Although he eventually became the most famous scientist in the world, Albert Einstein took a somewhat unconventional path to achieve that status...
At an early age, Einstein showed great intellectual ability, but his potential was stifled by the rigid and authoritarian teaching methods used in the German schools he attended. At age 16, although he scored well on the mathematics and science sections of the exit examination at the Luitpold Gymnasium preparatory school in Munich, he did not meet the overall requirements. Consequently, he did not receive a diploma and he was asked to leave. He later graduated from the Swiss Polytechnic School in Aarau, Switzerland at age 21.
Upon graduation, he was unable to find an academic job and settled for a position as a technical assistant examiner at the Swiss Patent Office in 1902, a job he worked until 1909. This allowed him to pursue physics in his spare time.
In 1905, at age 26 and still a patent clerk, Einstein published four groundbreaking papers in the journal Annalen der Physik (Annals of Physics), including the paper introducing his special theory of relativity (subsequently referred to as Einstein's "Annus Mirabilis" or miracle year papers). The paper was largely ignored by the physics community. Its concepts were considered too radical in challenging long-held classical notions of absolute space and time stemming from Sir Issac Newton's physics.
Undeterred by the lack of recognition,Einstein continued to build and expand on his special relativity theory. After giving a series of lectures in Berlin presenting his complete general theory of relativity to the Prussian Academy of Sciences, on November 25, 1915, Einstein submitted to the academy his first paper on general relativity, titled "The Field Equations of Gravitation." He followed that up with a series of papers expanding on and clarifying general relativity. In 1916 the papers were published together as a book titled "The Foundation of the General Theory of Relativity.”
As happened with special relativity, owing to the complicated mathematics and the challenge it presented to Newton's theory of gravity, his general relativity theory wasn’t broadly accepted by the scientific community . What was needed to convince the skeptics was a way to test the theory. That was where the total solar eclipse of 1919 came into the picture.
I won’t get into the nitty gritty details here (because I can’t) but Einstein's key insights in general relativity were that gravity arises from the curvature of spacetime, and that this curvature is caused by the presence of mass and energy. His field equations described how matter and energy determine the geometry of spacetime.
One of the key predictions of the relativity theory was that curvature of spacetime caused by the presence of massive objects, like stars or galaxies, would also affect the paths of light rays passing near to those objects. British astrophysicist Sir Arthur Eddington recognized that if there was a way to observe and measure that phenomenon, it would serve as a test of the theory.
In 1919, a remarkable astronomical event provided an opportunity for such a test. A total solar eclipse was predicted to occur on May 29th of that year. The eclipse would be visible from the island of Principe off the west coast of Africa and in parts of Brazil and the Pacific Ocean. Eddington realized that during the eclipse, the Moon's blocking of the bright light from the Sun's surface would enable the light from stars near the Sun's perimeter to become visible and their position could be observed and measured.
The idea was to measure the apparent positions of the nearby stars during the eclipse and compare them to their known positions when the Sun's gravity was not bending their light paths. To perform the measurement, Eddington led an expedition to Principe Island to observe and photograph stars near the Sun during the eclipse.
After analyzing the resulting photographic plates, Eddington and his team found that the positions of the stars near the Sun were slightly shifted from their expected positions, precisely as predicted by Einstein's theory of general relativity. The curvature of spacetime associated with the massive Sun was indeed causing the light from those stars to bend slightly as it passed close to the Sun.
This observation of the bending of starlight by the Sun's gravitational field was a remarkable confirmation of one of the most fundamental predictions of general relativity. It provided strong evidence that Einstein's revolutionary theory, which described gravity not as a force but as a consequence of the curvature of spacetime, was correct.
The 1919 solar eclipse observations are considered a pivotal moment in the history of science, as they helped establish general relativity as the new paradigm for understanding gravity and the nature of the universe on a cosmological scale. It also elevated Albert Einstein to celebrity status as he became the prototypical representative of a scientist for the rest of his life and beyond.