Philosophical Society of Washington

The Universe You Don't See: The Existence and Nature of Dark Matter

Virginia L. Trimble
University of Maryland

2000th Meeting Abstract
Friday, October 23, 1992 at 8:15 PM


A wide range of astronomical observations demonstrate that 90% or more of the mass that contributes to the gravitational forces in the universe does not emit its fair share of light. This rises to 99% if one assumes that the total density is sufficient to reverse the expansion of the universe in the distant future. The nature of this dark matter is exceedingly uncertain. Calculations of nuclear reaction rates in the early dense state ("Big Bang") strongly limit the amount of ordinary matter (made of atoms with nuclei of protons and neutrons) to about 10% of the closure density. A very wide range of alternatives has been suggested. and laboratory experiments may eventually distinguish among them.

About the Author:

Ms. Trimble received her PhD in Astronomy from the California Institute of Technology in 1968. Her research has encompassed many topics of astrophysics such as binary stars, open clusters, supernova remnants, and dark matter. Throughout her career, she has served on the boards of various professional societies including the American Physical Society and the American Association for the Advancement of Science as well as on the editorial boards of various scientific journals. She is currently a Professor at the University of California, Irvine, a Visiting Professor at the University of Maryland, and an editor or editorial board member of six journals including "The Scientist" and "Astrophysical Journal".

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