Proving Ground
Cabinet of curiosities
Twelve objects from his life to discover.
Finds appear by themselves while you explore the site: when you visit a chapter, try an experiment or finish a journey. Silhouettes show where to look.
0 of 12 discovered
No. 1 · c. 1884
The compass
When Albert was four or five and ill in bed, his father showed him a compass.
That the needle always pointed north without anyone touching it struck him as a miracle.
Looking back (Autobiographical Notes, 1949), he described it as a lasting impression: something deeply hidden must lie behind things.
No. 2
Still hidden
A sheet of paper that sets a rumour straight. Look at it very closely, with the detective’s lens.
No. 2 · 1896
The Aarau certificate
On 3 October 1896 the education council of the canton of Aargau issued the 17-year-old Albert Einstein his school-leaving certificate in Aarau.
The Swiss scale runs from 6 (best) to 1: he got a 6 in history, algebra, geometry, descriptive geometry and physics, and a 3 in French, his lowest mark.
Anyone who mistakes the Swiss scale for the German one reads those sixes as failures.
No. 3
Still hidden
A stamp that came down on hundreds of applications. Two ways lead to it.
No. 3 · 1902
The patent-office stamp
On 23 June 1902 Einstein started work as a technical expert, 3rd class, at the Swiss Patent Office in Bern.
Applications on his desk included a gravel sorter and an electric typewriter; in 1903 the office made his post permanent.
It is conceivable that thinking about signals and clock synchronisation in submitted inventions fed his ideas on simultaneity. That is an interpretation (for example by Peter Galison), not proof.
No. 4
Still hidden
Not a museum piece but a device for thinking. It ticks in an experiment.
No. 4 · thought device
The light clock
Two mirrors with a flash of light bouncing between them: every round trip is one tick.
If the clock flies past an observer, the light must take a longer, slanted path. Because the speed of light is the same for everyone, the moving clock ticks more slowly.
The light clock is a textbook picture for deriving time dilation, not a surviving object.
No. 5
Still hidden
A glass bulb with no air in it, and a light-quantum idea inside. It lights up in an experiment.
No. 5 · idea of 1905
The photocell
In 1905 Einstein explained the photoelectric effect with light quanta: light strikes a metal in portions and knocks out single electrons.
A photocell uses exactly this: light hits a metal surface in an evacuated glass bulb, and the freed electrons flow as a current to a second electrode.
In 1914 Robert Millikan showed that the energy of the electrons grows with the frequency of the light, as Einstein had predicted. The 1921 Nobel Prize in Physics (awarded in 1922) cited his “discovery of the law of the photoelectric effect”.
No. 6
Still hidden
Pages full of crossed-out attempts. A dent in a sheet leads to them.
No. 6 · 1912/13
The Zurich Notebook
In the Zurich Notebook Einstein recorded his calculations on gravitation in 1912/13, with the help of the mathematician Marcel Grossmann.
The pages hold much of the foundational work for general relativity: the search for equations that describe gravity as the curvature of spacetime.
In 1913 he and Grossmann published the “Entwurf”, a forerunner; the final field equations followed in November 1915.
No. 7
Still hidden
A sheet of glass with stars on it. An eclipse leads to it.
No. 7 · 1919
Eddington’s photographic plate
On 29 May 1919 two British expeditions, on the island of Príncipe and at Sobral in Brazil, photographed the stars around the eclipsed Sun.
The Sun stood in front of the Hyades, a bright group of stars. Compared with night-time plates of the same field, the stars should appear shifted if the Sun bends light.
The results were presented on 6 November 1919 at a joint meeting of the Royal Society and the Royal Astronomical Society and marked the beginning of Einstein’s international fame.
No. 8
Still hidden
An instrument he played when the equations stalled. It is found where his private life is told.
No. 8 · from childhood
The violin “Lina”
Einstein played the violin from childhood; at 13 he discovered Mozart’s violin sonatas.
He gave his violins the name “Lina”.
A violin from 1894, bought in Munich and inscribed “Lina”, was auctioned in October 2025 after the music researcher Paul Wingfield judged it very likely to be Einstein’s.
No. 9
Still hidden
A small boat on a Brandenburg lake. It belongs to the story of the house in the woods.
No. 9 · 1929
The sailboat “Tümmler”
For his 50th birthday in 1929 friends gave him the sailboat “Tümmler” (“porpoise”).
He sailed it from his summer house in Caputh near Potsdam until 1932, although he could not swim.
The Nazis confiscated the boat in 1933 and later sold it.
No. 10
Still hidden
A document he handed in. It belongs to the spring of 1933.
No. 10 · 1933
The German passport
On 28 March 1933, after landing in Antwerp on his return from the USA, Einstein surrendered his German passport, formally renouncing his German citizenship.
The renunciation was at first refused; the Nazi government revoked his citizenship on 24 March 1934.
Sources differ on the place: English Wikipedia names the consulate in Antwerp, German Wikipedia the embassy in Brussels.
No. 11
Still hidden
Two typed pages with one signature. The letter itself can be read in full.
No. 11 · 1939
The letter to Roosevelt
The letter is dated 2 August 1939. That day Szilárd and Teller visited Einstein on Long Island; the English text was typed in New York and sent to him to sign.
It warned that uranium might become a new source of energy and lead to bombs of a new type, and suggested that the government keep in contact with the physicists working on chain reactions.
It reached President Roosevelt only on 11 October 1939, delivered by Alexander Sachs.
No. 12
Still hidden
One of his last public signatures. It belongs to the last years of his life.
No. 12 · 1955
The Russell–Einstein Manifesto
The manifesto warned of the dangers of nuclear weapons and called on governments to find peaceful solutions to conflicts.
Einstein signed it shortly before his death on 18 April 1955; it was issued in London on 9 July 1955.
Eleven people signed, nine of them Nobel laureates at the time. From it grew the Pugwash Conferences, the first of which took place in 1957.
All drawings are by heimseiten.de and show the kind of object, not the original itself.