Question about LIGO theory (for the physicists out there)
14 Nov 2004 0:00:15 UTC
Topic 187084
(moderation:
If gravitational waves distort spacetime (which LIGO is supposed to detect by two masses moving closer together) would they not also similarly distort the wavelengths of the laser light? (The two effects would seem to cancel each other out, rendering gravitational waves indetectable.)
Have any gravitational waves been detected yet, or any simultaneous effects at two LIGO observatories which have the right characteristics?
Thanks. :^)
Question about LIGO theory (for the physicists out there)
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>cancel out
Which is why, AFAIK, the LIGOs consist of two arms at right angles to each other - if the movement cancels out in one arm then it won't in the other.
Google 'gravity wave' for more info. Not only am I not an expert I am not even a knowledgeable amateur, I haven't read the stuff that I googled yet.
A good place to start might be here:
http://www.physicscentral.com/action/action-02-8.html
Cheers,
PeterV.
a good Link for Investigation
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a good Link for Investigation this sometimes difficult Science Stuff is this
http://a9.com/?q=gravitational+waves+&submit=+GO+
[url=http://einstein.phys.uwm.edu/team_display.php?teamid=38]
http://www.guidonews.de
This is not an easy question
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This is not an easy question to answer. It turns out that the meaning of phrases such as 'the distance between the arms' and 'the wavelength of the light' depends upon the coordinate system choosen by the observer making these statements. Depending upon the choice of the coordinate system, it might be that the distance between the test masses remains fixed and the laser wavelength changes, or vice versa. However the thing that does NOT change and is independent of the choice of coordinates is the behavior of the light at the instrument's 'output' which is the antisymmetric port of the beamsplitter. This does reflect the effects of any gravitational waves.
A good place to look at the extensive literature on gravitational waves is this scientific literature catalog. (See the section at the bottom on gravitational waves.)
Two books on the subject are by Schutz and by Saulson. Note that both Schutz and Saulson are early Einstein@home members and actively accumulating credits!
An out of date but worthwhile set of slides by Peter Saulson is here .
Director, Einstein@Home
Thanks muchly for the
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Thanks muchly for the answers! Much interesting reading ahead. :^)