When you look somewhere new, you see new things. To bad Joe Weber
didn't live to see this.
Brent
On 6/15/2016 7:25 PM, John Clark wrote:
After analyzing the data from LIGO's brief engineering run the
scientists there just announced they have found a second Black Hole
merger. A Black Hole of 14 solar masses merged with one of 8 solar
masses and produced a Black Hole of 21 solar masses and gravitational
waves with 1 solar mass of energy. It happened 1.4 billion light years
away, about the same distance as the first merger that was announced a
few months ago, but the signal was weaker because the Black Holes
involved were smaller (14 and 8 vs 36 and 29) and also because the
orbit of the Black Holes was more edge on relative to the Earth. Edge
on means the signal is weaker but it also means it's easier to
determine the spin, so unlike the first detection this time we can say
with certainty that at least one of the Black Holes was spinning. And
although weaker the signal lasted longer, almost a full second versus
a fifth of a second the first time because being smaller the holes
generated waves with higher frequencies that LIGO is more sensitive to.
And they're looking at at least one other suspected merger but they're
only 85% certain it's real and that's not good enough to claim
discovery, but there may be others so there may be a third
announcement before long. Not bad for observing for only 18 days. The
instrument was running at only one third power but that was still good
enough to determine that 2 mirrors 4 kilometers apart had changed
their distance by less than a billionth of a nanometer. I can't wait
for September when the 2 LIGOs get back online and are joined by a
third detector, VIRGO in Italy.
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.241103
John K Clark
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