“The black hole is not the event horizon, it’s something inside. However, the observations do not yet reveal anything about the black hole’s inscrutable interior. Scientists are also hoping to understand more about the origin of jets of radiation that are blasted out from the poles of some black holes at close to the speed of light, creating brilliant beacons that can be picked out across the cosmos. The observations also provide one of the most stringent tests to date of Einstein’s theory of general relativity: this predicts a rounded shape of the black hole’s halo, in line with what EHT has observed. The observations are already giving scientists new insights into the weird environment close to black holes, where gravity is so fierce that reality as we know it is distorted beyond recognition.Īt the event horizon, light is bent in a perfect loop around the black hole, meaning if you stood there you would be able to see the back of your own head. This meant waiting for half a year for the South Pole data, which could only be shipped out at the end of Antarctic winter. The sheer volume of data generated was also unprecedented – in one night the EHT generated enough data to fill half a tonne of hard drives. “We got super lucky, the weather was perfect,” said Ziri Younsi, a member of the EHT collaboration who is based at University College London. And, on one night in April 2017, everything came together. Observations at the different sites were coordinated using atomic clocks, called hydrogen masers, accurate to within one second every 100 million years. The success of the project hinged on clear skies on several continents simultaneously and exquisite coordination between the eight far-flung teams. “We hope to get that very soon,” said Doeleman. The collaboration is still working on producing an image of the Milky Way’s black hole. The second target, which yielded the image, was a supermassive black hole in the galaxy M87, into which the equivalent of 6bn suns of light and matter has disappeared. First was Sagittarius A*, the black hole at the centre of the Milky Way, which has a mass of about 4m suns. When observations were launched in 2017, the EHT had two primary targets. The EHT achieved the necessary firepower by combining data from eight of the world’s leading radio observatories, including the Atacama Large Millimetre Array (Alma) in Chile and the South Pole Telescope, creating an effective telescope the size of the Earth. This was once thought to be an insurmountable challenge. A lot of this material is destined for oblivion, although some of it is ejected as powerful jets of radiation.īut black holes are so small, dark and distant that observing them directly requires a telescope with a resolution equivalent to being able to see a bagel on the moon. This is the point at which escaping would require something to travel at faster than the speed of light – which as far as we know nothing does – so it is the point of no return.īlack holes are surrounded by an accretion disk of dust and gas, orbiting at close to the speed of light. The edge of the black hole is defined by its so-called event horizon. The equations predicted that, beyond a certain threshold, when too much matter or energy is concentrated in one place, space and time collapse, leaving behind a sinkhole through which light and matter can enter but not escape.Īt first these were thought to be mathematical oddities, rather than real astronomical objects, but in the past century overwhelming evidence has confirmed that black holes are out there. Black holes were first predicted by Einstein’s theory of general relativity, which reimagined gravity as the warping of space and time by matter and energy.
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