During the 1919 solar eclipse, starlight passing near the Sun was seen shifted by about 1.75 arcseconds from its true position. Why did this confirm Einstein's theory over Newton's? Step 1: Newton also predicted light bending (treating light as particles), but only half the observed amount — about 0.87 arcseconds. Step 2: Einstein's general relativity predicted double that: 1.75 arcseconds, because spacetime curvature affects light fully. Step 3: Eddington's eclipse measurements matched ~1.75 arcseconds, agreeing with Einstein and ruling out the Newtonian value. Answer: The measured deflection matched Einstein's prediction (1.75″) and not Newton's (0.87″), confirming that gravity curves spacetime itself.