The first image of a black hole, captured in 2019 by the team of Greek astronomer Dimitrios Psaltis, has revealed more support for Albert Einstein’s theory of general relativity.
The image measures the Messier87 (M87) black hole which is 40 billion km across – three million times the size of the Earth – and has been described by scientists as “a monster.”
The black hole is 500 million trillion kilometers away from the earth and was photographed by a network of eight telescopes across the world, coordinated by the Event Horizon Telescope (EHT) project. The EHT is a consortium of more than 200 scientists who have been consulting on the massive project for about two decades.
Psaltis, a professor of astronomy and physics at the University of Arizona, is the EHT’s project scientist.
His team have made the first measurement of the size of a black-hole shadow. Based on an analysis of M87’s shadow, the EHT researchers have now conducted a unique test of general relativity, deepening understanding about the unusual properties of black holes and ruling out many alternatives.
“Together with gravitational wave observations, this marks the beginning of a new era in black hole astrophysics,” said Psaltis.
Despite its success, Albert Einstein’s theory remains mathematically irreconcilable with quantum mechanics, the scientific understanding of the subatomic world.
Testing general relativity is important because the ultimate theory of the Universe must encompass both gravity and quantum mechanics.
“We expect a complete theory of gravity to be different from general relativity, but there are many ways one can modify it,” said Psaltis.
“We found that whatever the correct theory is, it can’t be significantly different from general relativity when it comes to black holes.”
“We really squeezed down the space of possible modifications.”
The Greek astronomer was born in Serres, a town in northern Greece in 1970. He studied physics at the University of Thessaloniki. He graduated in July of 1992 and started his graduate studies in the astronomy department of the University of Illinois.
In 1997, Psaltis moved to the Harvard-Smithsonian Center for Astrophysics, as a Smithsonian Postdoctoral Fellow. He continued as a postdoctoral researcher at MIT, and for two years as a long-term member at the Institute of Advanced Study, in Princeton, NJ.
In January 2003, he began work as part of the physics and astronomy faculty at the University of Arizona.