Observing the Invisible: A Collaborative Investigation between Astrophysicists and Philosophers

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

General Audience Summary This project is a collaborative investigation between astrophysicists and philosophers of science that focuses on the astrophysical notion of dark matter, which does not produce or interact with light (or, more broadly, electromagnetic radiation). Astrophysicists believe that twenty-five percent of the universe is composed of dark matter, but they don't know what dark matter is or where most of it resides. The guiding empirical hypothesis of this project is that some dark matter resides in dark galaxies; that is to say, in dark matter halos that either never possessed or have lost their ordinary matter at some time in the past. The project involves searching for these dark galaxies and studying the unique blend of observation, simulation, theory, and reasoning that allows astrophysicists to make such a discovery. It will provide a unique opportunity for a postdoctoral fellow to receive advanced training in philosophy and astrophysics at the highest levels; it is designed to fully engage the post-doctoral fellow in astrophysical work at the telescopes and with computers. In addition, astrophysicists will participate in a philosophical analysis of the scientific study. It is hoped that this intimate and intense interaction will push the boundaries of knowledge in astrophysics and at the same time demonstrate the unique richness inherent in a new sub-discipline, philosophy of astrophysics. The postdoc will spend three terms at the University of Pennsylvania, one term at the Carnegie Observatories, and she will be trained to use the Magellan telescopes at Las Campanas. The researchers will train and be assisted by undergraduate research assistants, who are to be recruited in part from programs targeting students from under-represented groups. Researchers on the project will give four public lectures on topics in the philosophy of astrophysics. In addition, the postdoc will develop a K-12 outreach kit that focuses on exciting topics in dark matter galaxy research and important new roles for citizen scientists. Technical Summary This interdisciplinary project focuses on the search for dark matter galaxies by bringing into joint consideration the simulations, observations, and database-combing required to find them, and the philosophical issues raised and illuminated by the search. The central philosophical issues are focused on the theme of epistemic warrant. For example, they will consider how imaging, spectroscopy, simulation, and theorizing combine to warrant inferences about objects that are millions of light-years away and are intrinsically invisible at all known frequencies. Another example is the use of simulations of dark-matter-galaxy/luminous-matter-galaxy interactions to determine their behavior. This will provide an opportunity to study the precise ways that theory enters into the construction of simulations, and how much theory determines values for simulation parameters. Philosophical questions include: What warrants importing these data into the luminous/dark-galaxy interactions? What considerations go into concluding simulations are precise and accurate, given that no one has ever knowingly observed the target event?