While this article stipulates how this has been the case since 1930, I'd argue that it's been the case since early 19th century too (tbh, before checking, I tho

While this article stipulates how this has been the case since 1930, I'd argue that it's been the case since early 19th century too (tbh, before checking, I thought it was late 19th): https://en.m.wikipedia.org/wiki/Non-Euclidean_geometry#Discovery_of_non-Euclidean_geometry https://en.m.wikipedia.org/wiki/Non-Euclidean_geometry#Disco... : "Bolyai ends his work (from 1830) by mentioning that it is not possible to decide through mathematical reasoning alone if the geometry of the physical universe is Euclidean or non-Euclidean; this is a task for the physical sciences."