# What physics gets wrong about quantum | Jacob Barandes Source: https://www.youtube.com/watch?v=DF_5M7P8NNM Recap page: https://rapidrecap.app/video/DF_5M7P8NNM Generated: 2026-03-10T18:04:51.795+00:00 --- ## Quick Overview Physicist Jacob Barandes argues that the inherent probabilistic nature of quantum mechanics, as suggested by the Everett interpretation (Many-Worlds), provides a more elegant mathematical framework than the standard interpretation which relies on an arbitrary and physically undefined collapse postulate. **Key Points:** - The standard formulation of quantum mechanics, including the Dirac and von Neumann axioms, faces the measurement problem due to the undefined collapse postulate. - The Everett interpretation (Many-Worlds) avoids the collapse postulate by treating the quantum state as a purely mathematical entity evolving unitarily, thus removing the need to specify what constitutes a measurement or observer. - The Everett formulation is mathematically simpler and more elegant than the standard textbook quantum mechanics, which requires an arbitrary mechanism to lock in measurement results. - The Hamiltonian of the Everett formulation is derived from the kinetic and potential energy of the system, akin to classical mechanics, rather than relying on ad-hoc additions. - Barandes notes that while the Everett approach is mathematically elegant, its ontological commitment—the existence of many worlds—is difficult for many physicists to accept. - The Everett framework suggests that reality is fundamentally probabilistic, as the wave function evolves deterministically across a vast Hilbert space, but the observable outcomes are probabilistic based on the measurement process. - The speaker prefers the Everett approach because it replaces the ambiguous 'collapse' event with a mathematically clean, unitary evolution, even if the resulting ontology is counterintuitive. ![Screenshot at 00:04: Barandes begins discussing the core issue: whether the lack of a clear definition for measurement in quantum mechanics leads to unnecessary speculative metaphysics.](https://ss.rapidrecap.app/screens/DF_5M7P8NNM/00-00-04.jpg) **Context:** Jacob Barandes, a physicist, discusses the fundamental interpretive challenges within quantum mechanics, specifically focusing on the 'measurement problem'—the transition from the smooth, deterministic evolution of the wave function to a definite outcome upon measurement. He contrasts the standard Copenhagen interpretation, which requires an arbitrary 'collapse postulate,' with the Many-Worlds Interpretation (Everett interpretation), which attempts to derive the probabilistic nature of outcomes purely from unitary evolution within an abstract mathematical framework, like Hilbert space. ## Detailed Analysis Jacob Barandes argues that the measurement problem in quantum mechanics, stemming from the arbitrary nature of the collapse postulate in standard interpretations (like Copenhagen), suggests that alternative formulations are necessary. He favors the Everett interpretation (Many-Worlds) because it relies only on the unitary evolution of the wave function (a mathematical entity evolving in an abstract Hilbert space) without invoking a separate, physically undefined collapse mechanism. He explains that the Hamiltonian in the Everett approach is derived similarly to classical mechanics (kinetic minus potential energy), providing a smooth, mathematically elegant description. However, he acknowledges that this approach requires accepting an ontology where the quantum state itself is physical, and reality is fundamentally probabilistic rather than deterministic, which is difficult for many physicists. He contrasts this with the standard approach where the wave function is often treated as merely informational, and the probabilistic nature arises from the collapse postulate itself, which he finds less satisfying than the inherent probabilistic evolution derived from the Everett formalism. He concludes that while the Everett approach is mathematically elegant and potentially leads to fewer arbitrary assumptions, its metaphysical implications remain a point of contention. ### The Measurement Problem - The standard formulation (Dirac/von Neumann) is based on axioms that separate smooth evolution from the discontinuous collapse upon measurement - This forces physicists to struggle with defining what constitutes a measurement or an observer. ### The Everett Approach - Everett's interpretation avoids the collapse postulate entirely by treating the quantum state (wave function) as a mathematical entity evolving unitarily in a high-dimensional Hilbert space - This results in a deterministic evolution of the total state, even if observable outcomes remain probabilistic. ### Mathematical Elegance vs. Ontology - Barandes suggests the Everett approach is mathematically more elegant and simpler because it avoids ad-hoc rules like collapse, drawing inspiration from classical mechanics' Hamiltonian formulation - However, accepting this requires accepting the existence of many worlds (a complex ontology). ### The Role of Probability - In the Everett view, probability is fundamental, arising from the structure of the Hilbert space and how measurement projections work, rather than being imposed by an external collapse postulate. ### Historical Context - He references the work of John von Neumann (1932) and Hugh Everett (1956) in developing these differing views, noting that many early quantum physicists preferred the mathematical beauty of the wave function, even if they struggled with its physical meaning. ![Screenshot at 00:03: Barandes introduces the topic by referencing the interpretational mysteries of quantum theory.](https://ss.rapidrecap.app/screens/DF_5M7P8NNM/00-00-03.jpg) ![Screenshot at 00:13: Barandes gestures while posing the question about confronting the measurement problem without adding arbitrary axioms.](https://ss.rapidrecap.app/screens/DF_5M7P8NNM/00-00-13.jpg) ![Screenshot at 00:55: Barandes explains that the standard quantum mechanics formulation represents a 'break' from previous physical laws.](https://ss.rapidrecap.app/screens/DF_5M7P8NNM/00-00-55.jpg) ![Screenshot at 01:34: Barandes contrasts the standard approach with the mathematical formalism of the Everett interpretation, referencing Hilbert space.](https://ss.rapidrecap.app/screens/DF_5M7P8NNM/00-01-34.jpg)