Why LIGO does not detect gravitational waves?

[Гера�им]

In the experiment LIGO not detectable gravitational waves,despite its high sensitivity is due to the fact that sources of gravitational waves are located at large distances from the Earth.The waves may change not only the sizes of pipes,but also synchronous resizes the surrounding space,therefore there are no changes in the interferometer.

[Mordred]

I have no idea on the Ligo results however BICEP2 announced it found gravity waves in the CMB.

 

http://www.scientificamerican.com/article/gravity-waves-cmb-b-mode-polarization/

 

technical papers can be found here

http://bicepkeck.org/

 

here is the arxiv paper

http://arxiv.org/abs/1403.3985

and details on the 3 year dataset

http://arxiv.org/abs/1403.4302

[imatfaal]

I have no idea on the Ligo results however BICEP2 announced it found gravity waves in the CMB.

 

http://www.scientificamerican.com/article/gravity-waves-cmb-b-mode-polarization/

 

technical papers can be found here

http://bicepkeck.org/

 

here is the arxiv paper

http://arxiv.org/abs/1403.3985

and details on the 3 year dataset

http://arxiv.org/abs/1403.4302

 

Surely both Bicep and other previous experiments (notably the spin down of binary pulsars) have confirmed the existence of gravitational waves through indirect measurements and confirmation of predictions which rely on their existence. I am not sure there has been a conclusive direct measurement of gravitational waves - there have been at least a couple of major attempts but the data noise ratio has been lower than hoped and no significant results were available.

 

edit - I am not questioning their existence - merely that we don't yet have direct measurement

[Enthalpy]

And how much embarrassing is it? Was a detectable signal reasonably expected with the achieved sensitivity, or can the experimenters still answer that predicted signals are below the noise?

[imatfaal]

And how much embarrassing is it? Was a detectable signal reasonably expected with the achieved sensitivity, or can the experimenters still answer that predicted signals are below the noise?

 

It is only embarrassing if you are naive enough to believe that experimentation is easy or that nature has some responsibility to make things simple for us. We try and we try again; it is undoubtedly disappointing - but you seem to believe that a scientific team wouldn't leap at the chance to show that GR was flawed through empirical means. Scientists may spend years trying to add evidence for established theory - but it would make their career and lead to prizes, international recognition etc if they were the team that started a revolution in cosmology and gravity.

 

The strength of the signal was, I believe, swamped the level of the noise that was encountered; ie the noise was higher than hoped, rather than the signal failing be able to measured at expected levels and with predicted noise.

[Mordred]

 

Surely both Bicep and other previous experiments (notably the spin down of binary pulsars) have confirmed the existence of gravitational waves through indirect measurements and confirmation of predictions which rely on their existence. I am not sure there has been a conclusive direct measurement of gravitational waves - there have been at least a couple of major attempts but the data noise ratio has been lower than hoped and no significant results were available.

 

edit - I am not questioning their existence - merely that we don't yet have direct measurement

I've never come across any confirmed direct measurements either.

[hoola]

I am curious as to the type of noise that swamps the experiments....what local effects could earth be having with it's constantly roiling interior, and earthquakes, whether the experiment is carried out on earth or near earth orbit...? Wouldn't the earth be a high noise area for gravitational wave detection experiments? If mars has no convection within it, and being so far out, would that be a better place to try?

[StringJunky]

I am curious as to the type of noise that swamps the experiments....what local effects could earth be having with it's constantly roiling interior, and earthquakes, whether the experiment is carried out on earth or near earth orbit...? Wouldn't the earth be a high noise area for gravitational wave detection experiments? If mars has no convection within it, and being so far out, would that be a better place to try?

 

 

Gravitational Wave Detection by Interferometry (Ground and Space)

Matthew Pitkin and Stuart Reid and Sheila Rowan and James Hough

4 Main Noise Sources

In this section we discuss the main noise sources, which limit the sensitivity of interferometric

gravitational-wave detectors. Fundamentally it should be possible to build systems using laser

interferometry to monitor strains in space, which are limited only by the Heisenberg Uncertainty

Principle; however there are other practical issues, which must be taken into account. Fluctu-

ating gravitational gradients pose one limitation to the interferometer sensitivity achievable at

low frequencies, and it is the level of noise from this source, which dictates that experiments to

look for sub-Hz gravitational-wave signals have to be carried out in space.

.

In general, for ground-based detectors the most important limitations to sensitivity result from the

effects of seismic and other ground-borne mechanical noise, thermal noise associated with the test

masses and their suspensions, and quantum noise, which appears at high frequency as shot noise

in the photocurrent from the photodiode, which detects the interference pattern and can appear

at low frequency as radiation pressure noise due to momentum transfer to the test masses from

the photons when using high laser powers. The significance of each of these sources will be briefly discussed.

http://relativity.livingreviews.org/Articles/lrr-2011-5/ (from pdf)

Edited May 20, 2014 by imatfaal
Font Correction

[Enthalpy]

 

It is only embarrassing if you are naive enough to believe that experimentation is easy or that nature has some responsibility to make things simple for us. We try and we try again; it is undoubtedly disappointing - but you seem to believe that a scientific team wouldn't leap at the chance to show that GR was flawed through empirical means. Scientists may spend years trying to add evidence for established theory - but it would make their career and lead to prizes, international recognition etc if they were the team that started a revolution in cosmology and gravity.

 

The strength of the signal was, I believe, swamped the level of the noise that was encountered; ie the noise was higher than hoped, rather than the signal failing be able to measured at expected levels and with predicted noise.

 

I did not claim nor even suggest anything. Why suppose so much? Not having the knowledge to make my own opinion about it, I try to stick to a strictly neutral approach, and I hoped my question was neutral as well.

 

I wanted to know how strong the signals were supposed to be from reasonably probable events in our vicinity, and if this strength would be detectable by the existing instruments.

[I-try]

I do not doubt for one moment the science and technology that has been expended on reoccurring gravity wave detection; also on the attempts to detect Black Holes. Both the mentioned endeavours are critically dependent on the conceptual findings of General Relativity, which in turn depends on Professor Einstein being correct regarding his interoperation of his mathematics, that correctly required that which provides reality to space is warped due to the presence of matter.

The warping of space by matter is no longer in doubt. However, it is my belief that Einstein was in error when he declared gravitation to be an illusion, and gravity only existing because matter is compelled (indicative of a force) to follow geodesic pathways. There is no description of the fundamental dynamic nature regarding how the warping occurs, except for curvature as indicated by his mathematics.

According to my work on the fundamental dynamic nature of matter, then no matter how valiantly scientists pursue the reoccurring gravity wave concept, that will fail because such waves do not travel beyond inter stellar distances and do not propagate as now expected.

I find that Einstein was correct when he stated that gravitation was not a force, nevertheless, it is a phenomenon in its own right, and becomes very evident on Earth and the Solar system.

 

The above is provided in good faith.

[Гера�им]

Thank you. Can be for detecting of gravitational waves,use power influence of gravitation in parallel with supervision of electromagnetic waves which give only indirect confirmation of existence of these waves. Besides electromagnetic waves don't interact with a dark matter which has more than visible.