HEAPOW: Gravity's Echoes? (2016 Dec 19)

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bystander
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HEAPOW: Gravity's Echoes? (2016 Dec 19)

Post by bystander » Mon Dec 19, 2016 6:24 pm

Image HEAPOW: Gravity's Echoes? (2016 Dec 19)

Black holes are regions of space bounded by an "event horizon" beyond which nothing can escape. Any object or signal of any kind that passes through the event horizon is forever removed from communicating in any way with the surrounding Universe, according to Einstein's theory of gravity. Einstein's theory also predicts the existence of gravitational radiation, waves in spacetime produced by the acceleration of mass. The direct detection of gravitational radiation from merging black holes by the Laser Interferometer Gravitational Wave Observatory (LIGO) was spectacular confirmation of Einstein's predictions. This discovery also opened an entirely new window on the Universe and allows important new tests of our understanding of the structure of the event horizon - whether it's described by the relatively simple idealized spacetime of General Relativity, or if it's a seething region of "firewalls" or "fuzzballs". A new analysis of the LIGO merger events detected so far seems to suggest that strange things may be afoot near the event horizon. A careful study of the LIGO signals seems to have found evidence of "echoes" of the gravitational wave signal which are apparently reflected somehow from the horizon - something that wouldn't be allowed by General Relativity. If true, this may suggest that black holes are surrounded by a firewall of high-energy particles, a direct contradiction of general theory. Was Einstein both wrong and right?

Nature: LIGO black hole echoes hint at general-relativity breakdown
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neufer
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Re: HEAPOW: Gravity's Echoes? (2016 Dec 19)

Post by neufer » Mon Dec 19, 2016 7:49 pm

https://en.wikipedia.org/wiki/Echo_(mythology) wrote: <<In Greek mythology, Echo ( Greek: Ἠχώ, from ἦχος (ēchos), "sound") was an Oread who resided on Mount Cithaeron. Zeus loved consorting with beautiful nymphs and often visited them on Earth. Eventually, Zeus's wife, Hera, became suspicious, and came from Mt. Olympus in an attempt to catch Zeus with the nymphs. Echo, by trying to protect Zeus, endured Hera's wrath, and Hera made her only able to speak the last few words spoken to her. So when Echo met Narcissus and fell in love with him, she was unable to tell him how she felt and was forced to watch him as he fell in love with himself. When Narcissus died, wasting away before his own reflection, consumed by a love that could not be, Echo mourned over his body. When Narcissus, looking one last time into the pool uttered, "Oh marvellous boy, I loved you in vain, farewell", Echo too chorused, "Farewell." Eventually, Echo, too, began to waste away. Her beauty faded, her skin shrivelled, and her bones turned to stone. Today, all that remains of Echo is the sound of her voice.>>
Art Neuendorffer

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