It is time to stare into the abyss. The Event Horizon Telescope (EHT) has already made its first observations of the supermassive black hole at the centre of our galaxy, and the results 鈥� maybe even the first ever picture of a black hole 鈥� are expected next year.
Nine radio observatories around the world, including four in the US and one in Antarctica, make up the EHT. They all turn on simultaneously, combining to make a single, powerful 鈥渧irtual telescope鈥� spanning the planet.
In April 2017, the EHT looked at two supermassive black holes: Sagittarius A*, at the centre of the Milky Way and the closest one to us; and the much more massive black hole at the centre of nearby galaxy M87.
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The EHT collaboration鈥檚 images will look not like a sphere of darkness, but rather a banana of light. As the black hole rotates, it actually drags light along with it. This causes a bright crescent to appear on the side rotating towards us, juxtaposed with a dark shadow from the event horizon 鈥� the edge of the black hole itself.
The images will be the first ever ones of an event horizon, and the first direct proof that such a horizon exists, says collaboration member Heino Falcke at Radbout University Nijmegen in the Netherlands. We have hints from gravitational wave data (see 鈥�2019 Preview: Gravitational waves will be discovered every few weeks鈥�), but 鈥測ou can have something that almost quacks like a duck, but it is a pigeon in disguise鈥�, he says. 鈥淎ll of the evidence is indirect, and seeing is believing.鈥�
The observations could also help solve one of the greatest mysteries in modern physics: the fact that gravity, which acts mostly on very large scales, doesn鈥檛 seem to play well with quantum mechanics, which acts over small scales.
鈥淏y seeing this event horizon, that abstract problem becomes a physical, real problem in the real universe: you can point to a point in the sky and say, 鈥榯hat鈥檚 where it goes wrong,'鈥� Falcke says.
This article appeared in print under the headline 鈥淣ews Preview 2019: Seeing a black hole for real鈥�
