Einstein sent in special relativity on 30 June 1905

Albert Einstein’s paper introducing special relativity, “Zur Elektrodynamik bewegter Körper” (“On the Electrodynamics of Moving Bodies”), reached the journal Annalen der Physik on 30 June 1905. It was printed about three months later, in September, so sites that say Einstein “published” relativity on 30 June are giving the date it arrived, not the date it appeared.

The paper reconciled two ideas that seemed to clash: the principle that physics works the same for anyone moving at a steady speed, and Maxwell’s theory of electromagnetism. The fix, as Einstein later put it, required “only” a new and more careful consideration of the concept of time.

Where it came from is something of a puzzle. Its author was a 26-year-old examiner at the Swiss patent office in Bern, a “patent expert (third class)” in the words of the historian John Stachel of the Einstein Papers project, largely self-taught and, by his own account, never having seen a theoretical physicist. Almost no paper trail survives: apart from the polished paper itself, the earlier documentary evidence is a couple of sentences in early letters, and Einstein’s later recollections are not always consistent.

Those recollections describe a breakthrough after a day spent wrestling with the problem alongside his friend and patent-office colleague Michele Besso, the only person the paper thanks. Within about six weeks of that step, Einstein said, he had worked out the consequences and sent the paper off.

He soon drew out a startling corollary: a body that gives off energy must lose mass, the relation now written E = mc². He was not yet sure of it, telling a friend:

“This thought is amusing and infectious, but I cannot possibly know whether the good Lord does not laugh at it and has led me up the garden path.”

Einstein stayed at the patent office until 1909, producing much of his celebrated work in his spare time.