
About the LIGO Gravitational-Wave Rumor - subnaught
http://www.skyandtelescope.com/astronomy-news/about-this-weeks-gravitational-wave-rumor/?utm_source=newsletter&utm_campaign=sky-mya-nl-160115&utm_content=813396_SKY_HP_eNL_160115&utm_medium=email
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mhw
The bit I found most interesting:

"The current excitement could easily be a false alarm. Even if LIGO has a
promising signal, it may be a false test signal planted as a drill. It's been
done before, in 2010 near the end of LIGO's last pre-upgrade run. Three
members of the LIGO team are empowered to move the mirrored blocks by just the
right traces in just the right way. Only they know the truth, and the test
protocol is that they not reveal a planted signal until the collaboration has
finished analyzing it and is ready to publish a paper and hold a press
conference. “Blind tests” like this are the gold standard in all branches of
science."

Getting to the point of publishing a paper and holding a press conference
seems like a lot of potentially wasted effort on a fire-drill type exercise.
Presumably there are reasons why they wouldn't just let everyone know that it
was a drill when they'd all decided on a conclusion? I realise that I'm
assuming that the point of drawing that conclusion is much earlier than
completing the paper as well, which may not be true.

~~~
VLM
Its probably poor phrasing in the article. The key is its event based (more or
less) and they don't reveal until after all analysis is done.

So analysis complete we have X events at a SNR of 3 dB, Y events at a SNR of 2
dB, etc. Then and only then do the blind test dudes reveal "ah well all X
events at a SNR of 3 dB were fake, and one of the Y events was fake, and you
missed detecting one of the Y level events but the other 42 results were
real."

We did this a lot in quantitative chemical analysis lab, it kind of spoils the
point of the lab session if the TAs tell you the percentage iron in the sample
before you start to test it, or while you're evaluating the test run results.

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ccozan
From the comments: "... how much noise exists in the measurement environment?
I find it difficult to believe something even as mundane as a minuscule
earthquake or similar ground noise wouldn’t cause orders of magnitude more of
a signal and therefore swamp out any meaning information"

This is also the first thing that came to my mind. How do the filter noise? Or
are we missing something that is not described in the article?

And secondly, why not putting ( teoretically) this lasers into space? Aside
the solar radiation/wind, not much would interfere if put around the Lagrange
points.

~~~
Steuard
As I understand it, this is one of the main reasons that there are _two_
detectors thousands of miles apart, in Washington and Louisiana. There will be
a whole lot of false alarms at each one separately, but it's extremely
unlikely that precisely matching earthquakes will occur at both locations at
once. (They have other very sophisticated ways of isolating the system from
outside noise, too, of course. But I don't think the experiment would be
viable without the two location filter.)

As for space, the LISA project has been trying to get funding for years. (The
preliminary "LISA Pathfinder" mission launched on Dec. 3, so there's finally
some real progress on this: [http://sci.esa.int/lisa-
pathfinder/](http://sci.esa.int/lisa-pathfinder/))

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basicplus2
my intuition says this is impossible to detect as if space time is bent then
all the equipment and our reality is bent along with it and thus we will be
none the wiser.... ie we might be inside a bent reality but we and all our
sensing equipment will still sense everything as straight.

~~~
jerf
It's not bent the same in all directions. You can detect the difference in
different directions, which is what LIGO does.

Your point, by the way, was hashed out in the early 1900s as part of the
development of modern relativity. Physicists were well aware of the problem
back then, and that's part of why it's so interesting and important that the
speed of light turns out to be a constant.

