How does gravitational lensing provide evidence for general relativity?

Gravitational lensing provides critical evidence for general relativity by confirming that gravity is not merely a force, but a consequence of the curvature of space-time. According to Albert Einstein, massive objects deform space-time, forcing light to follow curved paths known as geodesics rather than traveling in straight lines.12

This phenomenon was first empirically supported during the 1919 solar eclipse, when astronomers observed that starlight passing near the Sun was deflected by the predicted amount. Later, the 1979 discovery of gravitational lenses provided further validation. In these instances, a massive object—such as a galaxy—acts like a lens, bending and focusing light from more distant objects. This can cause a single background source to appear distorted, magnified, or even as multiple images, directly demonstrating that gravity alters the trajectory of light as dictated by the geometric principles of general relativity.134