blockmemento

// block 571029 · science · 10 April 2019

The first image of a black hole

The moment this block marks: the start of the coordinated EHT press conferences, 09:00 in Washington and 15:00 in Brussels, 10 April 2019, 13:00:00 UTC. The first block mined after it is block 571,029, 10 April 2019, 13:01:35 UTC.

No telescope on Earth is large enough, on its own, to see a black hole. The Event Horizon Telescope joined eight radio observatories, on volcanoes in Hawaii and Mexico, on mountains in Arizona and the Spanish Sierra Nevada, in the Atacama Desert of Chile and at the South Pole, into a single instrument the size of the planet. In 2017 they observed together at a wavelength of 1.3 millimetres, and the petabytes of data they recorded were flown to supercomputers in Germany and the United States to be combined.

Two years later, on 10 April 2019, the collaboration presented the result at six press conferences held at the same moment, in Washington, Brussels, Santiago, Shanghai, Taipei and Tokyo. The image showed a ring of light around a dark centre: the shadow of the black hole at the heart of the galaxy Messier 87, 55 million light-years away, with a mass 6.5 billion times that of the Sun. Its appearance agreed closely with the predictions of general relativity.

“We have taken the first picture of a black hole,” said Sheperd Doeleman, director of the project, crediting a team of more than 200 researchers. Six papers describing the work appeared the same day in The Astrophysical Journal Letters.

The first block mined after the conferences opened, block 571,029, came a minute and a half later, as the speakers were beginning, and a few minutes before the press releases went out at 13:07 UTC. Its hash, like every hash, can be checked on any node.

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