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Black holes and revelations

24 Jun 2019, 08:30 UTC
Black holes and revelations
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Science journalist Ron Cowen’s brief but rewarding book – Gravity’s Century: From Einstein’s Eclipse to Images of Black Holes – celebrates two great scientific events concerning gravity that occurred almost exactly a century apart. The first was the November 1919 confirmation of Albert Einstein’s general theory of relativity. This was made possible by British telescopic observations from West Africa and Brazil of a solar eclipse in May 1919, which revealed the deflection of light rays from the Hyades star cluster by the gravity of the Sun. These had been organized by Astronomer Royal Frank Dyson with Arthur Eddington. Analysis of the data proved tricky – hence the delay in announcing the result until a joint meeting of the Royal Society and the Royal Astronomical Society in November of that year. The second event was the 2017 observation, publicised in 2019, by the worldwide Event Horizon Telescope (EHT) of a phenomenon long predicted by general relativity: a black hole. Located 55 million light-years from Earth, in the centre of the Messier 87 galaxy of the Virgo galaxy cluster, the black hole has a mass 6.5 billion times that of the Sun, with an uncertainty of 0.7 billion solar masses. The EHT’s ...

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