After 100 Years of Quantum Mechanics: Toward a Constructive Observation-Centered Perspective

TL;DR

This paper advocates for a new constructive, observation-centered framework in quantum mechanics, emphasizing signals as primary objects and connecting spectral analysis with finite observation limitations.

Contribution

It introduces a signal-based spectral equation approach, linking quantum formalism to practical finite observation constraints and effective descriptions.

Findings

Identifies a sharp accuracy transition related to observation time and spectral density.

Connects spectral analysis with finite observation time to quantum simulation.

Proposes a framework integrating approximation into quantum foundations.

Abstract

Quantum mechanics owes much of its extraordinary success to a Hilbertian program of mathematical formalization. Yet, the formalism remains poorly aligned with the practical limitations of computations in finite dimensions and under finite accuracy. In this perspective, we argue that this mismatch points to the need for a new mathematical program: a rigorous constructive theory for effective descriptions to identify essential degrees of freedom. We propose an observation-centered point of view in which signals are treated as the primary objects of analysis, while wave functions and Hamiltonians are reconstructed as auxiliary structures to rationalize the observed data. Our starting point is a signal-based spectral equation that reformulates frequency analysis as an operator problem. We connect this point of view to results on prolate Fourier theory, spectral analysis with finite observation time, and short-time quantum simulation. We highlight a sharp accuracy transition relating necessary observation time to the effective spectral density of a signal for achieving accurate resolution. The resulting framework integrates approximation as a fundamental necessity more directly into the foundations of quantum mechanics and points toward a broader program for the effective description of complex quantum systems, such as those found in the molecular sciences.