From Einstein to the Event Horizon
Prof. Dunajski began his lecture with the basics of general relativity, introducing the characters of Bob and Alice – observers who help us understand the relativity of time and space. In an accessible and graphic way, he explained the concept of the event horizon – the boundary beyond which there is no return. This is precisely what defines a black hole: anything that crosses it is irrevocably sucked inside, even light.
Although the term "black hole" is common today, its origins are ambiguous. One metaphor refers to the colonial prison in Calcutta – a space with no exit – which perfectly captures the nature of this peculiar structure.
How to see the invisible?
Black holes cannot be observed directly, but we can detect their presence through the effects they have on their surroundings. Professor Dunajski described the methods used to detect them: from the deviation of the orbits of other stars, through X-rays to gravitational waves. The first image of a black hole's shadow obtained using the Event Horizon Telescope was a breakthrough.
A major highlight was the presentation of animations showing the sizes of various black holes – the scale comparisons of these phenomena were impressive and allowed for a better understanding of their power.
Physics and film
The lecture was enriched by pop culture references. "Interstellar" is an example of how cinema can collaborate with science – thanks to Kip Thorne's work, the film depicts a realistic model of a black hole. Meanwhile, "Back to the Future" was treated with a wink – time travel, while fascinating, is impossible given current knowledge.
Singularity and the limits of our knowledge
There is a singularity at the centre of a black hole – a point where the known laws of physics cease to apply. The cosmic censor hypothesis posits that these singularities are hidden within the event horizon, but their nature remains one of the greatest mysteries of modern science.
What’s next?
Prof. Dunajski concluded his lecture with a reflection on the future of black hole research – from the search for primordial black holes to the paradox of information loss.
While many questions remain open, one thing is certain: black hole research is leading us toward a deeper understanding of time, space and information – and the very nature of reality.
The event was possible thanks to funding obtained by the University of Lodz Foundation through the OPUS Centre competition. The public project "Academic Lodz – Scientific, Creative and Multicultural 2025" is financed from the City of Lodz budget.
Edit: Magdalena Paszko, Centre for External Relations and Social Responsibility of the University, University of Lodz
Graphics: Centre for Brand Communications, University of Lodz
