Trinity College’s Pitch-Drop Experiment Sparks Student Engagement

The famous pitch-drop experiment at Trinity College Dublin has transformed from a long-standing scientific curiosity into an engaging educational outreach initiative. Originally discovered in the 1980s, the experiment features a glass funnel filled with pitch, a viscous substance that drips at a glacial pace. Though the funnel was prepared in October 1944, its origins remain a mystery, with only the date of preparation documented. Over the years, it was largely overlooked by students passing through the School of Physics.

In 2013, the experiment gained unexpected popularity when a webcam captured a pitch drop falling into a beaker, leading to over two million views on YouTube. This event drew significant media attention, including coverage from Der Spiegel and recognition from Discover as one of the top 100 science stories of that year. The attention inspired Stefan Hutzler and Louise Bradley to develop a replica of the experiment for schools across Ireland, aiming to celebrate 300 years of physics at Trinity.

Turning a Slow Experiment into an Engaging Initiative

Recognizing that an experiment requiring a decade for results would not be practical for outreach, Trinity’s technical staff worked to create a version of the pitch-drop experiment that would yield results more frequently. After extensive testing with various tar samples, they developed a mix of two types of bitumen that would produce drops every few months, rather than every decade. The experimental setup included a stand, funnel, flask, and additional equipment for measurement and data collection, all housed in a glass bell jar.

On November 27, 2024, a Zoom call connected over 100 participating schools for the official launch. A total of 37 schools were selected to receive the kits, which were delivered personally by the team. Each school was equipped with detailed instructions, a thermometer, and a ruler to record measurements of the pitch drop as it formed.

Students were encouraged to document the temperature and length of the pitch thread, and they received guidelines for creating time-lapse videos of the drops. To facilitate data sharing, a dedicated website was established, showcasing interactive graphs that displayed the progress of each school’s experiment. This collaborative approach allowed students to engage with the science behind viscosity and the properties of materials.

Results and Educational Impact

After approximately four months, several schools recorded their first pitch drops. A half-day event held at Trinity in March 2025 brought together more than 80 students and teachers from 17 schools to celebrate their achievements. The initiative fostered enthusiasm for scientific inquiry, with students producing colorful posters and sharing their findings. By the end of the school year, most participating schools had successfully recorded a drop, validating the effectiveness of the new tar mix.

Beyond the pitch-drop experiment, schools explored the viscosity of other materials, such as syrup and honey, and examined the impact of temperature on flow rates. Some students even ventured into experiments with granular materials like salt and seeds. One school captured their pitch drop on video, although no one was present to witness the moment live.

The pitch-drop experiment has proven to be a significant educational tool, allowing students to develop key scientific skills, including observation and data analysis. For teachers, it offers an innovative method to introduce concepts like viscosity, surface tension, and the complexities of long-term experiments. Moreover, some educators are now planning future projects that utilize the publicly available dataset for statistical analysis or more controlled observations of the pitch drop.

The success of this initiative highlights the potential for similar outreach programs across physics departments worldwide, inspiring a new generation of students to engage with science in meaningful ways.