‘If we knew what it was we were doing, it would not be called research, would it?’ said Albert Einstein. Well, he must have figured something out, because scientists have glimpsed the event horizon of a black hole for the very first time. The world-first image, released in April 2019, is the result of a seven-year project that linked telescopes across the world to create what scientists have said was ‘a dish the size of the planet’. All we’ve had up until now is artists’ impressions, but the fact that the real image matches the predictions so closely is a confirmation of Einstein’s theory of general relativity. Let’s drink a toast to the man – drei stein, swei stein, ein stein! (Photo montage by L.J. May S/S Channel7)
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A BLACK HOLE IS A TUNNEL AT THE END OF LIGHT!
‘We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet.’ – Stephen Hawking.
CAPTURING THE EVENT HORIZON!
‘It is said that fact is sometimes stranger than fiction, and nowhere is that more true than in the case of black holes. Black holes are stranger than anything dreamed up by science fiction writers.’ – Stephen Hawking.
During NATIONAL SCIENCE WEEK in Australia we explore the latest in various disciplines and congratulate those who have made a significant
contribution to our body of knowledge. The black hole image released by the Event Horizon Telescope (EHT) team on Wednesday, 10 April 2019 is up there with the best and most important of scientific discoveries.
Scientists announced that they had glimpsed and photographed a black hole for the very first time. The world-first image showed the super-massive black hole, known as M87,
at the centre of Virgo A, a neighbouring galaxy to our own Milky Way. Until now, all images of a black hole have been artists’ impressions, so this was a huge day in astrophysics.
The Scientists announced their findings at one of seven simultaneous press conferences. France Cordova, director of the US National Science Foundation said: ‘We've been studying black holes so
long that sometimes it's easy to forget that none of us has actually seen one.’
‘This is a huge
day in astrophysics. We're seeing the unseeable.’
M87 sits 55 million light-years from Earth and is 6.5 billion times heavier than
the Sun. Its event horizon is spherical in shape and about three times bigger than the path Pluto traces around the Sun. Even though it is huge, it is still incredibly difficult to see. See a M87 Black Hole Size Comparison https://xkcd.com/2135.
Observing black holes is a notoriously difficult challenge because their gravitational pull is so strong that nothing – not even light – can escape once it crosses the event horizon: the point of no return. April’s historic
image is the result of decades of theoretical predictions and technical advances. The image matches predictions so closely, it is a confirmation of Einstein’s theory of general relativity.
‘This is an extraordinary scientific feat accomplished by a team of more than 200 researchers,’ said Dr Sheperd Doeleman from the Harvard-Smithsonian Centre for Astrophysics. ‘We
have achieved something presumed to be impossible just a generation ago.’
Dr Doeleman pioneered the instrument that made
it all possible: the Event Horizon Telescope (EHT), the result of a seven-year project linking telescopes across the world to create ‘a dish the size of the planet’.
One of the telescopes in the network is the James Clerk Maxwell Telescope on top of Mauna Kea peak in Hawaii, where Australian, Jessica Dempsey, is deputy director. By combining results from nine separate dishes,
scattered from Antarctica to Europe, Dr Dempsey and her colleagues can create a virtual telescope 9,000 kilometres in diameter, making it the world's biggest camera.
‘We’ve made a dish the size of the planet,’ Jessica told ABC’s Catalyst program earlier this year. ‘To give you an idea of how small a thing you can see, if you're sitting in a pub in Perth, you would be able
to see a guy sitting in the pub in Sydney, 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. (Go to https://iview.abc.net.au/show/catalyst for
Their combined observing power has been trained on two super-massive black holes, including the one
in the centre of our own Milky Way galaxy, Sagittarius A*. This is situated 26,000 light-years from Earth and is 4 million times the mass of our Sun, but by super-massive black hole standards, it's pretty small. Researchers say they are still
analysing data from Sagittarius A*.
Over several nights in April 2017, the EHT turned its dishes towards M87 and collected vast
quantities of data. The files were so large they were too big for the internet, and team members had to carry their findings around the world on hard drives. After two years of analysis, the EHT team called their global press conference.
Nobody outside the project knew exactly what they would be announcing, but they had been told that it was ‘a groundbreaking result. Space and physics enthusiasts, both professional
and non-professional, went into meltdown. (Some information for nerds: the finding is also described in a series of six research papers, all published in a special issue of Astrophysical Journal Letters.)
What exactly are
we looking at? The bright ring in the image is caused by the incredible pull the black hole exerts on nearby matter. It's surrounded by a swirling disc of gas, which gets superheated and emits bright radio waves as it accelerates towards the event horizon
– getting very, very close to the speed of light.
Einstein's theory of general relativity first predicted the existence of black holes,
as well as mapping out how such heavy objects would warp the fabric of space-time and bend the path of light.
University of Queensland astrophysicist Professor Tamara Davis explains: ‘You can see that one side of that ring is brighter than the other, and that's the side that's coming towards us as the whole thing spins. That was also predicted by relativity – that
if it was spinning (and most things do tend to spin), then it would have one side that was brighter than the other.’
those mind-bending ideas, Professor Davis said, that probably explain why we can see the orange ring in all its glory. Although the blazing, spinning disc of material passes behind the black hole, from our perspective, the light actually curves right around
the black hole – so that telescopes on Earth can still catch it. ‘It gets emitted and bent, forming the visible ring that we can see, with the black hole in silhouette and the ring around it,’ she said.
public broadcaster, the ABC, is all over the discovery. Thanks to the ABC for most of the information given in the article above. Go to the ABC’s news and science websites listed below to find more about black holes and this big event horizon:
STEPHEN HAWKING DIED AT THE AGE OF 76 (SNIFFLE!)
Theoretical Physicist, Cosmologist and Genius, STEPHEN HAWKING, passed away at Cambridge on Wednesday, 14 March 2018, and most people across the world who knew of his work were sad.
Professor Hawking was to physics and exploring the universe as Sir David Attenborough is to informing us about the natural world, and he is still sorely missed.
he was obsessed by cosmology in general, and black holes in particular, Stephen once said to his family, ‘It would not be much of a universe if it wasn’t home to the people you love.’
Stephen Hawking was an English theoretical physicist, cosmologist, author and Director of Research at the Centre
for Theoretical Cosmology within the University of Cambridge. His scientific works included a collaboration with Roger Penrose on gravitational singularity theorems in the framework of general relativity and the theoretical prediction that black holes emit radiation, often
called Hawking radiation.
It’s astonishing that Stephen had a career at all, given that as a graduate student in 1963,
when he was only 21, he was diagnosed with a rare early-onset slow-progressing form of motor neurone disease (also known as amyotrophic lateral sclerosis or ‘ALS’ and Lou Gehrig's disease), that gradually paralysed him over the decades.
Even after he lost the power of speech, he was still able to communicate through a speech-generating device, initially through use of a hand-held switch, and eventually by using a single cheek muscle.
Not only did Stephen refuse to die within a few years of his diagnosis as predicted, he became a pop culture icon and achieved commercial success with works of popular science in
which he discussed his own theories and cosmology in general. His book, A Brief History of Time, appeared on the British Sunday Times best-seller
list for a record-breaking 237 weeks.
Visit Stephen Hawking’s official website at http://www.hawking.org.uk (yes, it’s still going), and go to the menu where
you can access more about Stephen, including lectures, publications, books, films, videos, TV series, and a photo gallery.