The 1905 Paper, in the Annus Mirabilis
Most readers will instinctively pair Einstein's name with relativity. Yet the 1921 Nobel Prize in Physics that bears his name was awarded not for relativity but for his work on the photoelectric effect. The relevant paper appeared in Annalen der Physik in 1905, alongside special relativity and the paper on Brownian motion, as one of four famous contributions in his "miracle year."
The effect itself had been experimentally characterized by Philipp Lenard in 1902: when light hits a metal surface, electrons come out. What classical wave theory could not explain is that the energy of each emitted electron depends on the frequency of the light, not on its intensity. Einstein's response was bold. He suggested that light travels in discrete packets, each carrying energy hν proportional to its frequency. It was a proposal to reintroduce a particle aspect into an optics that had been almost exclusively wavelike for a century.
Resistance in the Committee
Through the 1910s, Einstein was nominated repeatedly for the Physics Prize, and each year the prize went elsewhere. Inside the Royal Swedish Academy of Sciences' selection committee, there were members who regarded relativity as too speculative, too detached from laboratory evidence, to honor outright.
The most visible opponent was Allvar Gullstrand, an ophthalmologist who had himself won the 1911 Prize in Physiology or Medicine. He attacked general relativity on both mathematical and philosophical grounds. The chemist Svante Arrhenius (the 1903 Chemistry laureate) was also cautious about the experimental status of the theory. Philipp Lenard — ironically the experimentalist whose 1902 data Einstein's photoelectric paper had explained — moved through the 1920s from scientific opposition into an increasingly anti-Semitic campaign against Einstein's work.
The 1921 Prize, Reserved
In 1921, the committee decided that none of the year's nominees met the criteria laid out in Nobel's will, and that the prize money should be reserved. The Nobel Foundation's statutes allow this. When the decision was revisited the following year, the committee retroactively awarded the 1921 Physics Prize to Einstein, in November 1922. The 1922 prize itself went to Niels Bohr.
The citation was carefully phrased:
"for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect"
Relativity appears nowhere in the sentence. Neither does the particle nature of light, strictly speaking; the word "law" is chosen as a neutral hedge. Every clause reads as a compromise, and the committee's hesitation is visible in the very wording they approved.
Absent from the Ceremony, Aboard the Kitano Maru
When the decision was finalized in the autumn of 1922, Einstein was not in Sweden. He had accepted an invitation from the publisher Sanehiko Yamamoto, founder of the Japanese magazine Kaizō, to tour East Asia as a lecturer. With his wife Elsa, he had sailed from Marseille on 8 October aboard the Japanese ocean liner Kitano Maru.
He learned of the award through a telegram handed to him by the ship's captain while at sea, in the stretch of his voyage between Hong Kong and Shanghai. The exact date and location vary slightly between sources, so the safer phrasing is simply that the news reached him mid-voyage. He missed the December ceremony in Stockholm; the German ambassador accepted the prize on his behalf. In Japan, Einstein lectured across Kobe, Kyoto, Tokyo, Sendai, Nagoya and Fukuoka, under an arrangement in which Kaizōsha paid him roughly £2,000 for the series.
The Prize Money and Mileva
The prize itself was worth about 121,572 Swedish kronor at the time, and it had its own quiet second life. Einstein and his first wife, Mileva Marić, had divorced in 1919. The divorce agreement reportedly included a clause directing any future Nobel Prize money to Mileva and their two sons, to be held in trust at a Swiss bank — this two years before the prize was awarded.
When the 1921 Physics Prize finally materialized, Einstein is said to have honored the arrangement. Mileva used part of the funds to buy a house at Huttenstrasse in Zurich, where she lived with their sons. The exact wording of the clause, and the later disposition of the money, remain matters of historical debate. What is not in dispute is that a prize given to honor an individual scientist flowed, quietly, to a first wife who had herself been part of his student-era intellectual life, and to the children they raised together.
Quantum Theory's Delayed Vindication
It is often written that the committee chose the photoelectric effect as the "safe" alternative to relativity. That description is largely fair. Relativity would go on to accumulate experimental confirmation — Mercury's perihelion, the bending of starlight, the 2015 detection of gravitational waves — far beyond what the committee had in hand in 1921.
The irony, though, is that the "safer" choice turned out to be the more radical paper in disguise. The light-quantum hypothesis fed directly into Bohr's atomic model, into Compton scattering, and into the matrix and wave mechanics of the late 1920s. The 1921 Physics Prize thus managed, while ostensibly avoiding Einstein's biggest theoretical move, to bless the very paper that seeded the quantum revolution. As Nobel citations go, it is one of the most oblique.