Why is quantum measurement so puzzling? | Puzzling Science with Maria Violaris

Quantum mechanics is one of the most successful theories in physics... but what actually happens when we measure a quantum system? Quantum physicist Maria Violaris explores the measurement problem: one of the biggest questions and controversies in quantum mechanics. Starting with Schrödinger's famous cat, Maria explains how superposition and entanglement lead to a fundamental puzzle: if quantum systems can exist in multiple states, why do we only ever observe one outcome? Maria explores the competing ideas that try to explain what happens during measurement, including collapse theories, the Copenhagen interpretation and the many-worlds interpretation. She then introduces Wigner's friend, a thought experiment that takes the measurement problem even further and shows how it could, in principle, help distinguish between different theories of quantum mechanics. The story also leads to the origins of quantum computing, and finally to Maria's own idea about whether information could somehow be exchanged between different branches of a quantum multiverse. So, does measurement really cause a quantum system to collapse — or are all the possible outcomes real? __________ Chapters: 00:00 What is the measurement problem? 00:42 Schrödinger's cat 02:15 Many worlds or collapse? 03:21 The measurement postulate 05:03 Different theories of quantum mechanics 06:01 The many-worlds interpretation 08:15 Wigner's friend 12:10 Can we test the measurement problem? 14:43 The origins of quantum computing 16:25 Can quantum worlds communicate? 19:59 A new test for many worlds? __________ 🧩Subscribe to the Royal Institution for more science, mathematics and technology. We post a new epsiode of Puzzling Science every month! http://bit.ly/RiSubscRibe 🧩 __________ Maria Violaris is a quantum physicist and prize-winning science communicator with a PhD in the foundations of quantum information from the University of Oxford. She works on quantum theory research at Oxford Quantum Circuits, runs a YouTube channel and the Quantum Foundations Podcast, and pioneered the use of quantum thought experiments for quantum computing education through her Quantum Paradoxes series at IBM Quantum. ___________ 🧩 Puzzling Science is a series where a different scientist tackles a jigsaw puzzle while walking us through their specialist subject — one piece, and one idea, at a time. We upload a new Puzzling Science episode every month, featuring a different scientist and a different field 🧩 ___________