coordinated and philosophically-informed observational search  for pure dark-matter galaxies. Barry personally believes that doing astrophysics is a form of applied philosophy of science, and feels that both philosophers of science and astrophysicists would mutually profit from closer collaborations and stronger professional ties.  He is trying to lead by example.

Dr. Sibylle Anderl obtained a double-degree in physics (Diplom) and philosophy (Magister) at the Technische Universität Berlin, Germany. In 2013 she received her Ph.D. in Astronomy/Astrophysics from the Rheinische Friedrich-Wilhelms-Universität Bonn. Her Ph.D. project focused on the modelling and observation of shock waves in the interstellar medium. After completion of her degree she joined the Institut de Planétologie et d’Astrophysique in Grenoble, France, as a postdoctoral researcher to work on problems in star formation and astrochemistry. Since 2017 she is a visiting scientist at this institute. Besides her research in astrophysics, she has worked on topics in the philosophy of science. Since 2010 she has been working as a freelancer science writer for the German national daily newspaper “Frankfurter Allgemeine Zeitung” and is a permanent full-time member of the science desk since 2017. In 2017 her first popular science book on the generation of astrophysical knowledge was published.



Sandra Mitchell      Chris Smeenk      James Weatherall

Sandra D. Mitchell is President of the PSA and Distinguished Professor of History and Philosophy of Science at the University of Pittsburgh. Her work has focused on scientific explanations of complex behaviors from socialinsect dynamics, to psychiatric genetics to protein folding. She is a AAAS Fellow. Her books include Unsimple Truths: Science, Complexity and Policy (2009 University of Chicago Press) and Biological Complexity and Integrative Pluralism (2003 University of Cambridge Press).

Chris Smeenk is Associate Professor in the Department of Philosophy at Western University, and Director of the Rotman Institute of Philosophy. He received a B.A. degree in Physics and Philosophy from Yale University in 1995, and pursued graduate studies at the University of Pittsburgh leading to a PhD. in History and Philosophy of Science in 2003. He has held a post-doctoral fellowship at the Dibner Institute for History of Science and Technology (MIT) and was an assistant professor in the Department of Philosophy at UCLA (2003-2007).

James Owen Weatherall is Professor of Logic and Philosophy of Science at the University of California, Irvine, where he is also a member of the Center for Cosmology and the Institute for Mathematical Behavioral Science.  He is the author, most recently, of The Misinformation Age: How False Beliefs Spread, with Cailin O'Connor, which will be published by Yale University Press in January 2019; his previous books were the The Physics of Wall Street (Houghton Mifflin Harcourt, 2013) and Void: The Strange Physics of Nothing (Yale, 2016).  He has published on a range of topics in in physics, philosophy, and mathematics, but most of his research has concerned the mathematical and conceptual foundations of classical field theories, including general relativity.  Along with Chris Smeenk, he was recently awarded a grant by the John Templeton Foundation to support work on philosophical issues related to cosmology.

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