Does gravitational waves decays?

Dear Jay Vora ,

Any wave, as far as seen, if propagating through a dissipative material medium, must decay.

If the medium remains the vacuum, the waves and instabilities would remain propagatory without any significant amplitude decay forever due to the fact the vacuum energy expectation value remains a non-zero finite due to quantum fluctuations.

With best wishes.

The complication with gravitational waves is that the things are inherently nonlinear.

Consider a piston accelerating back and forth in a chamber. The piston feels geeforces due to acceleration pulling on it one, way, and then the other way, repeatedly. It seems to the piston that there is an alternating gravitational field tugging it one way and then the other, which it can relate to the outside universe's surrounding mass, relatively accelerating one way and then the other.

According to the general principle of relativity, the piston's viewpoint is legitimate, and the principle of mutuality then also requires the oscillation of the piston's mass to produce alternating "push" and "pull" fields in the vicinity. Forced relative acceleration of a mass ought to generate a gravitational signal.

We then expect the influence of these fields to propagate away from the piston, at the speed of light. We then have gravitational waves being created in front of and behind the piston, with the wavefronts at right angles to the piston's motion axis.

The problem is that if the fast and slow wavefronts travel at the speed of light, but the presence of the wavefronts alters the speed of light, then we can calculate a sort of extinction distance at which the faster half of the wavecycle actually catches up with the earlier slower half. Beyond this distance we get nonsensical results in which the faster half would overtake the slower half.

So this suggests self-extinction.

A further complication is that if part of the cycle represents an increasing velocity of light, then the later part might be expected to be catching up with the earlier part, making the wavefront more abrupt. Even before we get to the collision/extinction distance, we have the problem that a compacting wavefront shape implies increasing energy: distortion of a sinewave into a sawtooth involves adding higher-energy higher-frequency (shorter-wavelength) components.

Since it seems silly for a propagating gravity-wave to be increasing in energy, we seem to have to either have it reducing in amplitude (somehow) to compensate, or we need some mechanism to resist compaction to a sawtooth (perhaps spacetime's dislike of being bent). In an acoustic metric description, the signal propagation speed can be dictated not just by the nominal speed at the pointlike locations it passes through, but also by a kind of "smeared" version of the nearby speeds. Smearing means that the initial wavefront of a fast cycle can propagate though a region faster than the region's nominal speed of the wave wasn't there: the approaching wave preconditions the region directly ahead. Under QM we can say that the wavefront experiences a lightspeed barrier, but that it influences the region ahead of the barrier by information quantum-tunneling forwards (Hawking radiation).

Snag is, if these effects are constantly blurring the gravity-wave, then it's not obvious that they shouldn't be robbing it of energy, and making the wave straighten out and convert to extra distance (like a ripple in a carpet disappearing and resulting in more carpet length).

If this happens, there's a form of energy-conservation in that if the waves are being emitted by double-star, and start straightening themselves out as they leave the star system, the straightening-out results in a tiny increase in distance all around the star, which makes its gravity-well appear deeper. To an outside observer, the energy in the gravity-waves is being drained, but is then appearing as gravitational energy (or as some other sort of energy associated with extra distance) around the double-stars.

Trouble is, I'm not sure that the mainstream have ever tried modelling any of these possible nonlinear effects. It would be slightly embarrassing if our hardware successfully "proved" the predictions of an idealised model that then turned out to be wrong.

Gravitational waves decay like EM, so the power falls as r^-2 in free space, but LIGO measures only the strain which is like just one part of the EM field so that falls as r^-1. That

The waves couple very poorly to matter so it has no dissipative effect and is essentially transparent to them but they are affected by gravity in the same way as light so subject to gravitational bending and the Shapiro delay for example. Weber Bars were constructed in such a way that they resonated at a specific frequency but could only extract any energy over a very narrow frequency.

Keplerian orbits can be assumed when the bodies are far apart and the waves frequency from that period tells us basic properties like the chirp mass and luminosity distance. Non-linear effects are very important in the strong field region which occurs close to the final merger and decades of work on supercomputers was required to create the templates predicted by GR which can be used for comparisons and extraction of additional parameters like mass ratio and spins.

