maybe the best account and video of first LIGO gravity wave 2015.09.14: The
New Yorker: Rich Murray 2016.02.11
http://rmforall.blogspot.com/2016/02/maybe-best-account-and-video-of-first.html


http://www.newyorker.com/tech/elements/gravitational-waves-exist-heres-how-scientists-finally-found-them

[ about 1 minute video, time slowed down about 100X -- the two black holes
spiral around each other, making 11 half-turns before merging suddenly
the black holes are invisible, so we see their twisted space-time showing
highly distorted swirling views of their far away galactic background --
this happened
1.3 billion years away ( 1.3 billion years ago -- our nearest neighbor
galaxy Andromeda is about 2.2 million lightyears away ( 2.2 million years
old from us -- our galaxy is about 0.1 million lightyears wide... ]

TODAY 10:30 AM
Gravitational Waves Exist: The Inside Story of How Scientists Finally Found
Them
BY NICOLA TWILLEY

"Just over a billion years ago, many millions of galaxies from here, a pair
of black holes collided.
They had been circling each other for aeons, in a sort of mating dance,
gathering pace with each orbit, hurtling closer and closer.
By the time they were a few hundred miles apart, they were whipping around
at nearly the speed of light, releasing great shudders of gravitational
energy.
Space and time became distorted, like water at a rolling boil.
In the fraction of a second that it took for the black holes to finally
merge, they radiated a hundred times more energy than all the stars in the
universe combined. They formed a new black hole, sixty-two times as heavy
as our sun and almost as wide across as the state of Maine.
As it smoothed itself out, assuming the shape of a slightly flattened
sphere, a few last quivers of energy escaped.
Then space and time became silent again."

[ Another source says they reached a top speed of half the speed of light
as they merged... ]

"On  Sunday, September 13th, Effler spent the day at the Livingston site
with a colleague, finishing a battery of last-minute tests.
“We yelled, we vibrated things with shakers, we tapped on things, we
introduced magnetic radiation, we did all kinds of things,” she said. “And,
of course, everything was taking longer than it was supposed to.”
At four in the morning, with one test still left to do — a simulation of a
truck driver hitting his brakes nearby — they decided to pack it in.
They drove home, leaving the instrument to gather data in peace.
The signal arrived not long after, at 4:50 A.M. local time, passing through
the two detectors within seven milliseconds of each other.
[ In Louisiana and in Oregon, 1,865 miles apart ]
It was four days before the start of Advanced LIGO’s first official run."

"Since the September 14th detection, LIGO has continued to observe
candidate signals, although none are quite as dramatic as the first event.
“The reason we are making all this fuss is because of the big guy,” Weiss
said. “But we’re very happy that there are other, smaller ones, because it
says this is not some unique, crazy, cuckoo effect.”


https://en.wikipedia.org/wiki/LIGO


"These sites are separated by 3,002 kilometers (1,865 miles).
Since gravitational waves are expected to travel at the speed of light,
this distance corresponds to a difference in gravitational wave arrival
times of up to ten milliseconds."

"After an equivalent of approximately 75 trips down the 4 km length to the
far mirrors and back again, the two separate beams leave the arms and
recombine at the beam splitter."

"Based on current models of astronomical events, and the predictions of the
general theory of relativity, gravitational waves that originate tens of
millions of light years from Earth are expected to distort the 4 kilometer
mirror spacing by about 10E−18 m, less than one-thousandth the charge
diameter of a proton. Equivalently, this is a relative change in distance
of approximately one part in 10E 21.
A typical event which might cause a detection event would be the late stage
inspiral and merger of two 10 solar mass black holes, not necessarily
located in the Milky Way galaxy, which is expected to result in a very
specific sequence of signals often summarized by the slogan chirp, burst,
quasi-normal mode ringing, exponential decay."


http://www.nature.com/news/einstein-s-gravitational-waves-found-at-last-1.19361

"One black hole was about 36 times the mass of the Sun, and the other was
about 29 solar masses.
As they spiraled inexorably into one another, they merged into a single,
more-massive gravitational sink in space-time that weighed 62 solar masses,
the LIGO team estimates."
[ So, 3 solar masses was radiated away as invisible gravitational energy --
about 5 % conversion of mass into pure energy... ]

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