Apr 4, 2017 03:46 AM
https://aeon.co/essays/do-ripples-in-spa...of-gravity
EXCERPT: [...] In 2009, Afshordi, together with his colleagues Chanda Prescod-Weinstein and Michael Balogh, put forward a theory according to which black holes seed a long-range field that mimics dark energy. The field spills out from black holes and spans through the Universe. It’s an intriguing explanation for the origin of dark energy and, by Afshordi’s calculations, the number of black holes estimated to exist should create just about the right amount of field energy to fit the observations.
But Afshordi’s idea overthrows what physicists believed they knew about black holes. In Albert Einstein’s theory of general relativity, the event horizon of a black hole – the surface beyond which there is no escape – is insubstantial. Nothing special happens upon crossing it, just that there is no turning around later. If Afshordi is right, however, the inside of the black hole past the event horizon no longer exists. Instead, a Planck-length away from where the horizon would have been, quantum gravitational effects become large, and space-time fluctuations go wild. (The Planck length is a minuscule distance: about 10-35 metres, or 10-20 times the diameter of a proton.) It’s a complete break with relativity.
When he heard of the LIGO results, Afshordi realised that his so-far entirely theoretical idea could be observationally tested. If event horizons are different than expected, the gravitational-wave bursts from merging black holes should be different, too. Events picked up by LIGO should have echoes, a subtle but clear signal that would indicate a departure from standard physics. Such a discovery would be a breakthrough in the long search for a quantum theory of gravity. ‘If they confirm it, I should probably book a ticket to Stockholm,’ Afshordi said, laughing....
EXCERPT: [...] In 2009, Afshordi, together with his colleagues Chanda Prescod-Weinstein and Michael Balogh, put forward a theory according to which black holes seed a long-range field that mimics dark energy. The field spills out from black holes and spans through the Universe. It’s an intriguing explanation for the origin of dark energy and, by Afshordi’s calculations, the number of black holes estimated to exist should create just about the right amount of field energy to fit the observations.
But Afshordi’s idea overthrows what physicists believed they knew about black holes. In Albert Einstein’s theory of general relativity, the event horizon of a black hole – the surface beyond which there is no escape – is insubstantial. Nothing special happens upon crossing it, just that there is no turning around later. If Afshordi is right, however, the inside of the black hole past the event horizon no longer exists. Instead, a Planck-length away from where the horizon would have been, quantum gravitational effects become large, and space-time fluctuations go wild. (The Planck length is a minuscule distance: about 10-35 metres, or 10-20 times the diameter of a proton.) It’s a complete break with relativity.
When he heard of the LIGO results, Afshordi realised that his so-far entirely theoretical idea could be observationally tested. If event horizons are different than expected, the gravitational-wave bursts from merging black holes should be different, too. Events picked up by LIGO should have echoes, a subtle but clear signal that would indicate a departure from standard physics. Such a discovery would be a breakthrough in the long search for a quantum theory of gravity. ‘If they confirm it, I should probably book a ticket to Stockholm,’ Afshordi said, laughing....