You can discount any criticism that LIGO didn't detect waves, they published the exact location and range of GW170817 some 12 hours before it was found and that was what allowed the successful highly targeted search by SWOPE. The range given meant they could examine just a handful of galaxies instead of thousands in the area of the sky and subsequent optical measurements confirmed their figure was accurate to within 5%.

There are a lot of people out there with "theories" that said waves couldn't exist who now have trouble dealing with reality.

TDM: ... or following to self-injection by the programmers as was reported ...

Think before posting Thierry, they reported it 12 hours before anybody ever saw it. You seem to be another person who believes in time machines, if you have one, can you tell me who will be the winner of next year's Superbowl please, I feel like placing a bet.

Of course it is proof when they provided all the details that allowed others to subsequently find the object.

If they remained as strong as they are at the time the are created, we would see the effects on all planetary bodies. Like bobbers on a lake. Therefore as they dissipate, also shall the decay.

Dear All,

George>: Gravitational waves decay like EM, so the power falls as r^-2 in free space, but LIGO measures only the strain which is like just one part of the EM field so that falls as r^-1.

The strain is the length change per length. The gravitational wave is moving outward in all directions. Thus every point of a sphere around the centre of gravity of the source at equal distance can be called one time moment of the wave. The movement of the wave is perpendicular to that sphere surface and the strain should be measured in the surface of that sphere. That sphere can be described with an equator in the plane of rotation and poles at the rotation axis. The wave is a quadrupole wave. That means with one full rotation of the source there are two maxima and two minima. We can thus assume that along the equator there are tow maxima at 180° and two minima again at 180° but shifted by 90°. In between these maxima and minima there are again at 90° separation four position with no strain. These positions are the zero crossings.

When areas with a positive strain are placed next to each other, followed by areas of negative strain, then if the number of areas are the same then measured in the direction of the strain the same number of areas with positive train take more length than the areas with negative strain. As a result the positions of zero strain are not exact at 90° angle along the equator. They are moved towards the positions with maximum negative strain or, as I called it, the minima.

The rotation of the source means that the configuration as described will rotate with the same angular velocity as the source had when the effect was created at the source. That is no movement of space but it is because the outward wave has a phase difference measured along the equatorial direction. The maximal deviation of the zero crossing from the 90° position, as mentioned above, is however the change of the coordinates of space. We can't have a strain if we can't stretch space. If space is stretched different then the place with maximum displacement has to change.

The strain will fall as r^-1 as is mentioned by George Dishman. The length measured along the equator of the wave sphere will grow with r. The result is that the displacement, we talked about, is constant. I have calculated that this displacement is in the order of 0.6mm. If the mirrors at LIGO would follow the strain, that is, if they would change their relative distance by following the change in space length, then they should also follow the displacement I mentioned. The effect that looks like the result of the strain is measured in LIGO. The displacement, if measured in LIGO, would change the arm length of one arm with respect to the perpendicular arm over this 0.6mm. This is many times the wavelength of the used laser light. So, if this displacement would have happened then the extreme strong laser would have burned out the light sensor.

My conclusion is that space didn't stretch or contract and thus gravitational waves are no metric event.

I look forward to comments and or corrections.

Regards,

Paul Gradenwitz

Dear Paul,

PG: My conclusion is that space didn't stretch or contract and thus gravitational waves are no metric event.

The metric is defined in terms of derivatives so is local at a point and remains a valid description over the scale of the planet.

Dear Thierry,

TDM: No George, without an object in the direction, it is no proof ....

The SWOPE discovery image of the object is here:

Here are Hubble's photographs of the object on three separate days about a week later when it was clearly fading.

Dear George Dishman,

George>: The metric is defined in terms of derivatives so is local at a point and remains a valid description over the scale of the planet.

The metric is defined in derivatives. But when you can't integrate them then they make no sense. The wavelength of the GW is in the 6000km range, the earth is double that site so no way that earth can follow the sheer of that wave. The mirrors only can follow the differential expansion if they follow the large scale expansion.

The metric describes the GW in terms of space geometric changes. The real GW is a complete different process that happens to follow in effect what GRT describes to the differential level.

You can describe a wave made of a sheet. The whole amplitude is there. Two ants walking on that sheet and touching with their antlers measure their differential hight. But that only makes sense if they together ride up and down the wave. So, only when the mirrors move the full amplitude in nearly perfect parallel then also the differential can have an effect on the mirrors. If not, then space didn't move and GRT needs rethinking.

