Re: LIGO is coming into operation in stages

Ken S. Tucker wrote: 
Sam Wormley wrote:

Ken S. Tucker wrote:

Sam Wormley wrote:


LIGO is coming into operation in stages
 http://www.edu-observatory.org/physics-faq/General/open_questions.html


Do gravitational waves really exist? If so, can we detect them? If
so, what will they teach us about the universe? Will they mainly come

from expected sources, or will they surprise us? 

 Perhaps the most ambitious physics experiments of our age are the
 attempts to detect gravitational waves. Right now the largest
 detector is LIGO--the the Laser Interferometer Gravitational-Wave
 Observatory.  This consists of two facilities: one in Livingston,
 Louisiana, and one in Hanford, Washington. Each facility consists of
 laser beams bouncing back and forth along two 4-kilometer-long tubes
 arranged in an L shape. As a gravitational wave passes by, the tubes
 should alternately stretch and squash--very slightly, but hopefully
 enough to be detected via changing interference patterns in the laser
 beam.

 LIGO is coming into operation in stages. The first stage, called LIGO
 I, is supposed to allow detection of gravitational waves made by
 binary neutron stars within 65 mega light years of us. These binaries
 emit lots of gravitational radiation, spiral into each other, and
 eventually merge. In the last few minutes of this process you've got
 two objects heavier than the sun whipping around each other about 100
 times a second, faster and faster, and they should emit a "chirp" of
 gravitational waves increasing in amplitude and frequency until the
 final merger. It's these "chirps" that LIGO is optimized for
 detecting. Later, in LIGO II, they'll try to boost the sensitivity to
 allow detection of inspiralling binary neutron stars within 1000 mega
 light years of us.

 To give you an idea of what these distances are like: the radius of
 the Milky Way is about 50,000 light years. The distance to the
 Andromeda galaxy is about 2.3 mega light years. The radius of the
 "Local Group" consisting of three dozen nearby galaxies is about 6
 mega light years. The distance to the "Virgo Cluster", the nearest
 large cluster of galaxies, is about 50 mega light years. The radius
 of the observable universe is roughly 10,000 mega light years. So, if
 everything works as planned, we'll be able to see quite far with
 gravitational waves.

 However, binary neutron stars don't merge very often! The current
 best guess is that with LIGO I we will be able to see such an event
 somewhere between once every 3000 years and once every 3 years. I
 know, that's not a very precise estimate! Luckily, the volume of
 space we survey grows as the cube of the distance we can see out to,
 so LIGO II should see between 1 and 1000 events per year.

 The really scary thing is how good LIGO needs to be to work as
 planned. Roughly speaking, LIGO I aims to detect gravitational waves
 that distort distances by about 1 part in 10^21. Since the laser
 bounces back and forth between the mirrors about 50 times, the
 effective length of the detector is 200 kilometers. Multiply this by
 10^-21 and you get 2 x 10^-16 meters. By comparison, the radius of a
 proton is 8 x 10^-16 meters! So, we're talking about measuring
 distances to within a quarter of a proton radius! And that's just
 LIGO I. LIGO II aims to detect waves that distort distances by a mere
 2 parts in 10^23, so it needs to do 50 times better.

See: http://www.edu-observatory.org/physics-faq/General/open_questions.html 


Hey Sam
What would be super cool is to see some thumps on
LIGO just before a Gamma Ray Burst!
Ah well, I live in fiction.


Good shot at it coming soon from a galaxy near you! 


Yes, but allow me to conflate.

Assuming the GRB (Gamma Ray Burst) follows as a
result of spiralling of n-stars to a merger that terminates
the relative spiral orbiting, then we should expect a
"thumping" on LIGO just prior to a GRB, when the n-star
merger occurs.

I'm not joking. GRB's are detected independantly by
other EMR detection apparatus. It would be an absolute
confirmation of the LIGO apparatus and the existence and
detection of g-waves if that system could predict a GRB,
even a few seconds before the GRB's hit Earth.

What do you think?
Ken


  If the source of such an event can be identified with indications
  two or more gravity wave detectors correlating with photons and or
  neutrinos--there would be a lot of excited researchers!

.

Relevant Pages

  • Re: LIGO is coming into operation in stages
    ... LIGO is coming into operation in stages. ... is supposed to allow detection of gravitational waves made by ... The distance to the Andromeda galaxy is about 2.3 mega light years. ... The distance to the "Virgo Cluster", the nearest large cluster of galaxies, is about 50 mega light years. ...
    (sci.physics)
  • Re: LIGO is coming into operation in stages
    ... >>> attempts to detect gravitational waves. ... >>> LIGO is coming into operation in stages. ... >>> binary neutron stars within 65 mega light years of us. ... >>> allow detection of inspiralling binary neutron stars within 1000 mega ...
    (sci.physics)
  • LIGO claims in recnt news.
    ... journals of how the NON detection of "gravitational waves" by LIGO are ... Unless and until LIGO produces a few "real" events traceable directly to ... "gravitational wave" detection. ... Anyone with a knowledge of the history of Physics should look up the N ray ...
    (sci.physics.research)
  • Re: LIGO is coming into operation in stages
    ... > LIGO is coming into operation in stages ... > attempts to detect gravitational waves. ... > binary neutron stars within 65 mega light years of us. ... > that distort distances by about 1 part in 10^21. ...
    (sci.physics)
  • Re: LIGO claims in recnt news.
    ... journals of how the NON detection of "gravitational waves" by LIGO are ... Unless and until LIGO produces a few "real" events traceable directly to ... "gravitational wave" detection. ... Anyone with a knowledge of the history of Physics should look up the N ray ...
    (sci.physics.research)
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