NemoClaw Knowledge Wiki

New Experimental Evidence for Feynman's All Paths Quantum Reality

4 min read

🗂️ Science, Physics & Research · View mindmap

New Experimental Evidence for Feynman’s All Paths Quantum Reality

Clip title: FINALLY: A Proof that Particles Take All Paths At Once? Author / channel: Sabine Hossenfelder URL: https://www.youtube.com/watch?v=A2ImadKWaHA

Summary

This video by Sabine Hossenfelder delves into a recent claim by a team of physicists in China regarding Richard Feynman’s path integral formulation of quantum mechanics. For 80 years, Feynman’s interpretation has suggested that quantum particles take every possible path simultaneously when traveling between two points. While this mathematical framework is known to accurately predict experimental outcomes, the question of whether this “all paths at once” is a physical reality or merely a computational tool has remained a subject of intense debate among physicists.

The core of Feynman’s path integral is that instead of a single, deterministic trajectory like in classical physics, a quantum particle’s probability of being at a certain location is derived by summing the “amplitudes” of every conceivable path it could take. This mathematical elegance provides a visual understanding of quantum phenomena, but critically, it also implies that observing the particle mid-path would collapse its wave function, forcing it onto a single, observable trajectory. Therefore, directly proving the “physical reality” of all paths has been inherently challenging due to the measurement problem in quantum mechanics.

The new paper by Wen et al. (Sci Adv 12, 2026) claims to provide experimental evidence that these paths are “more than mere mathematical artifacts—they reflect a physical aspect of quantum reality.” Their experiment involved sending single photons through a grid of “weak measurement” points, designed to probe the photon’s amplitude between specific locations without fully collapsing its wave function. They found that these amplitudes indeed matched Feynman’s predictions, leading them to conclude they had validated his postulate and demonstrated the physical reality of multiple paths.

However, Sabine Hossenfelder critically disputes this interpretation. She argues that while the experiment beautifully confirms the accuracy of Feynman’s mathematical predictions (which were never doubted), it does not prove that particles physically traverse all paths when unobserved. The weak measurements, by definition, are still observations. The experiment simply shows that if you measure the photon at various points along its journey using weak interactions, the sum of these weak measurements aligns with the path integral’s probabilistic outcomes. It fails to answer the fundamental question posed by figures like Albert Einstein and John Bell: does a quantum particle truly exist in a superposition of paths when not being measured, or does it only take one path, even if we don’t know which one until observed? The debate on the physical interpretation of quantum mechanics, therefore, remains unsettled.

Video Description & Links

Description

Eighty years ago Richard Feynman said that a quantum particle takes every possible path at the same time. A team of physicists in China now says they have experimentally shown this is not just an interpretation but physical reality, and the headlines duly followed. I had a look at what they actually measured.

Paper: DOI: 10.1126/sciadv.aeh1011

science sciencenews physics quantumphysics

👕T-shirts, mugs, posters and more: ➜ https://sabines-store.dashery.com/ 💌 Support me on Donorbox ➜ https://donorbox.org/swtg 📝 Transcripts and written news on Substack ➜ https://sciencewtg.substack.com/

Tags

hossenfelder, science with sabine, science humour, science news, physics news, Feynman path integral, sum over histories, quantum mechanics, quantum interpretation, Copenhagen interpretation, many worlds, pilot wave, hidden variables, double slit experiment, wave particle duality, quantum entanglement, Bell test, Bell inequality experiment, Science Advances, photonics, quantum optics, Feinman, Shrodinger, super determinism, sabrina

URLs

Graph View