ABSTRACT: The United Nations has declared 2025 as the International Year of Quantum Science and Technology, recognizing a century's worth of scientific effort in the broad field of 'quantum'.  However, despite enormous scientific progress, there is still an outstanding fundamental issue: the so-called "measurement problem".  In quantum mechanics, scientists learn that a quantum system evolves in time according to Schrödinger's equation.  This evolution is deterministic, with systems generally existing as a linear superposition of different system-states.  However, upon measurement, a system is always found to be in only one of these system-states, with the outcome given probabilistically by Born's rule.  This describes the heart of the measurement problem: after measurement, why does a deterministic superposition of many states always find itself in a singular state conditioned probabilistically?  

Thus far there has been no definite answer but many proposed solutions to the measurement problem, which are most commonly referred to as "interpretations" of quantum mechanics.  In this Mulligan Memorial Lecture, I will present a historical overview of the measurement problem, and how it became an odd subject between pure philosophy and quantum foundations which make it a challenging topic of discussion amongst modern scientists.  We will focus on the journey undertaken by several key physicists as they attempted to understand the implications of quantum mechanics on the nature of reality in the context of trying to 'solve' the measurement problem.