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How did special relativity lead Einstein to recognize the need for a new theory of gravity?

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gravitational lens — gravity A galactic cluster, about five billion light-years away, produces a tremendous gravitational field that “bends” light around it. This lens produces multiple copies of a blue galaxy about twice as distant. Four images are visible in a circle surrounding the lens; a fifth is visible near the center of the picture, which was taken by the Hubble Space Telescope.

Albert Einstein recognized the need for a new theory of gravity because Isaac Newton’s law of gravitation was fundamentally incompatible with special relativity.1

Newton’s theory relied on the concept of "action at a distance," implying that gravitational interaction between two objects, such as the Sun and Earth, occurs instantaneously. However, special relativity establishes that no interaction or information can propagate faster than the speed of light, thereby precluding the possibility of instantaneous gravitational effects.1

To resolve this conflict, Einstein sought a new framework. He was guided by the principle of equivalence, which posits that it is impossible to distinguish between the effects of gravity and acceleration on a local scale. Through his thought experiments, he concluded that gravity must influence the path of light and should be treated as a geometric phenomenon, eventually leading to his general theory of relativity.234