The Expanding Universe: What We Know and Don’t Know

The Steven Weinberg Memorial Lecturer Dr. James Peebles, winner of the 2019 Nobel Prize in Physics for his work on cosmological models, will discuss the lingering questions of our ever-growing universe. What was the Universe doing before it was expanding? What is the dark matter that dominates the mass of the Universe? Dr. Peebles will explore these questions and more!

Abstract

We have good evidence that the universe we see around us is not forever. The universe started expanding from a hot dense state known as the Big Bang. The universe still is expanding and cooling, leaving fossil evidence from what happened as the  universe expanded. These fossils are the evidence that our universe really is evolving. Yet the theory of the expanding universe is incomplete. I will explain what we know and do not know; so many questions remain. What was the Universe doing before it was expanding? What is the dark matter that dominates the mass of the Universe? Steven Weinberg's research on particle physics introduced the idea of dark matter, but we still do not fully understand its interplay with the Standard Model of Particle Theory that Weinberg did so much to establish. We are leaving fascinating problems for research by new generations of scientists.