What was Karl Swartzchild the first to do?

• A. Make a connection between gravity and black holes
• B. Prove black holes don't exist
• C. Publish a theory of quantum gravity
• D. Propose the heliocentric model

Answer: (A)

Gravity under general relativity can create regions from which light cannot escape. Karl Schwarzschild was the first to derive an exact solution to Einstein’s field equations for a spherical, non-rotating mass, showing that a sufficiently compact mass produces a boundary—the Schwarzschild radius—where escape is impossible. This was the first clear link between gravity and the possibility of a black hole within the theory, paving the way for the concept that gravity alone can form such ultra-compact objects. The other statements don’t fit this historical achievement: he didn’t argue that black holes don’t exist, didn’t publish a theory of quantum gravity, and didn’t propose the heliocentric model.