Regards,

Paul Gradenwitz

Dear Paul,

The diameter of the Earth is ~12700 km or of the order of 10⁶m and the strain is less than 10^-21 which means the shear is of the order of 10^-15m over half a wavelength. The size of an atom is around 10^-10m. Squeezing the width of the planet by 10^-5 of the size of an atom doesn't cause a problem as far as I can see, especially since any motion of the atoms is resisted by their inertia.

Relative to the beam tubes, the mirrors only move 10^-21 times 4km or less than 10^-17m.

Dear George Dishman,

How do you calculate the sheer? Maybe what I call sheer is not what you call sheer. The coordinates of space, as you showed them in your vimeo film are, without wave, equidistant spaced in your band in the equatorial region. With wave they deviate maximal by the sheer amount. In our case that is as I calculated about 0.6mm. In one instant in time there are shells of spheres inside each other with rotated versions of the deviation. Each time the deviation in one radial coordinate line is measured from the undisturbed line. So when the wave moves outward then the coordinate position of space moves sidewards with the absolute amplitude. A different coordinate, at some distance along the sphere, also moves sidewards withe the same amplitude but a small phase shift that results in a relative distance change of the small 5x10^-22 but along the line inward towards the source the deviation follows the full amplitude. The wavelength of 6000 km is less than one twentieth (I made an error of a factor 10) of the 127000 km. The sheer between points separated by 6000km inward is the value from maximal one direction to maximal the other direction and that would be about 1.2mm.

You take the strain that is defined perpendicular to the wave moving direction and apply it in the direction of movement. The wavelength can't be multiplied by the strain to get the sheer.

Regards,

Paul Gradenwitz

The shear doesn't accumulate though space so take a line through the centre of the Earth pointing at the source and the atoms along that line are unmoving. The diameter increases or decreases symmetrically about that line and if you then think of the planet as made of thin disks perpendicular to that line, adjacent discs will have slightly different strains hence a small shear between them.

Am I visualizing this right? At the point of the GW creation, N star collision in this case, the wave would be real powerful, like a tsunami, and would weaken as it expands?

The waves are not like a tsunami, more like a paddle mixer with two arms stirring a fluid. The waves created as the stars orbit round each other spread out and lose energy at the usual inverse square rate. We can measure the strain which is proportional to the root of the power so the amplitude of that falls as the inverse of the distance.

Dear George Dishman,

George>: The shear doesn't accumulate though space so take a line through the centre of the Earth pointing at the source and the atoms along that line are unmoving. The diameter increases or decreases symmetrically about that line and if you then think of the planet as made of thin disks perpendicular to that line, adjacent discs will have slightly different strains hence a small shear between them.

What makes space expand or decrease? When one volume expands then the volume next to that has to move aside. Look to your own video at vimeo. Where you have the contraction in equatorial direction and the expansion in the polar direction there the band is more extended towards the poles. When the band is expanded in the equatorial direction and contracted in the polar direction there the band is thinner. Why would an atom follow the differential when it would not follow the complete movement. The complete movement is the movement of the comoving coordinates. Any object that has no acceleration follows the movement of the comoving coordinates. They make the universe expand and take the galaxies with them. So why should they not take free hanging mirrors with them. The earth is too big for the wave and resists the movement. The mirrors are suspended special to follow the movement.

If a volume only would have the differential expansion then two adjacent volumes would overlap or separate. Both scenarios are impossible. We can't have space overlapping space and we can't have gaps in space. When you chose to have your mirrors at 4 km distance why they should sit in one volume unit and not in adjacent volumes that remain at constant distance? Can you see how the statement of only differential strain without full scale sheer leads on all sides to impossibilities.

When I think of the earth as disks then these disks resist to follow the movement of space. They move through space. The mirrors are designed to move with space. They didn't. So GRT failed.

Regards,

Paul Gradenwitz

Dear Paul,

PG: What makes space expand or decrease?

Talking about space "expanding" or "contracting" is an interpretation based on a choice of coordinates. The point of what I hope to write is that the concept of a "fabric of space" is a coordinate artefact.

