Black Holes: From the Horizon to the Singularity

Black holes are among the most mysterious objects in the Universe, where gravity reaches its limit and familiar laws of physics stop working. Understanding them matters not only for astrophysicists: black holes serve as a natural laboratory for testing general relativity, help explain the evolution of galaxies, and raise questions about the fundamental structure of spacetime. This course will give you a systematic understanding of how black holes form, what happens at their boundary and inside them, and why they remain at the center of modern scientific discussions. The course program covers the key stages of a star’s life cycle: from a protostellar cloud to core collapse and the formation of a stellar-mass black hole. You will examine the concept of the event horizon — the boundary beyond which nothing, even light, can return — and learn how this surface relates to the singularity, a point of infinite density. Special attention is given to the first direct observations of black holes using the Event Horizon Telescope (EHT): how the image of the shadow of the supermassive black hole M87* was constructed and what it reveals about the object’s parameters. The course also covers theoretical aspects, including Hawking radiation, quantum effects near the horizon, and the information loss paradox. The course introduces the necessary physical models step by step, explaining how general relativity predicts the existence of black holes and how these predictions are supported by observations. The course methodology is built around conceptual explanations: you will not encounter cumbersome formulas, but you will master key ideas and logical connections. Common misconceptions are addressed, such as the idea that a black hole “sucks in” everything around it or that time stops inside it. You will learn to distinguish observable effects (gravitational lensing, accretion disks) from theoretical constructions and understand which aspects remain disputed. The course relies on modern data and includes analysis of real scientific publications adapted for a broad audience. The course is intended for students in natural science and engineering fields who are interested in astrophysics; physics and astronomy teachers who want to update their knowledge; participants in science popularization lectures and clubs who want a deeper understanding of the topic; and anyone who already knows the basics of physics and wants to understand current views on black holes without excessive mathematical load. By the end of the course, you will confidently use the concepts of event horizon, singularity, and photon sphere; be able to explain how gravitational collapse leads to the formation of a black hole and why it does not emit light; gain insight into black hole observation methods and the limitations of those methods; and be able to critically evaluate science popular articles and news on the topic. You will acquire the vocabulary and conceptual foundation needed for further independent study of more advanced courses in general relativity and astrophysics.