Gravity Waves

[paddoboy]

Cool down gus, cool down! And ask your Lieutenant to control his emotions, he just can't stop 'liking' your posts. You are acting like a mainstream science fanatic, science works and furthers with questioning only and only religious fanatics quell the alternative arguments, not the scientific fraternity.

And you continue to act like the fraud you are known for.

I have couple of points for your GW, these can be refuted with logic and scientific arguments, if any, without resorting to abuses.

You have nothing, including any credentials or credibility.

1. Try interacting with Prof Lewis, and ask him that spacetime itself was so confusing (and was being taught incorrectly) and now what is this "ripples in the curvature of the spacetime". You can further ask him, if it is just the mathematical geometry, then how come it takes away the Gravitational Energy?

What for? You have already chased off one professional expert with your arrogance and anti science rants.

2. Although words like Intutive and non-intutive play no role in scientific exploration,

Intuitiveness maybe foreign to yourself as a ignorant lay person [as opposed to a lay person interested in learning] but professional people within their domain of expertise, are often intuitive to the benefit of science.

but its a fact that anything which can be termed as non-intutive cannot be measured through physical disturbances? Do you think that the ripples in the "curvature of the spacetime" are intutive? Try explaining to yourslef.

Spacetime, spacetime curvature. Lense Thirring effect, gravitational radiation, are various geometrical constructs of a peer reviewed model.....Unlike the BNS.

3. GP-B, what did it measure? Geodetic? Frame Dragging? Was it conclusive in a sense that all assumptions were in line with and no other alternative explanation could have been given?

GP-B measured the Lense Thirring effect and spacetime warpage of the Earth to reasonable degrees of precision, despite your ignorant rants claiming otherwise.
https://einstein.stanford.edu/
https://einstein.stanford.edu/highlights/status1.html#PRL_paper
http://arxiv.org/abs/1105.3456
Abstract:
Gravity Probe B, launched 20 April 2004, is a space experiment testing two fundamental predictions of Einstein's theory of General Relativity (GR), the geodetic and frame-dragging effects, by means of cryogenic gyroscopes in Earth orbit. Data collection started 28 August 2004 and ended 14 August 2005. Analysis of the data from all four gyroscopes results in a geodetic drift rate of -6,601.8+/- 18.3 mas/yr and a frame-dragging drift rate of -37.2 +/- 7.2 mas/yr, to be compared with the GR predictions of -6,606.1 mas/yr and -39.2 mas/yr, respectively (`mas' is milliarc-second; 1mas = 4.848 x 10-9 rad).

To give you a clue as to what this means, the results are only curtailed by the accuracy of our equipment and technology.
Without doubt, those accurate figures will be improved on in time.
Gravity Probe B, launched 20 April 2004, is a space experiment testing two fundamental predictions of Einstein's theory of General Relativity (GR), the geodetic and frame-dragging effects, by means of cryogenic gyroscopes in Earth orbit. Data collection started 28 August 2004 and ended 14 August 2005. Analysis of the data from all four gyroscopes results in a geodetic drift rate of -6,601.8+/- 18.3 mas/yr and a frame-dragging drift rate of -37.2 +/- 7.2 mas/yr, to be compared with the GR predictions of -6,606.1 mas/yr and -39.2 mas/yr, respectively (`mas' is milliarc-second; 1mas = 4.848 x 10-9 rad).

4. I do agree on H-T paper, the nobel they got, but measuring something which requires sensitivity of the order of 1:10^20+, based on certain observations as taken of a star system which is few thousand light years away...cannot be a great confidence boosting stuff.

So says our infallible god, who lacks credibility, lacks credentials, and lacks any respect from anyone of any note....

5. And I like the question as asked by Danshawen, Ripple means contraction/expansion with respect to what and the fulcrum?

I would suggest then, that if you have any idea or any evidence supporting what you are trying to say, you, and Danshawen, would not be here.
But you are...That my dear friend says it all.

Are we not moving towards giving certain materialistic property to spacetime ?

Spacetime is our model against which GR operates.
http://einstein.stanford.edu/content/relativity/q411.html
In 1906, soon after Albert Einstein announced his special theory of relativity, his former college teacher in mathematics, Hermann Minkowski, developed a new scheme for thinking about space and time that emphasized its geometric qualities. In his famous quotation delivered at a public lecture on relativity, he announced that,

"The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are radical. henceforth, space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality."

This new reality was that space and time, as physical constructs, have to be combined into a new mathematical/physical entity called 'space-time', because the equations of relativity show that both the space and time coordinates of any event must get mixed together by the mathematics, in order to accurately describe what we see. Because space consists of 3 dimensions, and time is 1-dimensional, space-time must, therefore, be a 4-dimensional object. It is believed to be a 'continuum' because so far as we know, there are no missing points in space or instants in time, and both can be subdivided without any apparent limit in size or duration. So, physicists now routinely consider our world to be embedded in this 4-dimensional Space-Time continuum, and all events, places, moments in history, actions and so on are described in terms of their location in Space-Time.

Space-time does not evolve, it simply exists. When we examine a particular object from the stand point of its space-time representation, every particle is located along its world-line. This is a spaghetti-like line that stretches from the past to the future showing the spatial location of the particle at every instant in time. This world-line exists as a complete object which may be sliced here and there so that you can see where the particle is located in space at a particular instant. Once you determine the complete world line of a particle from the forces acting upon it, you have 'solved' for its complete history. This world-line does not change with time, but simply exists as a timeless object. Similarly, in general relativity, when you solve equations for the shape of space-time, this shape does not change in time, but exists as a complete timeless object. You can slice it here and there to examine what the geometry of space looks like at a particular instant. Examining consecutive slices in time will let you see whether, for example, the universe is expanding or not.
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

Perhaps my dear god that may give you a clue as to your crazy anti science rants.
Of course if you chose to refute anything, please supply a reputable link and reveal your credentials.
Neither of course will happen. You'll continue to carry on regardless in your usual bollywood arrogant fraudster like ways. This forum is your only outlet. Anywhere else you would be banned, if you havn't already been banned for your nonsensical take on science.

 

[paddoboy]

:atomic gravitational wave interferometric sensor:

http://arxiv.org/abs/0806.2125

We propose two distinct atom interferometer gravitational wave detectors, one terrestrial and another satellite-based, utilizing the core technology of the Stanford 10 m atom interferometer presently under construction. Each configuration compares two widely separated atom interferometers run using common lasers. The signal scales with the distance between the interferometers, which can be large since only the light travels over this distance, not the atoms. The terrestrial experiment with baseline ~1 km can operate with strain sensitivity ~10^(-19) / Hz^(1/2) in the 1 Hz - 10 Hz band, inaccessible to LIGO, and can detect gravitational waves from solar mass binaries out to megaparsec distances. The satellite experiment with baseline ~1000 km can probe the same frequency spectrum as LISA with comparable strain sensitivity ~10^(-20) / Hz^(1/2). The use of ballistic atoms (instead of mirrors) as inertial test masses improves systematics coming from vibrations, acceleration noise, and significantly reduces spacecraft control requirements. We analyze the backgrounds in this configuration and discuss methods for controlling them to the required levels.