PG: Any object that has no acceleration follows the movement of the comoving coordinates.

That's one interpretation. Alternatively we can say "Any object that has no external force applied must remain motionless due to inertia hence can be used as a fixed location in a coordinate system."

PG: Can you see how the statement of only differential strain without full scale sheer leads on all sides to impossibilities.

I can see you are being misled by applying a philosophy on top of the physics which was my original motivation for wanting to write something. I think my best course is to drop out of RG entirely for a while and get the work done.

PG: They move through space. The mirrors are designed to move with space.

You talk as if space were a material substance relative to which you could measure the motion of an object, that is a very common error.

Dear George Dishman,

Where you might to be forces to admit that GRT failed you opt to drop out. I would be glad if you continue to set it straight here.

We can have matter move through space at an unknown speed. That is why you say that LET and SRT have the same problem that we don't know the reference frame zero. But when there is accelerated expansion of space then matter can change the rate of expansion and matter will follow that change. In the same way the GW changes space and matter only can follow the differential distance change if it follows the large scale value. There is not increase in distance between galaxies if the Hubble flow would not move the most fare away galaxies at the largest speed. That same expansion only over a domain of the wave only can get a local increase in distance if the large scale movement is accordingly. That only can happen if matter moves with space without inertia while it moves through space with inertia. Both can happen on top of each other. That is the fact when objects have peculiar motion. I can set any coordinates that don't accelerate as the comoving coordinates. Then still, for each rest frame I get with that, the same conclusion will hold.

Regards,

Paul Gradenwitz

Dear Thierry De Mees,

Thierry>: "We can measure the strain" is absolute nonsense.

What is measured in the LIGO observatories is the phase shift of the lasers. That is related to the wavelength of the light and the path length between the mirrors. The signal then is expressed in the amount of strain that would be needed to get the exact same signal value. The energy is related to the surface. When the same energy is available over a larger area then it arrives at r^-2. The Strain is related to a one dimensional component of that energy. Thus it arrives with r^-1. That is no miracle but simple mathematics.

Regards,

Paul Gradenwitz

For an electrical signal, the power is proportional to the square of the voltage. If the power falls as r^-2, the electric field falls as r^-1.

For gravitational waves, power also falls as r^-2 and that is proportional to the square of the strain which falls as r^-1. There is a direct analogy.

Dear Thierry De Mees,

Thierry>: That is utter nonsense, George! You can never get more energy than what falls at the arrival, and that is r^-2.

Strain is no energy. It is a one dimensional measure of how much space has changed its dimensions. The energy is related to the surface. One square meter of the surface is expanded in x direction so that ∆x/x is the strain and in the same moment this surface is compressed in the y direction so that ∆y/y also is the strain. The square of the strain can be related to energy. The square of the strain falls with r^-2. That means the strain falls with r^-1. Measurement of the strain is no power measurement. It is amplitude measurement. Voltage is not related to power. Voltage squared is related to power. You can measure voltage. If the power decreases by a square function then the voltage decreases linear. Nothing special here.

Regards,

Paul Gradenwitz

Dear Thierry De Mees,

The LIGO observatories are designed to measure difference in configuration between two directions. You don't believe that they have observed events from cosmological origin. We have only few events. So you can continue with your disbelief for some time. At some moment it becomes outdated.

You can argue that the GRT description of shaking wobbling space doesn't exist. Then I follow. See my remarks in other posts. But the measurement is in one direction and thus related to amplitude and not to power. If power falls with r^-2 then amplitude falls with r^-1. No matter what really happens. What is measured is the amplitude. In my view LIGO proves that space doesn't behave as GRT describes it.

Regards,

Paul Gradenwitz

Dear Thierry De Mees,

That is your view. When they predict a source at the right distance then r^-2 would fail. The don't measure the force like g. So you can stay with your view. I don't share your view and still think that Einstein's GRT was proven wrong with LIGO.

If they would have tried to measure acceleration they would need a sensitivity for r^-2. They didn't do that. If you have problems with that, fine.

Regards,

Paul Gradenwitz

TDM: That is utter nonsense, George!

Really Thierry?

TDM: You can never get more energy than what falls at the arrival, and that is r^-2.

That's what I said, you just repeated me.

