Nothing is really known about the origin of the world-famous “pitch-drop experiment” at the School of Physics, Trinity College Dublin. Discovered in the 1980s during a clear-out of dusty cupboards, this curious glass funnel contains a dark, black substance. All we do know is that it was prepared in October 1944 (assuming you trust the writing on it). We don’t know who filled the funnel, with what exactly, or why.

Placed on a shelf at Trinity, the funnel was largely ignored by generations of students passing by. But anyone who looked closely would have seen a drop forming slowly at the bottom of the funnel, preparing to join older drops that had fallen roughly once a decade. Then, in 2013 this ultimate example of “slow science” went viral when a webcam recorded a video of a tear-drop blob of pitch falling into the beaker below.

The video attracted more than two million hits on YouTube (a huge figure back then) and the story was covered on the main Irish evening TV news. We also had a visit from German news magazine Der Spiegel, while Discover named it as one of the top 100 science stories of 2013. As one of us (SH) described in a 2014 Physics World feature, the iconic experiment became “the drop heard round the world”.

Pitching the idea

Inspired by that interest, we decided to create custom-made replicas of the experiment to send to secondary schools across Ireland as an outreach initiative. It formed part of our celebrations of 300 years of physics at Trinity, which dates back to 1724 when the college established the Erasmus Smith’s Professorship in Natural and Experimental Philosophy.

An outreach activity that takes 10 years for anything to happen is obviously never going to work. Technical staff at Trinity’s School of Physics, who initiated the project, therefore experimented for months with different tar samples. Their goal was a material that appears solid but will lead to a falling drop every few months – not every decade.

After hitting upon a special mix of two types of bitumen in just the right proportion, the staff also built a robust experimental set-up consisting of a stand, a funnel and flask to hold any fallen drops. Each was placed on a wooden base and contained inside a glass bell jar. There were also a thermometer and a ruler for data-taking along with a set of instructions.

On 27 November 2024 we held a Zoom call with all participating schools, culminating in the official call to remove the funnel stopper

Over 100 schools – scattered all over Ireland – applied for one of the set-ups, with a total of 37 selected to take part. Most kits were personally hand-delivered to schools, which were also given a video explaining how to unpack and assemble the set-ups. On 27 November 2024 we held a Zoom call with all participating schools, culminating in the official call to remove the funnel stopper. The race was on.

Joining the race

Each school was asked to record the temperature and length of the thread of pitch slowly emerging from the funnel. They were also given a guide to making a time-lapse video of the drop and provided with information about additional experiments to explore the viscosity of other materials.

To process incoming data, we set up a website, maintained by yet another one of our technical staff. It contained interactive graphs showing the increased in drop length for every school, together with the temperature when the measurement was taken. All data were shared between schools.

After about four months, four schools had recorded a pitch drop and we decided to take stock at a half-day event at Trinity in March 2025. Attended by more than 80 pupils aged 12–18 and teachers from 17 schools, we were amazed by how much excitement our initiative had created. It spawned huge levels of engagement, with lots of colourful posters.

By the end of the school year, most had recorded a drop, showing our tar mix had worked well. Some schools had also done experiments testing other viscous materials, such as syrup, honey, ketchup and oil, examining the effect of temperature on flow rate. Others had studied the flow of granular materials, such as salt and seeds. One school had even captured on video the moment their drop fell, although sadly nobody was around to see it in person.

Some schools displayed the kits in their school entrance, others in their trophy cabinet. One group of students appeared on their local radio station; another streamed the set-up live on YouTube. The pitch-drop experiment has been a great way for students to learn basic scientific skills, such as observation, data-taking, data analysis and communication.

As for teachers, the experiment is an innovative way for them to introduce concepts such as viscosity and surface tension. It lets them explore the notion of multiple variables, measurement uncertainty and long-time-scale experiments. Some are now planning future projects on statistical analysis using the publicly available dataset or by observing the pitch drop in a more controlled environment.

Wouldn’t it be great if other physics departments followed our lead?

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More than a quarter of UK university physics departments could be shut down within the next couple of years, according to a survey carried out by the Institute of Physics (IOP). It also reveals that almost 60% of departmental heads expect physics degree courses to close within that time, while more than 80% of those questioned say they expect to see job losses.

