Classical physics can explain quantum weirdness!

When you throw a ball in the air, the equations of classical physics will tell you exactly what path the ball will take as it falls, and when and where it will land. But if you were to squeeze that same ball down to the size of an atom or smaller, it would behave in ways beyond anything that classical physics can predict.

Scientists have now shown that certain mathematical ideas from everyday classical physics can be used to describe the often weird and nonintuitive behaviour that occurs at the quantum, subatomic scale.

In a paper appearing recently in the journal Proceedings of the Royal Society A Mathematical Physical and Engineering Science, the team shows that the motion of a quantum object can be calculated by applying an idea from classical physics known as "least action." With their new formulation, they show they can arrive at exactly the same solution as the Schrödinger equation—the main description of quantum mechanics—for a number of textbook quantum-mechanical scenarios, including the double-slit experiment and quantum tunnelling.

Such mysterious phenomena, that could only be understood through equations of quantum mechanics, can now also be described using the team's new classical formulation. In essence, the researchers have built an exact mathematical bridge between the classical, everyday physical world and the world that happens at dimensions smaller than an atom.

A reformulation of the classical Hamilton-Jacobi equation, incorporating density and multiple least-action paths, can exactly reproduce quantum phenomena such as the double-slit experiment, quantum tunneling, and hydrogen atom wave functions. This approach mathematically bridges classical and quantum mechanics, showing that quantum behaviour can be computed using classical principles without approximations.

This 2026 study has demonstrated that classical physics principles can explain quantum 'weirdness' behaviours, such as tunnelling and energy discretization, using a new mathematical approach. By applying classical models to super-conducting circuits, researchers showed that these behaviours are not fragile quirks, but rather robust, non-local, wave-like characteristics that can emerge in larger, complex systems, merging quantum intuition with classical, macroscopic reality.

Key details:
Bridge to Reality: The experiment bridges the gap between quantum mechanics and everyday intuition by showing quantum laws aren't just for microscopic particles.
Quantum Tunnelling Explained: What was previously thought to be impossible tunnelling in classical physics can now be described by these updated classical approaches.
Wave-Particle Duality: The studies demonstrate that quantum objects act as waves and particles simultaneously, passing through multiple paths, which can be interpreted within a sophisticated classical framework.
System Coherence: The study found that quantum weirdness depends on wave coherence (lining up), which can be analyzed using traditional wave dynamics.
Environment Interaction: Quantum information spreads into surrounding systems (quantum Darwinism) rather than remaining isolated, allowing for classical analysis.

This research, which heavily references the work of figures like Feynman and Schrödinger, argues that what has been considered "weird" in quantum mechanics is a matter of interpreting "wave-like behaviour" within our classical, logical understanding

Winfried Lohmiller et al, On computing quantum waves exactly from classical action, Proceedings of the Royal Society A Mathematical Physical and Engineering Science (2026). DOI: 10.1098/rspa.2025.0413