Gravity waves are a hypothetical "ripple in the fabric of space-time" envisioned as a consequence of Einstein's general theory of relativity. They're hypothesized to result from highly energetic events such as black hole mergers, neutrons star mergers or wobbles, etc. (though whether black holes or neutron stars actually exist is perhaps a matter for mathemagicians and/or plasma physicists / EE's to battle to the death over).
So far, it seems LIGO has failed to turn up gravity waves.
To quote from a private exchange about LIGO,
So, in short, LIGO operated continuously in parallel for an entire year during the S5 data-gathering run but turned up no gravity wave signals, examined Gamma Ray Burst GRB070201 but found no gravity wave signal, and examined the Crab Pulsar but found no gravity wave signal. So, I'm wondering, is LIGO's sole ability that of turning out null results for gravity waves? (Probably too early to tell...)I wrote:I've managed to ferret out the original LIGO press releases from Caltech and document them on Digg. The relevant entries so far are here:
(LIGO and Virgo Join Forces In Search for Gravitational Waves)
http://digg.com/space/LIGO_and_Virgo_Jo ... onal_Waves
(LIGO Sheds Light on Cosmic Event - No Gravitational Waves...)
http://digg.com/space/LIGO_Sheds_Light_ ... onal_Waves
(NSF Funnels Additional $205M Toward Advanced LIGO Project.)
http://digg.com/space/NSF_Funnels_Addit ... GO_Project
(LIGO Observations Probe the Dynamics of the Crab Pulsar; additional null result for gravity waves, 0 for 2)
http://digg.com/space/LIGO_Observations ... rab_Pulsar
Not to mention this article from Virgo, the European counterpart to LIGO:
(h, The Gravitational Voice: LIGO Bids Farewell to S5 - Now onto Enhanced LIGO!)
http://www.ego-gw.it/public/hletter/doc ... RY2008.pdf
"Unlike its four predecessor science runs, S5 had a significantly more ambitious agenda. S5 was the first long duration data-taking run where all of the interferometers were operating with astrophysically interesting sensitivities. The main goal of S5 was to collect data in triple coincidence for one year ... The end of S5 occurred only after LIGO's three interferometers, the 4 km and 2 km interferometers at the Hanford Washington Observatory and the 4 km interferometer at the Livingston Louisiana Observatory had operated synchronously (all locked simultaneously) to acquire a total of one full year of science quality data.
We are still analyzing the S5 data and while no gravitational waves have been detected, S5 has already begun to yield interesting astrophysical results. One example - an intense gamma ray burst (GRB) occurring on February 1, 2007 was detected by gamma ray satellites originating from the direction of Andromeda (M31) galaxy, possibly due of the merger of a neutron star or black hole binary system or possibly, a soft gamma repeater."
So, [if I've understood correctly,] measurements were taken in triplicate for a period of an entire year (continuously, 24/7?), but no gravitational waves turned up!
Now the NSF (National Science Foundation) has dumped $250M into the project to upgrade the technology (which should have already been capable of detecting gravity waves, but has thus far failed to do so), chasing the ghost of gravity waves. The upgrade should "increase the sensitivity of the LIGO instruments by a factor of 10, giving a one thousand-fold increase in the number of astrophysical candidates for gravitational wave signals." However, if it still continues to return "null results" for gravity waves, what does that tell us about gravity waves? How long should we continue throwing good money after what may amount to a bad idea? If gravity waves are in effect falsified, what does that do to Einstein's relativity, and to the field of cosmology?
I might ask (as I have on Digg), how can we tell the difference between an INTERESTING null result (the LIGO team has called both null results "useful" or "interesting"), a null result that tells us NOTHING, and a null result which may INVALIDATE the notion of gravitational waves altogether?
Tough questions, all... But worth the asking, if we're to be brutally and scientifically honest with ourselves.
But, since one wouldn't want to jump the shark, I guess we'll have to adopt a "wait-and-see" approach for now.