VIII. CONCLUSION
A. Comparison with Previous Work Previous studies on the role of atom interferometers in gravitational wave detection concluded that they would be of limited use in probing the gravitational wave spectrum. Our proposal differs significantly from these efforts owing to the central role played by light pulse interferometry in our setup. The work of [15], [24] and [25] used material mirrors like diffraction gratings to execute the interferometer. The gravitational wave signal in the configurations considered in these papers is ∼ khd where k is the momentum of the atom, h the amplitude of the gravitational wave and d the distance between the mirrors. It is experimentally difficult to make the distance between these mirrors bigger than ∼ 1 m. Even if the distance between the mirrors were to be increased, the experiment would still be difficult since the separation between the two arms of the atom’s wave function must also be equally scaled. These considerations forced the authors to conclude that an unrealistic atom flux would be needed to see a gravitational wave. The use of material mirrors suffers from the additional drawback that the mirrors would be subject to vibration noise. The mirrors would have to be placed on vibration isolation stacks so this interferometer would be subject to the same limitations as light based interferometers like LIGO. The work of [26] and [27] described atom interferometers which used light pulse interferometry. However, these authors did not consider the effect of the gravitational wave on the light pulses used to execute the interferometry. Without this effect, the phase shift in the interferometer is ∼ khd where d is the separation between the two arms of the interferometer (see discussion in Section III B). Since the separation between the two arms of the interferometer cannot be easily scaled, these authors were also forced to consider unrealistic atom fluxes. Moreover, these papers did not discuss strategies to handle crucial backgrounds to gravitational wave detection like vibration and laser phase noise. In this paper, we point out that the effect of the gravitational wave on the light pulses used to execute the interferometer is crucial and can be easily scaled to increase the signal. When the interferometer is operated by a laser at a distance L, a gravitational wave of amplitude h causes a phase shift ∼ khL. This signal increases as long as L is smaller than the wavelength of the gravitational wave. Unlike the separation between the two arms of the atom’s wave function, the distance between the atom and the laser can be easily scaled. With L ∼ 10 km, the signal in this interferometer is 104 larger than the signal in the configurations previously considered. In addition to boosting the signal, the configuration considered in this paper offers an effective way to deal with vibration and laser phase noise. By using the same laser to run two widely separated interferometers and measuring the differential phase shift between the two interferometers, this setup drastically suppresses the effects of vibrations and laser phase noise. Our setup thus achieves a large, scaleable enhancement in the signal while simultaneously suppressing backgrounds thereby making it possible to search for gravitational waves with current technology. The SAGAS [74] project that uses atom interferometry and ion clock techniques to explore gravity in the outer solar system was proposed. SAGAS will improve current bounds on stochastic gravitational waves in the frequency band 10−5 Hz − 10−3 Hz but is not expected to be sensitive to known sources of gravitational radiation. In contrast, our proposal will search for gravitational waves in the 10−3 Hz − 10 Hz band at sensitivities that can detect gravitational waves from expected sources.

 

[The God]

Paddoboy,

You have not provided any argument against any of the points raised. You just copied something from somewhere and usual abusive barkings. Your Post #62 is shear non-sense without any intelligent(?) comment from your side, about the post. Just positing some copied stuff is no argument, rather it shows your inability to form any intelligent opinion.

 

[danshawen]

The nested quote either is not mine or is heavily edited.

I consider a fair number of folks here " friends", including you, paddoboy, and a few others who would no doubt be abashed at having earned such respect, but I don't believe I ever referred to this other individual as a 'friend'. Please refrain from the malodorous practice of attributing quotations I never composed, or you will learn what "unfriend" means.

Despite how it may appear to you, I don't hand out "likes" like a broken candy machine, nor does it mean that because you or someone else may receive them, I consider a poster of something I like a friend. They are a sort of intellectual currency here, that is all.

 

[Maxila]

Lots of bullshit in the first paragraph. These physicists must have forgot to review all the evidence before they started their search.

I agree, I thought the title and the first sentence were a bit misleading that's why I quoted and underlined the latter part of the article.

 

[paddoboy]

Paddoboy,

You have not provided any argument against any of the points raised. You just copied something from somewhere and usual abusive barkings. Your Post #62 is shear non-sense without any intelligent(?) comment from your side, about the post. Just positing some copied stuff is no argument, rather it shows your inability to form any intelligent opinion.

the god:
You have not provided any evidence or reputable link to support anything you claim, and your credentials to question anything of mainstream is zilch, nada, nil.
Your continued ignoring and refusal to these reasonable requests of supplying reputable links and your credentials, places you in pseudoscience territory and a total crank lacking all credibility.


PS: My reputable copy's and pastes will continue, just as my Tutorial remains correct and unchanged.

 

[brucep]

I agree, I thought the title and the first sentence were a bit misleading that's why I quoted and underlined the latter part of the article.

It was pretty strange not knowing the experimental literature on the subject. I'm guessing they're not up to date on the experimental literature. It might be interesting to find out how they meant to get results and when they didn't why it means they don't exist?

 

[brucep]

:atomic gravitational wave interferometric sensor:

http://arxiv.org/abs/0806.2125

We propose two distinct atom interferometer gravitational wave detectors, one terrestrial and another satellite-based, utilizing the core technology of the Stanford 10 m atom interferometer presently under construction. Each configuration compares two widely separated atom interferometers run using common lasers. The signal scales with the distance between the interferometers, which can be large since only the light travels over this distance, not the atoms. The terrestrial experiment with baseline ~1 km can operate with strain sensitivity ~10^(-19) / Hz^(1/2) in the 1 Hz - 10 Hz band, inaccessible to LIGO, and can detect gravitational waves from solar mass binaries out to megaparsec distances. The satellite experiment with baseline ~1000 km can probe the same frequency spectrum as LISA with comparable strain sensitivity ~10^(-20) / Hz^(1/2). The use of ballistic atoms (instead of mirrors) as inertial test masses improves systematics coming from vibrations, acceleration noise, and significantly reduces spacecraft control requirements. We analyze the backgrounds in this configuration and discuss methods for controlling them to the required levels.


