As the second year of the massive Russo-Japanese War begins, more than 100,000 die in the largest world battles of that era, and the war chaos leads to the 1905 Russian Revolution against Nicholas II of Russia (Shostakovich's 11th Symphony is subtitled The Year 1905 to commemorate this) and the start of Revolution in the Kingdom of Poland. Canada and the U.S. expand west, with the Alberta and Saskatchewan provinces and the founding of Las Vegas. 1905 is also the year in which Albert Einstein, at this time resident in Bern, publishes his four Annus Mirabilis papers in Annalen der Physik (Leipzig) (March 18, May 11, June 30 and September 27), laying the foundations for more than a century's study of theoretical physics.
January 1905
January 1 – In a major defeat in the Russo-Japanese War, Russian General Anatoly Stessel surrenders Port Arthur, located on mainland China, to the Japanese. On January 3, Japan formally repossesses the port, and renames it Ryojun, holding it for the next 40 years. The area will revert in 1945 to China, and become the Lushunkou District.
January 4
Gheorghe Grigore Cantacuzino becomes Prime Minister of Romania for the second time, having previously served from 1899 to 1900, and remains in office for more than two years.
The city of Bend, Oregon, plotted out in 1900 by Alexander Drake, is incorporated as a town for local logging companies, and will have a population of 536 in 1910. By the year 2020, it will have almost 100,000 residents.
January 5 – Baroness Emma Orczy's play The Scarlet Pimpernel, the forerunner of her novel, opens at the New Theatre in London, beginning a run of 122 performances and numerous revivals.
January 6
The Lick Observatory announces the discovery of a sixth moon of Jupiter, made by their astronomer Charles D. Perrine. Unlike the first five Jovian satellites discovered, the sixth one will be referred to by number as "Jupiter VI" until 1975, when named Himalia.
The U.S. Senate confirms the nomination of William D.