singularity

History

The first mathematical description of a singularity appeared in Karl Schwarzschild's solution in 1916. Later, Roger Penrose and Stephen Hawking proved that singularities inevitably arise during the collapse of massive stars.

How it works

A rubber sheet bends under the weight of a ball—this is how gravity works; if the ball is compressed into a point, the sheet ruptures, forming an infinitely sharp funnel. Similarly, spacetime 'tears' at a singularity, creating infinite curvature.

History

The first mathematical description of a singularity appeared in Karl Schwarzschild's solution in 1916. Later, Roger Penrose and Stephen Hawking proved that singularities inevitably arise during the collapse of massive stars.

How it works

A rubber sheet bends under the weight of a ball—this is how gravity works; if the ball is compressed into a point, the sheet ruptures, forming an infinitely sharp funnel. Similarly, spacetime 'tears' at a singularity, creating infinite curvature.

History

In 1916, Karl Schwarzschild found the first exact solution to Einstein's equations for a spherically symmetric body, containing a singularity at the center. For a long time, the singularity was considered a mathematical artifact. In the 1960s, Roger Penrose and Stephen Hawking proved singularity theorems, showing the inevitability of singularities in gravitational collapse and cosmology within classical GR. John Archibald Wheeler popularized the term 'black hole' and, together with his students, developed approaches to quantizing gravity to eliminate singularities; this problem remains unsolved.

How it works

A singularity occurs when the spacetime curvature and the stress-energy tensor in Einstein's equations tend to infinity. In the case of the collapse of a star with a mass exceeding the Oppenheimer-Volkoff limit, gravity overcomes the pressure of degenerate gas, and matter is compressed without limit down to the Planck scale (10^-35 m), where quantum corrections must come into play. In quantum cosmology, the Big Bang singularity may be replaced by quantum tunneling from 'nothing' or a cyclic bounce. Modern theories such as loop quantum gravity and string theory propose mechanisms for resolving singularities through discretization of spacetime.

Open problems & fun facts

Does a physical singularity exist, or is it smoothed out by quantum gravity?; How to resolve the problem of cosmic censorship: are singularities always hidden by event horizons?; Was the Big Bang a singularity, and what was 'before'?

💡 In Kerr's solution for a rotating black hole, the singularity has the shape of a ring, which theoretically allows for the possibility of passing through it into other universes, although any attempt would lead to destruction.