VIII. CONCLUSION
A. Comparison with Previous Work Previous studies on the role of atom interferometers in gravitational wave detection concluded that they would be of limited use in probing the gravitational wave spectrum. Our proposal differs significantly from these efforts owing to the central role played by light pulse interferometry in our setup. The work of [15], [24] and [25] used material mirrors like diffraction gratings to execute the interferometer. The gravitational wave signal in the configurations considered in these papers is ∼ khd where k is the momentum of the atom, h the amplitude of the gravitational wave and d the distance between the mirrors. It is experimentally difficult to make the distance between these mirrors bigger than ∼ 1 m. Even if the distance between the mirrors were to be increased, the experiment would still be difficult since the separation between the two arms of the atom’s wave function must also be equally scaled. These considerations forced the authors to conclude that an unrealistic atom flux would be needed to see a gravitational wave. The use of material mirrors suffers from the additional drawback that the mirrors would be subject to vibration noise. The mirrors would have to be placed on vibration isolation stacks so this interferometer would be subject to the same limitations as light based interferometers like LIGO. The work of [26] and [27] described atom interferometers which used light pulse interferometry. However, these authors did not consider the effect of the gravitational wave on the light pulses used to execute the interferometry. Without this effect, the phase shift in the interferometer is ∼ khd where d is the separation between the two arms of the interferometer (see discussion in Section III B). Since the separation between the two arms of the interferometer cannot be easily scaled, these authors were also forced to consider unrealistic atom fluxes. Moreover, these papers did not discuss strategies to handle crucial backgrounds to gravitational wave detection like vibration and laser phase noise. In this paper, we point out that the effect of the gravitational wave on the light pulses used to execute the interferometer is crucial and can be easily scaled to increase the signal. When the interferometer is operated by a laser at a distance L, a gravitational wave of amplitude h causes a phase shift ∼ khL. This signal increases as long as L is smaller than the wavelength of the gravitational wave. Unlike the separation between the two arms of the atom’s wave function, the distance between the atom and the laser can be easily scaled. With L ∼ 10 km, the signal in this interferometer is 104 larger than the signal in the configurations previously considered. In addition to boosting the signal, the configuration considered in this paper offers an effective way to deal with vibration and laser phase noise. By using the same laser to run two widely separated interferometers and measuring the differential phase shift between the two interferometers, this setup drastically suppresses the effects of vibrations and laser phase noise. Our setup thus achieves a large, scaleable enhancement in the signal while simultaneously suppressing backgrounds thereby making it possible to search for gravitational waves with current technology. The SAGAS [74] project that uses atom interferometry and ion clock techniques to explore gravity in the outer solar system was proposed. SAGAS will improve current bounds on stochastic gravitational waves in the frequency band 10−5 Hz − 10−3 Hz but is not expected to be sensitive to known sources of gravitational radiation. In contrast, our proposal will search for gravitational waves in the 10−3 Hz − 10 Hz band at sensitivities that can detect gravitational waves from expected sources.

Thanks for posting the paper.

 

[paddoboy]

The nested quote either is not mine or is heavily edited.

? Are you referring to post 55? If so I apologise, and the phrase with the IMNSHO in, is my quote of what our resident ego inflated clown used. In short, I stuffed up with that post but too late to rectify now....
What should have been......
danshawen said: ↑
Correct, as usual.
I said in reply:
My friend the god and his "IMNSHO" would strike you down for such a blasphemous statement.
And on that point he would be right.
danshawen said:
Paddoboy's example of the Hulse-Taylor binary gravity wave detection is the best example so far of gravity wave detection by means of comparing orbital decay to that predicted by GR. The periastron of the pair is analogous to the GR solution to the perihelion of Mercury. As the pair approach each other, significant gravity wave energy is released causing the orbits to decay, and agreement with the prediction of GR has been very close over the span of several decades of observation.
I said:
Being around 23,000 L/Years distant and your mention of time dilation, I'm not sure I understand properly, suffice to say once again, that all frames of references are as valid and as real as each other.

