Quantum mechanics requires Hilbert space — or so we have been told it must.
Students arrive at university and encounter the formalism as pedagogical gospel. Entering this infinite-dimensional abstract realm is not optional but necessary to understand what quantum things actually are. Without it, you remain outside looking in.
This language of necessity carries historical weight. In the 1920s, electrical engineers were solving AC circuit problems without complex numbers — they had real working methods, calculated power and impedance using trigonometry and geometry. Their designs worked. Then mathematicians and academic physicists began insisting that complex numbers were not just convenient but essential to truly understand alternating current.
Within a generation, complex numbers had become a credential requirement. You could build a circuit without them. You could not teach one, publish one, or advance in the field without demonstrating mastery of the abstraction. The gate was not that the mathematics was wrong. The gate was that it had been declared necessary for respectability rather than for solving the problem. Hilbert space arrived in quantum mechanics at precisely the moment when such arguments carried particular force, in the 1930s and 1950s, when abstraction itself had become a marker of intellectual seriousness.
The gate was that it had been declared necessary for respectability rather than for solving the problem.
What matters is not whether Hilbert space is useful for quantum calculations, it demonstrably is. What matters is what gets excluded by insisting that useful tools are actually necessary preconditions for thinking. Engineers, experimentalists. People outside the credentialing structure have repeatedly discovered that problems get solved by those who think differently than required. When you encounter any field declaring that a particular abstraction is not optional for "real understanding," ask who benefits when the gate stays locked and who loses when it opens.