When will LIGO be sensitive enough to detect gravitational wave background?

In summary, Advanced LIGO, scheduled to start in 2014, is expected to have the capability to detect gravitational waves from stellar sources. However, based on current models, it is unlikely that it will be able to detect the stochastic GW wave background and measure its temperature (which is predicted to be no more than 0.9K according to The Early Universe). The future project, Big Bang Observer, may have the potential to detect this type of background, but it is still in the early stages and not yet confirmed. The instrumentation of LIGO has been tuned to be within an order of magnitude of the predicted strain caused by polarization modes, which is about 10^-23 meters. However, this is still a very small displacement
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Advanced LIGO, scheduled to start in 2014, is believed to be able to detect gravitational waves from stellar sources. According to our best current models, does Advanced LIGO stand any chances of detecting the stochastic GW wave background? And even measure its temperature? (No more than 0.9K according to The Early Universe.)
 
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Hi,

This past Friday actually I went to a talk about LIGO and advanced LIGO. The answer given to this question was "I wouldn't bet on it".

Edit: I guess to be more specific, I think what he said was that there might be certain cases of models for which you would see something, but you probably won't for the usual models. My memory is a bit hazy though. There is also a future project called Big Bang Observer which would look for that sort of thing, although it is highly speculative right now.
 
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It's my understanding the LIGO itself is just on the cusp of possible detection, let alone aLIGO. The instrumentation has been tuned to within an order of magnitude of the predicted strain introduced by the polarization modes (about 10^-23 m or so). If you ask LIGO people what is the most likely first detection source, they'll tell you: any of them!
 
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A/4 said:
It's my understanding the LIGO itself is just on the cusp of possible detection,...

Just to be very clear, I don't think the original poster Peter was asking about LIGO's ability to detect gravitational waves from any of various sources. But your post sounds as if you think he was asking that kind of general question and as if you are responding.

Unless I'm mistaken, Peter was asking specifically about the ability to detect background GW.

That is, GW analogous to the microwave background----but from an even earlier era, nearer the start of expansion.
 
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It's my understanding the LIGO itself is just on the cusp of possible detection, let alone aLIGO. The instrumentation has been tuned to within an order of magnitude of the predicted strain introduced by the polarization modes (about 10^-23 m or so).

Measure a displacement of 10^-23 meters? Are you sure you are right? This is way shorter than the equivalent length scale of the LHC energy, which is around 10^-19 m if I'm correct.

I also want to know some technical details about LIGO. How many times does the laser beam go across the 4km vacuum tube? (I suppose they do use multiple reflection as in Michaelson-Morley?)

Thanks for answering.

P.S @Marcus Yes I'm asking about GW background, since its temperature contains information about the degree of freedom at Planck scales, which will tightly constrain, or even test, GUT and quantum gravity theories.
 
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1. When was LIGO first able to detect gravitational waves?

The Laser Interferometer Gravitational-Wave Observatory (LIGO) first detected gravitational waves in September 2015.

2. How sensitive is LIGO in detecting gravitational waves?

LIGO is currently sensitive enough to detect gravitational waves with a strain sensitivity of 10^-23, which is equivalent to detecting the change in distance of one thousandth the diameter of a proton.

3. When will LIGO be able to detect the gravitational wave background?

LIGO is expected to be sensitive enough to detect the gravitational wave background by the mid-2020s.

4. What factors affect LIGO's sensitivity in detecting gravitational waves?

The sensitivity of LIGO is affected by various factors such as the quality of the laser beams, the stability of the mirrors, seismic noise, and thermal noise.

5. How will LIGO's sensitivity be improved to detect the gravitational wave background?

LIGO's sensitivity will be improved through various upgrades, such as increasing the laser power, improving the quality of the vacuum in the detectors, and implementing new technologies to reduce noise and improve the stability of the mirrors.

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