- Person
- Andrea Ghez
- Lived
- b. 1965
- Field
- Astronomy
- From
- American
The story
Andrea Ghez was born in New York City in 1965. Her father, the economist Gilbert Ghez, was born in Rome to a Jewish family of Tunisian and German origin that fled to the United States after Fascist Italy’s anti-Jewish laws of 1938; her mother came from an Irish Catholic family. Inspired by the Apollo Moon landings, she studied physics at MIT, earned a PhD at Caltech in 1992 and joined the University of California, Los Angeles.
The centre of the Milky Way is hidden from ordinary telescopes by dust, and although infrared light passes through, the Earth’s turbulent atmosphere blurs the crowded stars there into a smear. For decades astronomers had suspected that a supermassive black hole lay at the centre, near a radio source called Sagittarius A*, but the evidence was indirect. Ghez set out to settle the question by watching individual stars move.
From 1995 she used the ten-metre Keck telescopes in Hawaii, first with speckle imaging, which freezes the atmosphere’s distortion in thousands of short exposures, and then with adaptive optics, in which a flexible mirror cancels the blurring in real time. Year after year her group measured the stars’ positions. In 1998 they showed that stars near the centre move extraordinarily fast; in 2000 they measured their accelerations; and they eventually followed a star called S0-2 through a complete sixteen-year orbit. Applying Kepler’s laws, they found about four million solar masses packed into a region no bigger than our solar system, something only a black hole can explain. Reinhard Genzel’s team in Germany reached the same result independently.
The discovery made the Milky Way’s centre the best-studied black hole in the universe and a laboratory for testing Einstein’s general relativity, which her team did when S0-2 passed closest to the black hole in 2018. It underpins the modern view that most large galaxies are built around supermassive black holes. The adaptive optics methods she helped refine are now standard on the world’s largest telescopes, letting ground-based astronomers see almost as sharply as space telescopes. Ghez shared the 2020 Nobel Prize in Physics, the fourth woman to receive it, and has written a children’s book encouraging girls to become astronomers.
Why it matters
Ghez’s work proved that supermassive black holes are real and helped make adaptive optics a standard tool that gives telescopes on the ground far sharper vision.
About Andrea Ghez
UCLA astronomer who tracked stars racing around the Milky Way’s centre and proved a supermassive black hole sits there, pioneering sharp-imaging methods used across astronomy. Nobel Prize 2020.
Sources
- The Nobel Prize in Physics 2020, Popular information NobelPrize.org
- Andrea Ghez wins 2020 Nobel Prize in physics UCLA
- Andrea M. Ghez Wikipedia
Another act of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.