The image of a fiery ring, framing a black hole from the distant M87 galaxy, has already been hailed as an iconic moment of scientific discovery.
Event Horizon Telescope (EHT) has just unveiled the image of the black hole. The centre’s director, Shepherd Doeleman, described the capture as “an extraordinary scientific feat”.
“We have achieved something presumed to be impossible just a generation ago,” he said.
“Breakthroughs in technology, connections between the world’s best radio observatories, and innovative algorithms all came together to open an entirely new window on black holes.”
The photo is both an incredible technical feat and exciting for scientists for the new possibilities it opens up.
— BBC Breaking News (@BBCBreaking) April 10, 2019
Event Horizon Telescope captured “a knot you can’t untie”
Eight telescopes observed the M87 galaxy, which is 54 million light-years from earth, for five days back in April 2017 to capture the image. The event horizon captured is a zone where an incredible amount of mass has been squeezed into a tight space. As a result, the force of gravity there is so overwhelming no light can escape from it.
In a mind-bending twist, the event horizon is manifest as the “sudden absence of light” according to Feryal Özel, one of the EHT team members.
“We have gone right to the edge of the event horizon, and seen the point of no return,” said EHT researcher Avery Broderick. “This is an extraordinary moment in science.”
The painstaking process of capturing the image also ties in with sections of Albert Einstein’s theory of gravity. Previously, scientists had uncovered gravitational waves caused by the collision of black holes and the gravitational effect they have on neighbouring planets. But a photo had remained elusive until the EHT’s breakthrough.
— Albert Einstein (@AlbertEinstein) April 10, 2019
Einstein’s theories and the newly photographed black hole
Doeleman said that black holes have captured the popular imagination because they are so mysterious and foreign.
“Einstein himself wasn’t really sure that black holes existed,” he said. “The fact is we’re drawn to things that we don’t understand, because we yearn to know more. They’re terrifying, but we can’t look away.
“And the reason they’re terrifying, the reason this is an important image, is because when you look into the middle of it, you realise that we’ve theorised about these monsters being out there, and now we know they are — and what’s more, now we see them.
“This is the only place in the universe where the cosmos ties a knot you can’t untie. Every other place in the universe you can, in theory, come back from, but not there.”
Above: This infographic shows a simulation of the outflow from a black hole (in bright red) and simulates three possible shapes of the shadow of the event horizon. Credit: ESO/N. Bartmann/A. Broderick/C.K. Chan/D. Psaltis/F. Ozel
Photographing the black hole seemed an impossible goal
The project was also a remarkable collaborative achievement. More than 200 scientists worked to focus the telescopes, located in Hawaii, Mexico, the mountains of Arizona, the deserts of Chile and Antarctica, to the M87 galaxy.
Dr Jessica Dempsey, Deputy Director of one of the telescopes involved, the James Clerk Maxwell Telescope at the Mauna Kea peak in Hawaii, said the combined camera formed by the network of telescopes would be able to see a man on the East Coast of Australia from its West Coast. “Not only would you be able to see him, you’d be able to see his eye colour, and you’d be able to see the brand of beer he was drinking,” she said.
The telescope network across the world also had to be synced to a billionth of a second.
“We are stacking impossible task on top of impossible task and this shouldn’t work,” she said.
Above: A previous image of a supermassive black hole in the Milky Way galaxy. Like all photos of black holes before the EHT image, this is a simulation. Photo credit: X-ray: NASA/CXC/UCLA/Z.Li et al; Radio: NRAO/VLA
The black hole that can be seen in the EHT’s image is around 7 billion times the mass of the earth’s sun. Its radius is 130 times that of the Earth’s entire orbit.
Yet given the immense distance between the black hole and earth, capturing the giant black hole has been likened to trying to spot an orange on the moon.
The greatest logistical challenge of all, however, may be the nature of the subject itself. “A black hole, if you looked at it naked … would be invisible,” Doeleman explained. “It’s nature’s most amazing invisibility cloak.”
A paradox means that the gas and other matter attracted to it heats up to hundreds of billions of degrees, forming the visible fiery ring around the otherwise invisible hole.
Header image credit: EHT Collaboration