 

[brucep]

? Are you referring to post 55? If so I apologise, and the phrase with the IMNSHO in, is my quote of what our resident ego inflated clown used. In short, I stuffed up with that post but too late to rectify now....
What should have been......
danshawen said: ↑
Correct, as usual.
I said in reply:
My friend the god and his "IMNSHO" would strike you down for such a blasphemous statement.
And on that point he would be right.
danshawen said:
Paddoboy's example of the Hulse-Taylor binary gravity wave detection is the best example so far of gravity wave detection by means of comparing orbital decay to that predicted by GR. The periastron of the pair is analogous to the GR solution to the perihelion of Mercury. As the pair approach each other, significant gravity wave energy is released causing the orbits to decay, and agreement with the prediction of GR has been very close over the span of several decades of observation.
I said:
Being around 23,000 L/Years distant and your mention of time dilation, I'm not sure I understand properly, suffice to say once again, that all frames of references are as valid and as real as each other.

Just to clear up the danshawen nonsense. Eienstein orbits naturally precess. So the test associated with Einstein orbits is to measure the natural precession of orbits and compare with the theoretical prediction. The gravitational wave experiment measures the change in orbital circumference and energy due to the gravitational radiation. I'm guessing the change in circumference of Mercury orbit due to gravitational radiation is an infinitesimal. That' why we needed a better relativistic setting, the binary pulsars, to indirectly detect the changes, per lifetime, orbit, second, whatever we want to know.

Derive the natural precession rate of Einstein orbits. All Einstein orbits naturally precess.
Start with the Schwarzschild metric, in geometric units, setting theta at 0.
dTau^2 = (1-2M/r)dt^2 - dr^2/(1-2M/r) - r^2(dphi)^2
Substituting constants of geodesic motion E/m and L/m for dt and dphi
dt = [(E/m)/(1-2M/r)]dTau
dphi = [(L/m)/r^2]dTau
The solution relates squared values for radial motion (dr/dTau)^2, energy per unit mass
(E/m)^2, and the effective potential per unit mass (V/m)^2 = (1-2M/r)(1+[(L/m)^2/r^2]).
(dr/dTau)^2 = +/- (E/m)^2 - (1-2M/r)(1+[(L/m)^2/r^2])
Taking some license for the weak field and multiplying through by 1/2 after multiplying out the squared effective potential
1/2(dr/dTau)^2 = 1/2(E/m)^2 - [1/2 - M/r + (L/m)^2/2r^2 - M(L/m)^2/r^3]
setting (V/m)^2 = U/m
U/m = 1/2 - M/r + (L/m)^2/2r^2 - M(L/m)^2/r^3
1st derivative
d(U/m)/dr = M/r^2 - (L/m)^2/r^3 + 3M(L/m)^2/r^4
2nd derivative d'2(U/m)/dr'2 = rate of radial oscillation = w^2_r
w^2_r = M(r-6M)/r^3(r-3M)
Without writing down details the rate of angular velocity becomes
w^2_phi ~ (dphi/dTau)^2 = M/r^2(r-3M)
The difference.
w^2_phi - w^2_r = 6M^2/r^3(r-3M)
We can find a factor * M/r^3 which closely approximates 6M^2/r^3(r-3M)
That factor is 6M/r
(6M/r)(M/r^3) = 6M^2/r^4
The last step is further weak
field approximation
(6M/r)^1/2 ~ 1/2(6M/r) = 3M/r
So a very close approximation for the rate of orbital precession, in the weak field is 3M/r. You can plug in numbers and get an answer that matches observation.
3M_Sun = 4431mr_mean Mercury = 5.8x10^10 meters415.1539069 times Mercury orbits the Sun in 100 Earth years360 degrees per year3600 arcseconds per degreeetc...
It would be interesting to find out if 3M/r works for the binary pulsars natural precession. Probably not without some relativistic adjustment.

 

[quantum_wave]

...
LISA is really just another one-observer gravity wave detector in free fall around the Sun, just like Earthbound variations of the same instruments, ...

I thought that is was to be placed in orbit around a Lagrange point between the Earth, moon, and sun, where the gravitational force from all three equals out, and is to stay there for six or eight months. Also, the two small gold cubes are not fixed in the same frame, they are carefully placed and monitored, but are able to move independently relative to each other if a gravitational wave passes by, which is what sets off the interferometer. I don't think you should call it a single frame experiment, as I understand it.

