Why did it take so long for Einstein to get a Nobel Prize?
Initially his 1905 papers were considered baffling and unproven. He was first nominated for the prize in 1910 by the chemistry laureate Wilhelm Ostwald, who had rejected Einstein�s pleas for a job nine years earlier. Ostwald cited special relativity, but the Swedish committee was mindful of the charge in Alfred Nobel's will that the prize should go to "the most important discovery or invention," and it felt that relativity theory was not exactly either of those.
The dramatic announcement in November 1919 that the eclipse observations had confirmed parts of Einstein's theory should have made 1920 his year. But politics intervened. Up until then, the primary justifications for denying Einstein a Nobel had been scientific: his work was purely theoretical, and it putatively did not involve the "discovery" of any new laws. After the eclipse observations, the arguments against Einstein were tinged with more cultural and personal bias, including anti-Semitism. To his critics, the fact that he had suddenly achieved superstar status was evidence of his self-promotion rather than his worthiness of a Nobel. So the 1920 prize instead went to a scientist who was Einstein's scientific opposite: Charles-Edouard Guillaume, who had made his modest mark on science by assuring that standard measures were more precise and discovering metal alloys that had practical uses, including making good measuring rods.
By 1921, the public's Einstein mania was in full force, and there was a groundswell of support for him to win the Nobel — indeed, an expressed sense that it would be inexplicable if he didn't. But the committee was still not ready. The great impasse threatened to become embarrassing. To the rescue rode a theoretical physicist from the University of Uppsala, Carl Wilhelm Oseen, who joined the committee in 1922. He realized that the whole issue of relativity theory was so encrusted with controversy that it would be better to try a different tack. So Oseen pushed hard to give the prize to Einstein for "the discovery of the law of the photoelectric effect." Each part of that phrase was carefully calculated. It was not a nomination for relativity, of course. In fact, despite the way it has been phrased by some historians, it was not for Einstein's theory of light quanta, even though that was the primary focus of the relevant 1905 paper. Nor was it for any theory at all. Instead, it was for the discovery of a law.
Thus it was that Einstein became the recipient of the 1921 Nobel Prize, in the words of the official citation, "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect." Einstein would not, as it turned out, ever win a Nobel for his work on relativity and gravitation, nor for anything other than the photoelectric effect.