Fred Adams: The Degree of Fine-Tuning in our Universe—and Possibly Others

November 8, 6:00pm

Natural Sciences Building Auditorium, UC San Diego

Free and open to the public

Fred C. Adams, theoretical astrophysicist at the University of Michigan, joins us for an insightful talk about how life in this universe—and potentially others—is possible.

The fundamental constants of nature must fall within a range of values in order for the universe to develop structure and ultimately support life. This talk considers the current constraints on these quantities
and assesses the degree of fine-tuning required for the universe to be viable. The first step is to determine what parameters are allowed to vary. In the realm of particle physics, we must specify the strengths of the fundamental forces and the particle masses. The relevant cosmological parameters include the density of the universe, the cosmological constant, the abundance of ordinary matter, the dark matter contribution, and the amplitude of primordial density fluctuations. These quantities are constrained by the requirements that the universe lives for a sufficiently long time, emerges from its early epochs with an acceptable chemical composition, and can successfully produce galaxies. On smaller scales, stars and planets must be able to form and function. The stars must have sufficiently long lifetimes and hot surface temperatures. The planets must be large enough to maintain atmospheres, small enough to remain non-degenerate, and contain enough particles to support a biosphere. We also consider specific fine-tuning issues in stars, including the triple alpha reaction that produces carbon, the case of unstable deuterium, and the possibility of stable diprotons. For all of these issues, the goal of this enterprise is to delineate the range of parameter space for which universes can remain habitable.

Fred Adams works in the general area of theoretical astrophysics with a focus on the study of star formation and cosmology. He is internationally recognized for his work on the radiative signature of the star formation process, the dynamics of circumstellar disks, and the theory of the initial mass function for forming stars. His recent work includes star formation in clusters, studies of extra-solar planetary systems, and the environmental effects of clusters on planet formation. In cosmology, he has studied aspects of the inflationary universe, cosmological phase transitions, magnetic monopoles, cosmic rays, the cosmic background radiation, galactic halos of dark matter, and the long-term future of the universe.