Explore galaxies.im
black-holes.galaxies.im
History

From dark stars to a photograph

An idea in a letter in 1783 took more than two centuries to become a picture.

How this site works. Every fact is in our own words and linked to its source, beside it. Where good sources disagree, we show each version in a “Sources differ” box.

From an idea in a letter to a picture: black holes, 1783 to 2024.Drawing: our own, simplified and not to scale

John Michell’s dark stars

In 1783 the clergyman and astronomer John Michell described ‘dark stars’ whose light could not reach us, in a letter to Henry Cavendish that the Royal Society published. Royal Society

He worked out that a star as dense as the Sun but more than 500 times as wide would hold in its own light. Royal Society

He suggested that such a hidden body might still be found from the movements of bright bodies circling it. Royal Society

His idea was published more than 130 years before Einstein’s theory of gravity. Royal Society

Michell never used the words ‘black hole’, and nor did Einstein. Royal Society

Michell (1724–1793) was a British geologist and astronomer, counted among the fathers of seismology, the science of earthquakes. Britannica

Karl Schwarzschild

Schwarzschild found the first exact solution of Einstein’s equations of gravity, and laid the foundation of black hole theory. Britannica

In 1916 Karl Schwarzschild predicted that there could be collapsed stars that give out no radiation. Britannica

Schwarzschild was born in Frankfurt am Main in 1873 and died in Potsdam on 11 May 1916, after falling fatally ill while serving in the German army in the First World War. Britannica

A black-and-white photograph of a man in a dark suit with a moustache, sitting outdoors and writing in a notebook
Karl Schwarzschild, who found the maths behind the event horizon.Picture: Unknown photographer, Public domain, via Wikimedia Commons (cropped and resized)

Einstein’s doubts and Penrose’s proof

Einstein himself did not believe that black holes really exist. Nobel Prize, 2020

In January 1965, ten years after Einstein’s death, Roger Penrose proved that black holes really can form, and described them in detail. Nobel Prize, 2020

Penrose’s article is still regarded as the most important contribution to general relativity since Einstein. It won him half of the 2020 Nobel Prize in Physics. Nobel Prize, 2020

Who named them?

The name “black hole”: sources differ in what they say

  • The Royal Society says the term ‘black hole’ was coined by the American physicist John Archibald Wheeler in 1967. Royal Society
  • Britannica says Wheeler popularised the term black hole. Britannica

The Royal Society says Wheeler coined it; Britannica says he popularised it. Both put the name with Wheeler.

Wheeler (1911–2008) studied with Niels Bohr in Copenhagen and joined Princeton University in 1938. Britannica

With Charles Misner and Kip Thorne he wrote Gravitation (1973), a major textbook on Einstein’s relativity. Britannica

Stephen Hawking

The physicist Stephen Hawking proposed that black holes also slowly shrink, because they lose tiny amounts of energy, now called Hawking radiation. NASA, 10 questions

For most black holes we know about, shrinking noticeably would take much longer than the entire age of the universe. NASA, 10 questions

Hawking also proposed that many tiny primordial black holes, perhaps no heavier than an asteroid, might have formed in the Big Bang. Britannica

Stephen Hawking lost a bet, first placed in 1974, that Cygnus X-1 did not contain a black hole. NASA Chandra, 2011

Bigger and bigger

Even bigger black holes, about 10 billion Suns each, are inferred at the centres of the nearby galaxies NGC 3842 and NGC 4889. Britannica

Timeline

Next: myths and big questions →