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The mystery of Einstein's sink

According to some stories, Einstein washed his hands there only once. According to others, students moved it as a joke. Whatever the case may be, Einstein's sink has enjoyed mythical status among students and employees of the Faculty of Science for decades. But what is the real story? Alumnus Alex Pietrow decided to find out.

The sink in De Sitterzaal

A grubby sink

Hidden away in a dark corner of De Sitterzaal – on the ground floor of the Oort Building – is a grubby sink. The sink. It looks ordinary, as is often the case with mythical objects. ‘I find objects such as Einstein’s sink interesting because their value lies in the fact that someone once touched or used them,’ says Pietrow, who previously visited and described Leiden’s science treasures for AtlasObscura. ‘The sink is special because it’s surrounded by so many legends. Nobody knew what was really true. That made it interesting for me to investigate.’ Pietrow published his findings in Studium.

The legend

Legend has it that Einstein washed his hands in the sink after a colloquium in the old physics laboratory in the centre of Leiden – renamed the Kamerlingh Onnes Laboratory (KOL) in 1932. ‘Another element that was always present in the stories was that the sink was moved to the Huygens Building because of its link with Einstein,’ says Pietrow. The sink in De Sitterzaal would be almost 100 years old, much older than the other sinks in the faculty therefore. To determine the age of the sink, Pietrow proceeded as a true detective.

The numbers under the sink

Mysterious numbers

After conducting a thorough search of the Faculty, Pietrow concluded that no other sink was like the one in De Sitterzaal. He also discovered mysterious numbers on the bottom of the sink, which might be a date: 24 January 1923. To verify whether the sink did come from the same period as Einstein, Pietrow decided to check with several antique dealers. Finally, the owner of LEEN – a shop specialising in historical building materials – identified the pattern of the drain as early twentieth century.

Did Einstein use the sink?

So the sink is old enough to have been used by Einstein, but was it ever in the KOL? Here, too, Pietrow did some excellent research: on several old photographs he spotted a white sink in the main lecture hall of the KOL, including a photo taken just after the KOL’s construction in 1922. He also thinks it's very likely that Einstein did use the sink.

‘It’s almost inevitable that Einstein washed his hands in the sink.’

‘Einstein was made professor by special appointment in Leiden in 1920. Until 1930, he regularly came to Leiden to teach and speak to his colleagues, all of whom worked in the KOL. And anyone who has ever worked with chalk knows that your hands get incredibly dirty. So it’s almost inevitable that Einstein washed his hands in the sink.’

The sink in the KOL (1944)

Financial problems

And then there are the stories about the relocation of the sink, which have contributed to its mythical status. When the physics institute moved to the new Huygens Building in 1998, the sink came along. ‘It was always assumed that this was due to the link with Einstein, but I discovered something else.’ According to staff members that Pietrow spoke to, the Faculty was facing financial problems at the time of the move. ‘And that’s why as much old furniture and instruments as possible were moved to the new building.’ Pietrow suspects that someone used the link with Einstein as an excuse for moving it. ‘But who spread that story is unclear.’


That the sink is popular, can’t be denied. It has its own Wikipedia page, is ranked 43rd on the list of attractions in Leiden on Tripadvisor and even features on t-shirts and mugs. But why is a simple sink so popular? ‘I think it’s the ordinary that makes the sink so interesting,’ says Pietrow. ‘Even heroes such as Einstein are not above everyday things like having dirty hands. It is also a tangible reminder of the bond between Einstein and Leiden.’

Keep the sink!

In 2015, the Faculty announced the construction of the second phase of a new building, to which the physics department will move. Pietrow discovered that Einstein’s sink was not on the moving list. ‘So, through the historical committee of F.Kaiser, the association for astronomy students, I started a petition to ensure the sink would be moved as well!’ Fans of Einstein’s sink can rest assured: the Faculty Board recently decided to move the historic sink to the large lecture hall in the new building, which according to plan will be finished in 2023. Until that time, you can still wash your hands in Einstein’s sink in De Sitterzaal!

Text: Bryce Benda

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