From tulip to quantum: Leiden discoveries revisited
To mark the university’s 450th anniversary, the Leiden Discoveries science route has been updated and was relaunched on the Night of Discoveries. New signs in town and a revamped website tell Leiden residents and visitors the stories of the city’s spectacular discoveries.
‘A light bulb symbolises the route. It’s a visual metaphor with light representing insight’, said Rector Magnificus Hester Bijl, as she presented Mayor Peter Heijkoop with a lit lamp. ‘We all know the image of a light bulb above someone’s head, that “aha” moment. Light banishes darkness, just like an idea or discovery can banish ignorance.’
From the tulip to the constitution
The tulip, superconductivity, the constitution, radio astronomy: these discoveries and inventions were made in Leiden. Where and by whom? Leiden Discoveries tells the stories.
Signs dotted throughout Leiden’s centre explain what was discovered in a particular spot and by whom. All these discoveries can also be found on a redesigned website with routes taking in all of them.
The list includes famous names such as Einstein, Clusius and Thorbecke and discoveries such as the coldest place on Earth. Others are less well-known, but no less important. George Uhlenbeck and Samuel Goudsmit, for example, who discovered in 1925 an unexpected property of electrons: that they could ‘spin’ in two directions. Scientists later termed this ‘electron spin’. The discovery laid the groundwork for the quantum computer.
Smartphone
The route features discoveries from both the distant and more recent past that had a huge impact in their time and continue to do so today.
The most famous discovery made by Van Musschenbroeck, the Leyden Jar – a capacitor from 1746 – still lives on: the smartphone you can Leiden Discoveries on, contains at least 500 (!) smaller, modern versions of this Leiden discovery.
‘Leiden is proud to show its scientific history’, said Bijl. ‘And it’s not just history because all these discoveries had and continue to have an enormous impact on everyday life for you and me.’
Routes on the website
The bilingual website has walking tours of the discoveries and features portraits of the researchers. You can also view these portraits in colour – the old pictures and photos have been colourised with AI.
Ahead of their time
Leiden Discoveries is not new, but has been updated. The initiative of Professor Ton van Raan, it was realised in 2015 with the support of partners including the Municipality of Leiden as a gift to and from the city to mark our 440th anniversary. In 2025, the university is celebrating its 450th anniversary, and the theme is Ahead of the Times. The updated Leiden Discoveries show once again that with their groundbreaking discoveries, Leiden’s researchers were often ahead of their time.