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Is there a good chance that gravitational waves will be detected in the next years?

Theoretical estimates on the size of the effect and the sensitivity of the newest detectors should permit a forecast on this.

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Yes, most likely, unless there is something fundamentally wrong with our understanding of gravity. The most promising candidate for detection is Advanced LIGO, which is currently in the process of being designed and built. The website has some really interesting information listed, including the construction schedule (PDF), and the upgrades, such as upgrading from a 10W to a 200W laser.

According to Wikipedia, they are expecting to start operations sometime in 2014, which will be after they have completed construction and calibrated the instrument. Of particular note is that the higher power laser will make calibrating the mirrors more challenging, so right now they still have one interferometer (the shorter one) in operation and are performing a squeeze test. Once Advanced LIGO is complete, they are expecting a sensitivity increase by a factor of 10, pushing the detection rate to possibly daily.

Advanced LIGO

It may also be good to note that they are still processing the data from the old data runs (by means of Einstein@Home), so it is still possible that a detection will turn up within the data, although it will be be of a different type.

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It won't be a detection of another type, it will just be a detection in the old data. They're going to have to do huge mass sky searches with Advanced LIGO, too--don't expect a detection in advanced ligo until, at least, they've had a year to collect data and another year to analyze that data. –  Jerry Schirmer May 20 '11 at 16:09
    
@Jerry: I was under the impression that they were going to look for continuous GW sources. I live nearby the Hanford facility and have visited it a few times, and I recall the lead scientist mentioning that the analysis of the old data will look for very low frequency patterns that would not be readily apparent in a short time scale. For energetic events like neutron star mergers, though, they may detect it more quickly. The control room outputs the signal from the detector as human-audible sounds, and there is always someone monitoring it. –  voithos May 20 '11 at 16:30
    
@voithos: are you sure you're not distinguishing LIGO from LISA, rather than LIGO from advanced LIGO? The very low-frequency signals are what LISA would have (maybe hopefully still will if the ESA comes through) been looking for. The main problem with LIGO/Adv Ligo is that the actual signals are sub-noise, so they have to be matched with a template, and correlated amongst different detectors, which is expensive on the data analysis end. –  Jerry Schirmer May 20 '11 at 16:32
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@Jerry: Alright. I suppose that I was mainly thinking of Einstein@Home when I thought of data analysis. From what I understand, its search algorithm uses matched-filtering to detect continuous wave sources, not coalescing compact binaries. This PDF lists the sensitivities for various GW sources. Notably, continuous wave sources are order of magnitude lower in amplitude. –  voithos May 23 '11 at 16:53
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I neglected to bookmark it at the time (and haven't been able to find it via search since); but a few years ago someone on the E@H team linked to a poster they'd presented showing design sensitivities of current/planned future detectors and the range of expected signal strengths of known pulsars (fairly large ranges since the strength is dependent on how bumpy the surfaces are and that's currently unknown). Several pulsars were entirely within the range of Advanced Ligo's expected performance level. Only one (crab nebula?) was partially in the range of the then current hardware. –  Dan Neely Jul 30 '12 at 13:39

Yes, they expect to see a signal when advanced LIGO is up and running. Unless there is something supressing the Bh-bh, bh-ns and ns-ns merger rate, if gravitational waves exist (and the hulse-taylor binary makes this almost undeniable), then they should have a positive detection by 2020, unless there is something unknown modifying the way that gravitational waves propogate.

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