QSE Center's Quantum Seminar: Andreas Albrecht

For the first QSE Center Quantum Seminar of the Autumn 2023 semester, Prof. Andreas Albrecht from the University of California, Davis will speak on Wednedsay, September 20, about the "Origin of probabilities and their application to the multiverse". Location: CE 1 106

Pizzas will be available before the seminar at 12:30. All PhDs, postdocs, students, and PIs are welcome to join us.

TITLE:
Origin of probabilities and their application to the multiverse
 
ABSTRACT:
I argue using simple examples (such as the coin flip) that all successful practical uses of probabilities connect to physical randomness originating from quantum fluctuations in the microscopic physical world around us, often propagated to macroscopic scales. Thus I claim there is no physically verified fully classical theory of probability.  And I argue that while the “principle of indifference” often offers a great phenomenology of the physical world, it has no fundamental basis in pure theory. I comment on the general implications of this view, and specifically question the application of classical probability theory to cosmology in cases where key questions are known to have no quantum answer.  Overall, this approach offers a certain disciplined perspective on probabilities in physical theories which may yield progress on the notorious measure problems associated with eternal inflation.
Based on this paper

BIO:
Andreas Albrecht is a leading theoretical cosmologist. He received his PhD from the University of Pennsylvania in 1983 where, with Paul Steinhardt, he wrote one of the original papers on “new” or “slow roll” inflation. Slow roll inflation has since become the dominant phenomenological theory of the early Universe and has passed numerous observational tests with flying colors. Deep puzzles remain regarding the theoretical underpinnings of cosmic inflation and Albrecht is a leading figure in this research area. Albrecht's work in the 1990's on observational signatures allowed modern data to rule out a broad category of “active” theories of cosmic structure in favor of the “passive” category (to which inflation belongs).
The discovery of cosmic acceleration (celebrated by the 2011 Nobel Prize in Physics and often referred to as “the dark energy”) has been transformative to the field of cosmology. Albrecht is known for his groundbreaking work on dark energy theory and phenomenology, including key contributions on the Dark Energy Task force and related work to determine the best observational probes of cosmic acceleration.
Albrecht is well-known for pioneering work on the arrow of time, the clock ambiguity and the origin of probabilities, all topics that figure prominently in the current search for a more complete theory of the cosmos.
Albrecht moved from a Professorship at Imperial College to UC Davis in 1998 to build the cosmology program there. He served as Physics Department Chair 2011-2016, and in 2017 he was named inaugural director of the Center for Quantum Mathematics and Physics (QMAP). He is a Fellow of the American Academy of Arts and Sciences, the American Physical Society, the Institute of Physics and the American Association for the Advancement of Science. His ongoing research program embraces a wide range of challenges posed by our search for a deeper understanding of the Universe.