TDM: Whatever you try, if you measure the gravity acceleration "g" at the surface of the Earth, which is r^-2, ...

Right, but if you measure gravitational potential it falls as r^-1. For a GW, the energy falls as r^-2 but the strain falls as r^-1.

Strain gauges measure strain Thierry so you were wrong when you said strain couldn't be measured, think about what you say before you post. LIGO measures strain, not force and not energy.

Dear Thierry De Mees,

Space expands and contracts according to GRT. Objects move with space without extracting energy. There is no force needed to follow the expansion of space. Objects move through space while interacting with energy (inertia). There is force needed to change, accelerate, an object against the expansion of space. The strain is the effective local expansion of space. The light moving through space needs time to traverse a distance. When the distance has changed then the time it arrives also changes. That does not extract energy from space.

You insist that only energy can be measured. That would be true if the energy of the source is used to generate the signal.

I have shown that space can't have changed its shape for the GW. Thus I conclude that the observed phase shift has to originate from a local change in the propagation speed of light in an anisotropic way. Light that moves through this space will travel in a different speed for different directions. Again that effect will not extract energy from space.

How many correct predictions of optical events are needed till you accept that (at whatever method) the GW observatories can measure signals from cosmological events? Each chirp event is compared to the complete raw measurement data of the observation period to measure the likelihood that it was random data.

Regards,

Paul Gradenwitz

Dear Thierry De Mees,

Thierry>: "Space" as a physical entity doesn't exist. It cannot expand. That is utter nonsense.

I show what is the view of GRT. If you have seen my posts then I show that I agree with you that expanding space can't exist. The differential equations of GRT can't be integrated into full space. Only via a boost you can trace the reality.

If at some place a field has arrived then the potential difference in that field can be measured. Yet no energy out of the field can be used to alter some state of equipments in the case of GWs.

Is it correct that with even a load of cases where optical counterparts are predicted you will insist that the observations originate from Earthquakes even if there are no quake signals that resemble the chirp they search for?

Regards,

Paul Gradenwitz

Respected Expert Colleagues,

Thanks a lot for your valuable contributions, precious remarks, and respectable suggestions. The discussion now seems to be more interesting, significant, and productive.

Dear Thierry De Mees,

Thierry>: Since there no "potential difference" is measured, only forces (accelerations), there is no other solution than to accept that the energy amplitude felt with r-2 when it arrived on Earth. Hence, no possibility of reversing the measurement with r-1 until the source. Even when measuring in one direction.

I happen to disagree with you. The mirrors in the observatories didn't move. No forces, what so ever, changed their position during the transition of the GW. So, contrary to what is described with GRT, the mirrors didn't swing in their support. What the support did was the complete isolation of any force in one dimension.

What happened is that the properties of the vacuum changed. This made that the speed of light changed anisotropically. In one direction the speed of light increased while in the perpendicular direction the speed of light decreased. So while you expect an energy to make the mirrors move over ∆L, I explain it with change of the speed of light. Your method needs first energy to be transferred from the field to the mirrors and with r^-2 that would be impossible. My method has no energy transfer and the change in speed of light along one direction falls with r^-1. So that is indeed measurable.

Regards,

Paul Gradenwitz

Dear Thierry De Mees,

Thierry>: These assumptions are wrong, because waves only get their velocity by the physical properties of the medium that carries these waves.

You assume that the physical properties of the medium are invariant while I assume that they can change in a wave like manner. You are convinced that GW never can and will originate from cosmological events. With one event predicting a related observation your position is understandable, with several more your position will become more and more questionable.

Thierry>: There is only momentum and energy carried by waves, and that's all. We can only measure the effect of gravity, which is a force (acceleration), based upon the incoming values of energy and momentum, on Earth.

You can define what you think is the limited set of capabilities. You can't prove that this limited set is the complete set. Observational evidence can falsifies your statements. I expect that this in a growing number will happen. You don't believe that. Fine.

You still haven't given me evidence of an earthquake chirp and how it should enter the observatories. Your answer was an indication, by excluding the other source, that you can't come up with something better. That is not a positive evidence.

Regards,

Paul Gradenwitz

Respected Expert Colleagues,

Your valuable contributions and answers are very gratefully recognized.

