This study proposes a geometric solution to the proton radius puzzle based on the theory of a dense ether and Minkowski metrics. It is demonstrated that the discrepancy between the radius measured with the electron (0,875fm) and that measured with the muon (0,84fm) is not caused by experimental error, but by a real metric contraction induced by the mass of the probe particle. Through the radial differential identity dR/dR = 1, the Minkowski volume is derived as a relativistic invariant, explaining why the scattering angle remains unchanged despite the reduction in radius. Finally, MUSE experiment at PSI is identified as the "Michelson-Morley experiment of the 21st century", capable of detecting the variation in the muon’s velocity induced by the metric resistance of the ether. The ether was a fundamental physics problem that AlbertEistein and Hendrik Lorentz were unable to fully resolve throughout their lives.