Stephen Hawking's Legacy Today: How His Ideas Are Faring

Stephen Hawking died in 2018, but his ideas remain at the cutting edge of physics. This page tracks how his major contributions are faring in light of recent discoveries, and we update it as the science develops.

His area theorem confirmed (2021)

One of the most striking recent vindications came in 2021, when physicists used gravitational wave data from merging black holes to confirm Hawking's 1971 area theorem: the rule that the total area of black hole event horizons can never decrease. Detecting the ripples from two black holes merging into one, researchers showed the final horizon area exceeded the sum of the originals, exactly as Hawking predicted half a century earlier.

The first images of black holes (2019 and 2022)

In 2019 the Event Horizon Telescope produced the first ever direct image of a black hole, the supermassive giant M87*, and in 2022 it imaged Sagittarius A* at the centre of our own galaxy. While these do not test Hawking radiation directly, they confirmed in spectacular fashion the reality of the objects to which Hawking devoted his career, and matched the predictions of general relativity he had built upon.

The information paradox: still open

The black hole information paradox that Hawking launched in the 1970s remains one of the deepest unsolved problems in physics. Recent theoretical work, including ideas about "islands" and entanglement entropy, has made progress toward showing how information might escape an evaporating black hole after all, broadly supporting the view Hawking conceded to in 2004. The puzzle is not settled, but it continues to drive frontier research.

Hawking radiation in the laboratory

Because real black holes are too cold for their radiation to be detected, physicists have turned to "analogue" black holes, created using flowing fluids, sound waves or light, to look for the effect. Several experiments have reported results consistent with Hawking radiation, strengthening confidence in the prediction even though a real black hole has never been seen to evaporate. This remains why he never won a Nobel Prize.

A living legacy

Taken together, the picture is of a body of work that has aged remarkably well. His mathematical results are being confirmed, the objects he studied are now being photographed, and the puzzles he posed still define the frontier. Few physicists leave a legacy so alive. For the foundations behind these developments, explore his key scientific papers.

References

Key sources for the developments described on this page:

1. Isi, M., Farr, W. M., Giesler, M., Scheel, M. A. and Teukolsky, S. A. "Testing the Black-Hole Area Law with GW150914." Physical Review Letters 127, 011103 (1 July 2021). DOI: 10.1103/PhysRevLett.127.011103. The study confirmed Hawking's area theorem from gravitational-wave data, with agreement at the 95 to 97 percent level depending on the model used.
2. Hawking, S. W. "Gravitational Radiation from Colliding Black Holes." Physical Review Letters 26, 1344 to 1346 (1971). DOI: 10.1103/PhysRevLett.26.1344. The paper in which the area theorem was introduced.
3. Event Horizon Telescope Collaboration. "First M87 Event Horizon Telescope Results." Astrophysical Journal Letters (2019): the first image of a black hole, of M87*.
4. Event Horizon Telescope Collaboration. "First Sagittarius A* Event Horizon Telescope Results." Astrophysical Journal Letters (2022): the first image of the black hole at the centre of the Milky Way.
5. Hawking, S. W., Perry, M. J. and Strominger, A. "Soft Hair on Black Holes." Physical Review Letters 116, 231301 (2016). DOI: 10.1103/PhysRevLett.116.231301.

This page is updated as the science develops; the "last reviewed" date above indicates when it was last checked.