- What is the Schwarzschild radius and why do the equations become singular there?
- Why did it take another half century for the term 'black hole' to be attached to Schwarzschild's singularity?
Black Holes
Regions of spacetime with gravity so strong nothing escapes.
- Why does the exclusion principle explain why solid matter resists being compressed?
- Why would matter lose its rigidity and become compressible without the exclusion principle?
- Why did the Schwarzschild metric fail to describe most real astrophysical objects?
- What is the ergosphere, and what does the Kerr metric say can be extracted from it?
- What physical properties of black holes did the Van Impes cite as matching theological descriptions of Hell?
- What actually happens to matter that crosses a black hole's event horizon?
- How long did Stephen Hawking live after his motor neurone disease diagnosis, compared to the original prognosis?
- What major theoretical physics questions did Hawking's work address, such as Hawking radiation and the information paradox?
- What coincidence connects the date of Hawking's death to Pi Day and Einstein's birthday?
- What does the orange ring in the black hole image actually show, and what does the dark centre represent?
- How long after Einstein's general relativity predicted black holes did it take to produce an actual image of one?
- What did Roger Penrose prove in 1965 about black holes that even Einstein had doubted?
- Why did it take decades to move from Penrose's theoretical proof to observational confirmation of black holes?