 

[danshawen]

I thought that is was to be placed in orbit around a Lagrange point between the Earth, moon, and sun, where the gravitational force from all three equals out, and is to stay there for six or eight months. Also, the two small gold cubes are not fixed in the same frame, they are carefully placed and monitored, but are able to move independently relative to each other if a gravitational wave passes by, which is what sets off the interferometer. I don't think you should call it a single frame experiment, as I understand it.

OK, it's time to put the final nail in the lid for local detection of gravity waves.

The binary system is generating gravitational radiation that is the approximate power output of our own Sun. It is doing so at a distance of about 23,000 light years from us, which places it in the Milky Way orbiting the center at close to the same rate of galactic rotation as the Sun and our solar system.

If LISA orbits at the Earth Moon Sun Lagrange point, what would be your estimate of the DIFFERENCE in luminous intensity of a star that is the same size and luminous intensity as our Sun at the same distance from us? Would there be a measurable difference in luminosity IN TERMS OF THE SAME INVERSE SQUARE RELATION WE USE FOR LIGHT? If there were essentially no difference in luminosity for photons, then GUESS WHAT? There will be no difference in luminosity FOR GRAVITY WAVES either. But for a gravity wave, the only means of detecting them is by comparison with spatial and temporal distortions that are very far removed from this locality. If you do not separate detectors by a much greater amount, time may distort, and space may distort, but as relativity commands, NO EXPERIMENT you can perform locally will be able to detect such distortions. A gravity wave propagating through a bank of 100 meter interferometers within light minutes of each other are simply too close to measure any such variations. Micahelson-Moreley failed for exactly the same reason these will.

Only an experiment similar to Hulse-Taylor can ever succeed in detecting gravitational radiation, even in small measure, because the time reference is the pulsar, which is local to the gravity wave point of origin. The reference is far enough from us to allow us to compare Doppler shifts using our own local, non-Doppler shifted time to interpret how the gravitational decay is proceeding.

Has anyone looked for FM Doppler shift in radio spectra of stars in the vicinity of this binary system correlated with their corrected periods of rotation? Passing gravity waves also would do that, and we are plenty far enough away from them to determine if this happens. There's your secondary gravity wave detector / confirmation, if there will ever be one.

 

[brucep]

I thought that is was to be placed in orbit around a Lagrange point between the Earth, moon, and sun, where the gravitational force from all three equals out, and is to stay there for six or eight months. Also, the two small gold cubes are not fixed in the same frame, they are carefully placed and monitored, but are able to move independently relative to each other if a gravitational wave passes by, which is what sets off the interferometer. I don't think you should call it a single frame experiment, as I understand it.

Both the LISA and eLISA experiments would be conducted in a single local Laboratory inertial frame of reference. The experimental device defines the boundary of the experiments local Laboratory frame. Just like a really big CERN since the distance of the eLISA arms would be 1E6 km and the distance of the LISA arms would be 5E6 km.

 

[danshawen]

Both the LISA and eLISA experiments would be conducted in a single local Laboratory inertial frame of reference. The experimental device defines the boundary of the experiments local Laboratory frame. Just like a really big CERN since the distance of the eLISA arms would be 1E6 km and the distance of the LISA arms would be 5E6 km.

If the gravity distortions mean that time and space change by the same amount and in the same direction, and if there is no local means for recording the effects of the passage in a manner that allows comparison of time/space before, during, and after the gravity wave passes, there is simply no way that can work.



The Michaelson Morley experiment was designed to look for an "aether wind" in the medium in which light propagates. It turned out that "aether" had NO INERTIA of any kind, and that a new kind of thinking (relativity) was needed in order to solve the problem. E delivered.

In free fall, as we are with respect to the binary system emitting gravity waves, the only means of measuring a difference in spacetime between there and here is simply to measure a difference in spacetime between there and here. The spectra of stars are already Doppler shifted. This is the only clock (other than the Hulse-Taylor pulsar) distant enough to use for the purpose of comparing the passage of time near the source of a gravity wave to the one passing our location.

All of our instruments are made of the bound energy of atoms, which may shrink and stretch and experience time dilation and contraction as the gravity wave passes, but it will leave no record of having passed that is measurable by instruments affected by it. The unbound energy of photons are also curved by gravitation, and their frequency is affected by variations in time dilation produced by gravity waves as well, but this is something you need to look for in ways not affected by the passage of a local gravity wave. This is the only practical means for detecting a gravity wave.

