How one man first predicted what a black hole would look like
Published : Saturday, 13 April, 2019 at 1:53 PM Count : 353
The world's very first simulation of a black hole created 40 years ago was surprisingly close to an image of the real thing released to acclaim by scientists yesterday, it has been revealed.
The image - created by Dr Jean-Pierre Luminet, then a young researcher at The French National Centre for Scientific Research (CNRS) - had a worldwide impact at the time of its release in 1979.
It was particularly revolutionary as the existence of black holes was still highly theoretical at the time and a point of much debate among the scientific community.
The simulation shares a number of characteristics with the image released yesterday by the team behind the Event Horizon Telescope (EHT), the first time a direct observation of a black hole's event horizon has been captured.
Dr Luminet's picture is not an artist's impression but is instead based on the then supposed physical properties of a black hole and its gas disc - including its rotation rate and temperature - and on Einstein's general theory of relativity.
Using computer data, Dr Luminet drew several thousand black dots on a white sheet by hand. He then took a photographic negative to produce the final image.
He envisioned a black circle, which had not yet become known as the shadow of the black hole as it is today, in the centre of a glowing accretion disc with one side clearly brighter than the other.
This is because there are two effects that shift the radiation that reaches us from the disc, the Einstein and Doppler effects.
The Einstein effect describes how the gravitational field of a black hole distorts the light that reaches us.
This makes light from the part of the accretion disc behind the black hole appear as visible above it.
The Doppler effect describes how gas racing around the black hole toward us appears brighter, an effect caused by the rotation of the accretion disc around the black hole.
These are all characteristics that can be found in the real image obtained forty years later by the EHT, indicating just how accurate this first simulation was.
These effects can be seen even more clearly in an updated version of the simulation that Dr Luminet and his team released in 1991 with added orange colouration highlighting Doppler distortions and asymmetries.
Scientists yesterday lifted the veil on the first images ever captured of a black hole’s event horizon.
In a highly-anticipated string of press conferences held simultaneously around the world on Wednesday, the team behind the EHT revealed the findings from their first run of observations.
Using a ‘virtual telescope’ built from eight radio observatories positioned at different points on the globe, the international team has spent the last few years probing Sagittarius A*, the supermassive black hole at the heart of the Milky Way, and another target called M87 in the Virgo cluster of galaxies.
While black holes are invisible by nature, the ultra-hot material swirling in their midst forms a ring of light around the perimeter that reveals the mouth of the object itself based on its silhouette. This boundary is known as the event horizon.
'We have seen what we thought was unseeable,' EHT Director Sheperd Doeleman said as he introduced the glowing orange ring that is the object at the center of Messier 87 (M87) – and our first direct look at a black hole.
The breakthrough adds major support for Einstein’s theory of General Relativity and could help to answer longstanding questions on the nature of black holes.-Daily Mail