Philosophy of Physics Seminar (Thursday - Week 3, MT25)

Abstract: Decay has been a quintessentially quantum process since its discovery at the end of the 19th century. It has also been placed at the heart of quantum foundational problems, such as the mechanism in the original Schrödinger cat paper. From this, it has been common to connect decay to the measurement problem. Here, I outline different mathematical theories describing decay to identify key features. Many such models involve idealisations or approximations that mean the entire process cannot be adequately modelled. By exploring further the notion of incompleteness in the measurement problem, it is suggested that decay presents an additional aspect of quantum incompleteness, over and above the concerns about measurements. This is done by trying to distinguish different notions of incompleteness within quantum physics. In particular, the role time and dynamics play in decay processes, lead to an extended notion in these cases. This does not remove the problem of measurement but reinforces the current limitations of our quantum understanding.