An international collaboration of scientists has promised a “groundbreaking result” from a project on Wednesday that many expect will be the first-ever image of the edge of a black hole.
The Event Horizon Telescope project, which has for years been trying to capture the outline of the event horizon around the black hole at the centre of our galaxy, will broadcast its findings in simultaneous press conferences in cities around the globe.
If the group has succeeded, the results will mark a significant milestone in astrophysics that could challenge or confirm some of the major theories that underpin our understanding of the cosmos, including Albert Einstein’s theory of relativity.
Here’s why this matters.
What are black holes and why is it difficult to see them?
Black holes are born when massive stars die, collapsing in on themselves and creating a region where the force of gravity is so strong that nothing – stars, planets, gas, dust and even light – can escape and gets sucked in forever. They come in various sizes and are extremely dense.
Though scientists have been unable to photograph black holes, they have been able to hear them. When black holes collide into one another, they let off massive gravitational waves that have been detected by telescopes and interferometers at observatories in the U.S. and Italy.
Photos of black holes have been elusive for a number of reasons. One is that their gravitational pull makes it impossible for light to escape. They are also located extremely far away from Earth.
Given these difficulties, what scientists are actually trying to capture is the so-called “event horizon” – the border of a black hole and the point of no return beyond which everything gets sucked in forever. Though it is one of the most violent places in the universe, scientists do believe that radio telescopes can capture the event horizon by looking at its surroundings.
What is the Event Horizon Telescope project?
The project is interested in capturing the outlines of the event horizons of two specific black holes.
The first is called Sagittarius A* and is located 25,000 light-years away from Earth in the middle of our Milky Way Galaxy. Surrounded by bright gas and swirling material, Sagittarius A* has a mass that is equivalent to 4.1 million suns. The second black hole, M87, is 54 million light-years away from Earth in a neighbouring galaxy called Virgo A. It is estimated to weigh more than 6 billion suns.
Over five days in April 2017, the Event Horizon Telescope project pointed eight radio telescopes located in various cities across the globe to Sagittarius A*. When put together, the eight telescopes create “a virtual Earth-sized telescope,” according to the project.
Each of the telescopes collected reams of data that scientists hoped to synchronize and combine together to reveal the image. The data was sent to the U.S. and Germany, where it was set to be processed by computers called correlators.
So what does this all mean?
Beyond the unprecedented nature of a black hole image, scientists believe that it can help provide clarity on some of the debates in astro- and theoretical physics.
One of the aspects of a black hole that scientists are most eager to analyze is the shape of its silhouette.
Einstein’s theory of relativity predicts that it will be circular, while other theories predict that the shape will be “prolate,” meaning squashed along the vertical axis, or “oblate,” or squashed along the horizontal axis.
If the silhouette is prolate or oblate, the Event Horizon Telescope project said that this would not necessarily disprove the theory of relativity, but “would imply that we have more physics to understand."