The survey findings are published in a new report – Physics Matters: Funding the Foundations of Growth– that says UK university physics is a “major strength” of the UK university system and vital to “national security and technological sovereignty”. The UK currently has about 17,000 physics undergraduates and more than 6000 physics department staff, with about 1 in 20 jobs in the UK using physics-related knowledge and skills.

However, the report adds that this strength cannot be taken for granted and points to “worrying signs” that university physics has started to “punch below its weight”. This is compounded, the IOP says, by a drop in the number of students studying physics at UK universities and flat grant funding for UK physics departments over the past decade.

In addition, UK universities are being hit by financial challenges and funding shortfalls caused by inflationary pressure and a drop in international student numbers. Given that physics comes with high teaching costs, the report states this threatens a “perfect storm” for university physics departments.

Close to breaking point

The survey of 31 departmental heads, which was carried out in August, found that three unnamed departments face imminent closure, with a further 11 anticipating shutting courses. When asked to look ahead over the next two years, eight say they expect to face closure, with 18 anticipating course closures.

One head of physics at a UK university told the IOP, which publishes Physics World, that they are concerned they are “close to breaking point”. “Our university has a £30m deficit,” the anonymous head said. “Staff recruitment is frozen, morale is low. Yet colleagues in our school continue to deliver with less and less and under increasing pressure.”

Jonte Hance, a quantum physicist at Newcastle University, told Physics World that the threat of closures is “horrifying”. In 2004, Newcastle closed its physics department before reopening it over a decade later. “Worryingly, this approach – ignoring, or even cutting, any departments that don’t make a massive short-term profit – doesn’t just seem to be a panicked knee-jerk response on the part of vice-chancellors, but part of a concerted and planned strategy, aiming to turn universities into business incubators,” adds Hance.

Towards a cliff edge

The IOP is now calling on the UK government to commit additional funding for science and engineering departments to help with the operation, maintenance, refurbishment and building of labs and technical facilities. It also wants an “early-warning system” created for departments at risk as well as changes to visa policy to remove international students from net migration figures, retain the graduate visa in its current form, and make “global talent and skilled worker” visas more affordable.

While we understand the pressures on public finances, it would be negligent not to sound the alarm

Keith Burnett

In addition, the IOP wants the UK government to develop a decade-long plan that includes reform of higher-education funding so universities can fund the cost of teaching “important subjects such as physics”. Keith Burnett, the outgoing IOP president, warns that without such action, the UK is “walking towards a cliff edge”, although he believes there is still time to “avert a crisis”.

“While we understand the pressures on public finances, it would be negligent not to sound the alarm for a national capability fundamental to our wellbeing, competitiveness and the defence of the realm,” says Burnett, who is former vice-chancellor at the University of Sheffield and former chair of physics at the University of Oxford. “Physics researchers and talented physics students are our future, but if action isn’t taken now to stabilise, strengthen and sustain one of our greatest national assets, we risk leaving them high and dry.”

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Errors in some of this year’s A-level physics exam papers could leave students without good enough grades to study physics at university. The mistakes have forced Tom Grinyer, chief executive of the Institute of Physics (IOP), to write to all heads of physics at UK universities, calling on them to “take these exceptional circumstances into account during the final admissions process”. The IOP is particularly concerned about students whose grades are lower than expected or are “a significant outlier” compared to other subjects.

The mistakes in question appeared in the physics (A) exam papers 1 and 2 set by the OCR exam board. Erratum notices had been issued to students at the start of the exam in June, but a further error in paper 2 was only spotted after the exam had taken place, causing some students to get stuck. Physics paper 2 from the rival AQA exam board was also seen to contain complex phrasing that hindered students’ ability to answer the question and led to time pressures.

A small survey of physics teachers carried out after the exam by the IOP, which publishes Physics World, reveals that 41% were dissatisfied with the OCR physics exam papers and more than half (58%) felt that students had a negative experience. Two-thirds of teachers, meanwhile, reported that students had a negative experience during the AQA exam. A-levels are mostly taken by 18 year olds in England, Wales and Northern Ireland, with the grades being used by universities to decide admission.