LIGO and LISA are both just local "aether wind" detectors, as you would expect from their designs. There is no aether wind, since 1905.

 

[quantum_wave]

Both the LISA and eLISA experiments would be conducted in a single local Laboratory inertial frame of reference.
...

If there are two independently suspended objects (the gold cubes) within the local Lab, and there is motion of one relative to the other, doesn't that qualify the two cubes as two inertial reference frames?

 

[danshawen]

If there are two independently suspended objects (the gold cubes) within the local Lab, and there is motion of one relative to the other, doesn't that qualify the two cubes as two inertial reference frames?

Yes they are (in different frames in terms of the passage of local time, length contraction, and the rest). You will be able to verify this, just as it is possible to measure temporal differences between GPS satellites and the ground, the temporal differences between orbits (like the Shapiro delay), different altitudes & etc.

None (or more to the point, ALL) of these effects are equivalent to those of a passing gravity wave, in which time dilation temporarily changes everywhere and then goes back to "normal" (whatever that is) over an expanding circular or essentially a planar wavefront in a VERY large region of space. All of these frames are in free fall with respect to the binaries. There is nothing that is special about their frames of reference either, but to measure differences between theirs and ours, you still must measure differences, not do an endless rehash of Michaelson-Morley locally.

Finding an appropriate means for measuring gravity waves using only Doppler shifts may not even be possible (the number of confounding relative motions will be VERY large compared to the subtle effect you are looking for), but it is the only practical means of detecting a passing gravity wave.

 

[Q-reeus]

...None of these effects are equivalent to those of a passing gravity wave, in which time dilation temporarily changes everywhere and then goes back to "normal" (whatever that is) over an expanding circular or essentially a planar wavefront in a VERY large region of space...

That erroneous, oft repeated notion of yours was supposed to have been laid to rest in another thread re LIGO. So, again, the article I cited there:
https://www.aapt.org/doorway/tgrutalks/Saulson/SaulsonTalk-Teaching gravitational waves.pdf
Note carefully - in GR's GW picture there is precisely zero time dilation occurring - only spatial purely transverse shear deformations.
It's so much like Groundhog Day at SF.

 

[danshawen]

So, if there were gravity waves in the vicinity of the binary system, then we should be able to see that in the form of SHEER TRANSVERSE DEFORMATIONS OF THE SPACETIME OF NEIGHBORING STARS, right? But how would we know that, even if we saw a candidate event in that region? Same way that we would know what caused such an event here; you wouldn't.

How anyone imagines that there will be sheer transverse deformation due to the passage of a GW without a concomitant time dilation effect in the same region reveals someone who doesn't understand the first thing about relativity. Not even wrong.

Detecting gravity waves with an interferometer of any practical size is breaking relativity's law in terms of performing a local experiment which demonstrates motion of the medium through which light waves travel. Anyone who has other ideas about this is the one who needs to justify some very expensive experiments with null results which have already been done and noted and were in fact the motivation for the creation of relativity theory in the first place.

Interferometry is used all the time in astronomy to discern multiple images produced by gravitational lensing. This is so routine, in fact, that by now someone should have noticed if any such lensing activity is moving, the rate at which it is moving, and whether there are any distortions of this kind that are affecting transverse deformations of spacetime of nearby stars. But how could you even tell if it was due to GW or lensing?

All of the above discussion assumes only that the medium through which light propagates is the same medium through which GWs propagate, of course.

 

[danshawen]

From Saulson's own slideshow:

"It is true, absolutely, that the instantaneous response of the light in an interferometer to a gravitational wave is in fact null."

This is all I am saying. This isn't taken out of context. It is what it is. The rest is commentary.

 

[brucep]

If there are two independently suspended objects (the gold cubes) within the local Lab, and there is motion of one relative to the other, doesn't that qualify the two cubes as two inertial reference frames?

The experiment is conducted in the local proper laboratory frame because the geometry of the experiment fits the local proper laboratory frame in our solar system. This means the spacetime curvature over this geometry is an infinitesimal and for this experiment the effects of gravity can be ignored. IE the spacetime in the lab frame where the xperiment is conducted is flat. Same as the particle experiments at CERN. Not the same for the GPS where infinitesimal delta proper tick rates have a negative effect on operations.