Addition of URLs and references to replies may attract our another deep sense of gratitude.

Kind regards,

PK Karmakar

Tezpur University (Physics)

Dear Thierry De Mees,

Thierry>: I don't need to prove the Earthquake chirps to exist. You have to prove that they don't exist!

You needed to prove that oscillations in the support of the mirrors can reach the mirrors when the support structure is designed to reject exactly those vibrations in the frequency band of interest to a level of 10^-23. So, what earthquake event, that isn't measured by any earthquake measuring instrument, has the capability to raise its signal to overcome the isolation of the support structure. Be aware that they use earthquake detectors to actively isolate them like the noise canceling headphones use microphones to cancel external noise.

Thierry>: However, you seem to suggest that the medium is modulated by the event such as the wave itself is, which is wrong of course.

Yes I conclude that the medium seems to be modulated by the event. When space doesn't move nor ripple and thus the mirrors remain at a constant distance then a phase change in the measurement only can originate from the other component in the equations and that is the speed of light. You discard that with "of course". Maybe that modulation of the medium by the source is a new understanding of nature not yet taken into account by you. So be careful to discard it directly in such absolute manner.

Regards

Paul Gradenwitz

Dear Thierry De Mees,

Thierry>: You think so, dear Paul, that's all. With active noice cancelling, I still hear noice!

You miss one point. The active noise canceling is recorded and used as a flag to delete such signal from possible detections. If a chirp is present in the noise canceling path then a chirp detected in the main path is rejected.

If the mirrors moved through space during the detection event, then they would have extracted energy from the wave. Then your r^-2 would be valid. They didn't move through space thus they didn't extract energy. So your argumentation about energy fails.

Yes a modulation of the medium is called a wave. The vacuum propagation speed of EM waves is modulated by the GW. That is my explanation. Movement of EM through the vacuum does not extract energy from the vacuum towards the EM wave. So if the vacuum EM transmission speed is changed then the speed of light locally is different but moving light through that modified vacuum does not need energy from the GW wave to change the arrival time of the light at the other side of the track. Your r^-2 again is out of discussion. So, the total earth, where the wave fits inside several times, refuses to follow the interaction with the wave. That drains the wave of energy. Its amplitude will fall a bit. The lasers moving through the cavity don't drain the GW of energy. Isn't it interesting that these engineers found a method of information transfer where the information extraction is without energy transfer? You stick with an axiom that information always needs energy to transfer. You got outsmarted by some clever engineers.

Regards,

Paul Gradenwitz

Dear Thierry De Mees,

Thierry>: The last part is unreal. "The vacuum propagation speed of EM waves is modulated by the GW." No. There is not such a thing, that is a GRT invention. Besides, which EM waves? The allegedly detection is of GW alone.

That certainly is not a GRT invention. In GRT the speed of light is not modified. If you want to fight GRT then at least you should understand it good enough see that this statement is my statement and not at all a defence of GRT. The EM waves are the laser light in the LIGO tubes used to detect the GW. Think this concept through, see if there is a contradiction with the operation of the detectors. No mass is brought into movement so no energy is extracted from the GW.

Eclipses and more are brought up as explanation. They all need the path via seismic injection. The support rejects any injection with a large factor. Thus the injected, signal at support level, can be detected by seismic monitoring. I have seen these posts you point me at when they were actuality, was very interested, looked into them and came to the conclusion that they have not enough relevance.

Regards,

Paul Gradenwitz

Dear Thierry De Mees,

Since GW170817 I am no more interested in argumentation if these observatories can detect cosmological events but only in how they detect these events. You may need more such events but I doubt you ever will reach that level of confidence in these observatories.

Regards,

Paul Gradenwitz

Dear Thierry De Mees,

I think I am slowly increasing my understanding of what Gravity could be. This includes me realising that it is in fact possible to measure anisotropy of gravity without extracting energy of the field. This because light, EM waves, have no mass and thus can deviate without gaining or losing energy to the field of gravity. With this your attempt to declare that you need energy to make a measurement is not supported by me.

Regards,

Paul Gradenwitz

Dear Thierry De Mees,

Thierry>: No mass in the case of light doesn't mean no energy, dear Paul...