Grinyer says that the IOP is engaging in “regular, open dialogue with exam boards” to ensure that the assessment process supports and encourages students, while maintaining the rigour and integrity of the qualification. “Our immediate concern,” Grinyer warns, “is that the usual standardization processes and adjustments to grade boundaries – particularly for the OCR paper with errors – may fail to compensate fully for the negative effect on exam performance for some individuals.”

An OCR spokesperson told Physics World that the exam board is “sorry to the physics students and teachers affected by errors in A-level physics this year”. The board says that it “evaluated student performance across all physics papers, and took all necessary steps to mitigate the impact of these errors”. The OCR claims that the 13,000 students who sat OCR A-level physics A this year “can be confident” in their A-level physics results.

“We have taken immediate steps to review and strengthen our quality assurance processes to prevent such issues from occurring in the future,” the OCR adds. “We appreciated the opportunity to meet with the Institute of Physics to discuss these issues, and also to discuss our shared interest in encouraging the growth of this vital subject.”

Almost 23,500 students sat AQA A-level physics this year and an AQA spokesperson told Physics World that the exam board “listened to feedback and took steps to make A-level physics more accessible” to students and that there “is no need for universities to make an exception for AQA physics outcomes when it comes to admissions criteria”.

“These exam papers were error-free, as teachers and students would expect, and we know that students found the papers this year to be more accessible than last year,” they say. “We’ll continue to engage with any feedback that we receive, including feedback from the Institute of Physics, to explore how we can enhance our A-level physics assessments and give students the best possible experience when they sit exams.”

Students ‘in tears’

The IOP now wants A-level physics students to be given a “fair opportunity” when it comes to university admissions. “These issues are particularly concerning for students on widening participation pathways, many of whom already face structural barriers to high-stakes assessment,” the IOP letter states. “The added challenge of inaccessible or error-prone exam papers risks compounding disadvantage and may not reflect the true potential of these students.”

The IOP also contacted AQA last year over inaccessible contexts and language used in previous physics exams. But despite AQA’s assurances that the problems would be addressed, some of the same issues have now recurred. Helen Sinclair, head of physics at the all-girls Wimbledon High School, believes that the “variable quality” of recent A-level papers have had “far-reaching consequences” on young people thinking of going into physics at university.

“Our students have exceptionally high standards for themselves and the opaque nature of many questions affects them deeply, no matter what grades they ultimately achieve. This has even led some to choose to apply for other subjects at university,” she told Physics World. “This is not to say that papers should not be challenging; however, better scaffolding within some questions would help students anchor themselves in what is an already stressful environment, and would ultimately enable them to better demonstrate their full potential within an exam.”

Students come out of the exams feeling disheartened, and those students share their perceptions with younger students

Abbie Hope, Stokesley School

Those concerns are echoed by Abbie Hope, head of physics at Stokesley School near Middlesbrough. She says the errors in this year’s exam papers are “not acceptable” and believes that OCR has “failed their students”. Hope says that AQA physics papers in recent years have been “very challenging” and have resulted in students feeling like they cannot do physics. She also says some have emerged from exam halls in tears.

“Students come out of the exams feeling disheartened and share their perceptions with younger students,” she says. “I would rather students sat a more accessible paper, with higher grade boundaries so they feel more successful when leaving the exam hall, rather than convinced they have underachieved and then getting a surprise on results day.” Hope fears the mistakes will undermine efforts to encourage uptake and participation in physics and that exam boards need to serve students and teachers better.

A ‘growing unease’

Rachael Houchin, head of physics at Royal Grammar School Newcastle, says this year’s errors have added to her “growing unease” about the state of physics education in the UK. “Such incidents – particularly when they are public and recurring – do little to improve the perception of the subject or encourage its uptake,” she says. “Everyone involved in physics education – at any level – has a duty to get it right. If we fail, we risk physics drifting into the category of subjects taught predominantly in selective or independent schools, and increasingly absent from the mainstream.”

Hari Rentala, associate director of education and workforce at the IOP, is concerned that the errors unfairly “perpetuate the myth” that physics is a difficult subject. “OCR appear to have managed the situation as best they can, but this is not much consolation for how students will have felt during the exam and over the ensuing weeks,” says Rentala. “Once again AQA set some questions that were overly challenging. We can only hope that the majority of students who had a negative experience as a result of these issues at least receive a fair grade – as grade boundaries have been adjusted down.”

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