But it means that the light doesn't extract energy from the GW. The light finds the environment to travel through. That passage takes time. It starts the journey with a frequency. When the medium has a different ε₀μ₀ in the different directions, then the time it takes to make bridge that distance is different for the two directions. That doesn't take more energy from the vacuum then in the case the ε₀μ₀ is constant over time and isotropic.

Only where light has a border, where it interferes with matter, there this matter can take momentum from the gravitational filed. In the case of LIGO the arrival time recording through the phase shift takes energy from the light, not from the GW.

Regards,

Paul Gradenwitz

Dear Thierry De Mees,

Thierry>: Your theory, dear Paul, assumes that gravity waves would alter the medium in such way that the light waves would be altered as well. The question is if E-M waves effectively will, but it is a possible hypothesis.

And in that hypothesis the waves would traverse the medium that happens to be there. Thus the r^-1 is then possible. GWs were detected. That is my position. You don't believe that to be true. That is your position. I come with an explanation that allows for r^-1. You only can imagine a method of detection that needs r^-2 and conclude that since this is the only way that should be possible the detections never happened.

When Etha Carina would collapse then with your views about magneto-gravitation it would be possible that it would collapse into two close orbiting blackholes that then could spiral into one. That would give a large GW here where even r^-2 would work. (a lot of if's and when)

Regards,

Paul Gradenwitz

Dear Thierry De Mees,

You will remain to hammer on the r^-2 rule. LIGO will go on. By the way below this window when editing there is the symbol T². When you select the r-2 and then press that symbol then you get r^-2. Makes it better readable ;))

Regards,

Paul Gradenwitz

My role, dear Thierry, is observing and attempting to understand what is done. I cam to the conclusion that LIGO results are a pretty good proof that space doesn't bend.

We have subscripts superscripts and normal font. You can set the font size for your computer. I see this formatting I do as a service to the reader of my text.

Regards,

Paul Gradenwitz

Hi George, Paul, Thierry!

I think that one of the things that makes people uneasy about LIGO is that it's been hammered into us that as far as definitions for scientific work are concerned, distances are defined (international standards) by the amount of time that it takes light to cross them, and we are also told that any gravitational effect that changes nominal distances also changes the nominal speed of light in the region by the same amount, so that local observers are unaware (and unable to detect) that the speeds and distances have changed.

If the experimenter is put into a more dense gravitational environment, an outside onlooker sees the experimenter's atoms, and those of the experimenter's lab, appearing to be compacted more closely together as measured with background rulers. But the outside onlooker also measures the speed of light passing through the region (as measured with external clocks and rulers) to be slower (Shapiro effect), so that the experimenter is unable to detect the effect locally.

Similarly, if the experimenter is put in a less gravitationally dense environment, a distant onlooker can reckon that the experimental hardware's atoms are now further apart, but that the speed of light crossing the hardware is increased by precisely the same amount, so once again, the hardware is on principle unable to detect any change.

This principle of local lightspeed constancy suggests that if the experimental hardware is moved sufficiently slowly between the two different gravitational environments, that it should not be able to detect the gravitational change. Measurements taken before the start and after the end of the transition should produce identical results. We should only be able to measure effects due to a variation across the experimental hardware (including timelag effects).

This also suggests that if we have a dustcloud, and a gravity-wave washes across it, that the locally measured speeds of lightsignals between motes of dust should be unaffected, as the lightspeed change and the distance change obey the same law ... provided that the wavelength of the gravitational signal is much larger than the separation of the dust-particles used as references. As long as the measurement can still be called "local", there should be no local effect for hardware to measure.

This makes the idea of LIGO successfully measuring alterations in distance caused by gravity-waves, by bouncing light between known markers, slightly problematic.

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There are, however, two ways that we can progress with this:

Firstly, the atoms making up LIGO are not part of a floaty dustcloud – they are anchored to different parts of a nearby solid mass (the Earth), which is over 12,000 km "deep". If a gw with a wavelength much greater than that of the Earth sweeps across the planet, we might not be able to detect it ... but if a very short-wavelength gw passes through the Earth, the tidal stresses spanning a half-wavelength distance may partially resist the "anchored" atoms natural urge to wash about freely in the wave as they'd like to. While we still wouldn't be able to measure the expansion and contraction of the "true" distances across LIGO, we might be able to find an apparent measurable change as the wave sweeps though, due to the associated stresses in the Earth's crust preventing the end-reflectors from moving naturally in sympathy with the wave. We wouldn't be measuring the nominal distance across LIGO expanding and then contracting, but we might be able to measure an apparent contraction followed by an apparent expansion caused by the apparatus failing to expand and contract freely by the amount that it would if it was composed of small pieces drifting freely in space. If we're measuring LIGO's resistance to the gravity-wave rather than the wave itself, then we'll still get a waveform, but the phase will be off (inverted?). We will be measuring the effect of the differential flexing of the Earth's crust. We might also want to look out for an accompanying piezoelectric effect.

This is assuming (perhaps naively) that the higher-order time-variant aspects of the gravity-wave signal don't somehow create further effects that eliminate the physical stresses between different parts of the Earth experiencing different parts of the gw cycle.

The other way of bypassing the "no detectable local variation in c" rule is to look out for waves that are either smaller-wavelength than the apparatus, or at least small enough that there's a significant variation in gravitational properties across the apparatus, in which case we can say that the experiment no longer counts as a "local" experiment, and is allowed to report a result. The logging apparatus at one position is then allowed to "see" the physics at another position to be altered by the gravity-wave, due to the gravitational differential between those two positions due to the wave.

If LIGO's arms are 4km long, that seems to amount to 0.00001334 lightseconds , or ~1/74,962 of a lightsecond. That suggests that for a full wave to fit across LIGO it'd need to have a frequency of 75 kHz? And for a half-wave (max effect?) we'd expect peak detection for a gw at, ideally, at about 35 kHz?

GW150914 is quoted (wikipedia) as having "increased in frequency and amplitude in about 8 cycles from 35 Hz to 250 Hz "

Assuming that I haven't hit the wrong buttons on the calculator, that's LIGO intersecting with at best, what, between one thousandth to a one-hundred-and-fortieth of a waveform?

I've only read some of the popular accounts and a few papers, but I haven't seen any of these issues discussed. Perhaps they're dealt with in some engineering papers somewhere, but without seeing how these things were tackled in the design of LIGO, it's difficult to have an opinion on how well the hardware ought to operate. For instance: assuming that the reported waveform is "real", how much of the increase in amplitude during the chirp is due to increased amplitude at the source, and how much is due to the detector finding it easier to register the effects of shorter-wavelength GWs? Was the wavelength-sensitivity of the hardware included in the computer modelling? And does it appear correctly in the data?

Dear Eric Baird,

You wrote a long contribution with a lot of considerations. Let me take out of that one item, elaborate on that and see if you can understand that. Then we can continue. You keep track of what remains unclear to you and ask for that.

You talked about the floating dust cloud. That means you talk about a conglomeration of matter particles that are described such that they are not in physical contact with each other and in the time period of the GW passage have no significant movement with respect to each other so that any change of their mutual distance originates from the GW passage. That is a hypothetical cloud but it could help to describe how GRT might see the GW.

According to GRT the GW has the following effect. For any ring of matter the GW passage will make that it will change its shape in the plane perpendicular to the wave moving direction such that a circle becomes an ellipse with an area equal to the circle. I have added a picture of this. I want to stress that this is an attempt to describe the GRT view of the GW and thus I will in this moment not argue if that is what really happens or not.

The diameter of the ellipse in two directions is different. If we can find a method to measure this diameter distance difference, then we should be able to detect the GW. The setup of the LIGO detectors is such that there the mirrors are suspended from a support in a way that allows them to move freely in a plane perpendicular to the direction of gravity over a small distance. We thus could see this as that the mirrors would follow the effect of the GW on the dust particles in the direction perpendicular to the gravity vector of Earth at their location. The sensitivity to detect any changes in the light path configuration is maximised for the frequency domain that a GW of cosmological origin should have.

Can you follow my description and agree that this could be a GRT approach of how a GW would influence matter?

Regards,

Paul Gradenwitz

Gravitational waves can "be absorbed in space itself" i.e. in wave functions between bodies. The dark matter could be explained by O()-function of bouncing gravitational wave energy as long distance bound states. The energy from mass distribution changes would have been balanced as galactic bindings stored between and inside them.