Can LIGO actually detect gravitational waves?

[swansont]

That is exactly where I think you are underestimating the promise of gravity wave study. There is a complete difference in the strain of space at point A and point B 5,000 miiles away as a wave is coming through, and every 20th of a second this situation is flipped.

 

 

But that is only a difference in phase, related by the distance and the speed of light. The same can be said for the two detectors already in use — you have to shift the time axis to get the curves to overlap. IOW, a sine wave is "completely different" at different values of x or t (unless you are separated by 2π in time or distance), but the curve that is traced out over time is identical. And since we are not looking at a snapshot but a graph over time, this difference is moot. You will end up with exactly the same curve. No new data other than triangulation at some level of error. And since (as I believe you've pointed out) we can't detect the merger optically, knowing precisely where it happened is of minimal use.

[tar]

SwansonT,

 

Understood. But what you say only matters in an amplitude modulation analogy. In a frequency modulation setting, at the peak of the chirp, when the BHs are spiraling together, there is information in the double integral, or double derivative (which ever way that goes, I forget.) And in this case, when you overlap the second long black wave form, with a detector 196,000 miles upstream, you would find the complex just starting in the one case, while just finishing in the other. So the same event would be noticed at both locations, but not the same portion of the wave complex, and analyzing these types of aspects of the wave is exactly the kind of pursuit that will yield information about what it means to be a quadrapole wave in 3D space, squishing and stretching the place as you go.

 

Regards, TAR

And having an understanding of the changing contour of space while a GW is coming through allows a one second window, the next time a wave comes through to perform other EM experiments, within the waveform. Surf it.

 

AND if the wave started pure and simple, assuming that it is still pure and simple, rejects the possibility that it has been affected by the space through which it has traveled, including the occasional bits of space being warped by masses and other GWs.

 

Regards, TAR

and suppose you have two detectors receiving the wave at the same time, as in not upstream of the other, but next to the other, or at some angle to the wave front, somewhat like getting your eye right up next to the corner of the garage and looking across the face, to notice any contour, from flat, that might be present

Edited June 17, 2017 by tar

[swansont]

SwansonT,

 

Understood. But what you say only matters in an amplitude modulation analogy. In a frequency modulation setting, at the peak of the chirp, when the BHs are spiraling together, there is information in the double integral, or double derivative (which ever way that goes, I forget.) And in this case, when you overlap the second long black wave form, with a detector 196,000 miles upstream, you would find the complex just starting in the one case, while just finishing in the other. So the same event would be noticed at both locations, but not the same portion of the wave complex, and analyzing these types of aspects of the wave is exactly the kind of pursuit that will yield information about what it means to be a quadrapole wave in 3D space, squishing and stretching the place as you go.

 

Let's see the math.

 

Also, how did 196,000 miles enter into this? You were talking about detectors closer together than the current LIGO system.

[tar]

SwansonT,

 

I have no math.

 

I do not know how gravity waves work.

 

Regards, TAR

[Strange]

I do not know how gravity waves work.

 

 

Then maybe you shouldn't be lecturing everyone about them.

[tar]

OK

[Mordred]

Still good to ask about them. Good way to learn. Though obviously learning the math is the best route.

Edited June 17, 2017 by Mordred

[Strange]

Still good to ask about them. Good way to learn.

 

 

Absolutely. Asking is good.

 

Telling people that they are doing it all wrong? Not so good.

[Mordred]

Telling require a clear clut model with precise and predictive dynamics. Sorry that requires a clear cut methodologuly of modelling.

 

Not as easily stated as placed into a practicum. Take a simple set of atractive and repulsive force. When one studies the mathematics. A homogeneous and isotropic distribution is simple.

 

Add a diverse range of anistropic action and holy man, you better understand the math as there is absolutely no hope in seeing the dimemsionsality of property relations without it

 

P.S: side note I got serious studying physics in the early 80's. Forum discussions have changed dramatically since then. Particularly in GR and subsequently the FLRW metric itself coupled with the thermodynamic applications of particle physics.

 

when one truly learns the intensity of interconnected mathematical models. Only then can one understand the dynamics we can measure

Edited June 18, 2017 by Mordred

[tar]

SwansonT,

 

If I had a math for the situation I think it would have to be based on a different vector calculus than we usually use.

 

For the last three years or so my mental 3D space has been aligned to the twelve sections of the sphere built around the geometry of an almadine garnet, (it turns out.)

 

A 6 axis isometric grid.

 

Vector matrix calculus based on such a six axis figure would, in my estimation form a "better" view of the kind of squishing and stretching space is capable of, as a dense packed matrix of spheres can be modeled with intersecting hexagonal and square planes that would keep their anistropic relationship in all directions.

 

Alas, I have no practicum, with which to describe my ideas.

 

But it surrounds the need I have for more than three stations. I would like six, with one of the arms of each, along one of the six axis.

 

Perhaps this could be built in space, or at six appropriate places on the surface of our sphere. The direction is important, the timing is important, but I don't mean to lecture anyone, I am just trying to imagine what is happening to space as a gw comes through...what are the implications...what has to be the case, since the world HAS TO fit together flawlessly.

 

Regards, TAR

[swansont]

SwansonT,

 

If I had a math for the situation I think it would have to be based on a different vector calculus than we usually use.

 

 

Doesn't matter. The answer would have to work out the same.

[tar]

swansont,

Understood, any point in space can be located with 3 dimensions and a fourth time dimension can be charted by mathematically wedging in a 45 degree, so plotting something on 6 axis gains you nothing, the point in space can still be located. But I am envisioning a 3d matrix where both 90degrees and 60degrees are present in the relationship between any single point, and its isotropically related 12 neighbors. Same grid of course can be found with x,y,z coordinates, but here you surround yourself with a cube, and look at the middle of the twelve edges, not the eight corners. Same space, same reality, and as you say you would get the same answer, but you can ask a more detailed question with more detailed directional and timebased information.

 

 

What for instance is this?

 

 

 

A giraffe passing by a second floor window

 

 

The data we get from each LIGO, or VIRGO is somewhat noisy, and when one goes to line it up with the others one does not know whether to delay or advance the black line to get the picture of the waves. And how much to compress or expand the lines to show an accurate portrayal. With six axis to line up, one gets both clues as to the matchup, and once aligned can see details of the waves that would have been thrown out as noise.

 

Maybe.

 

If you are matching a template, you just find the carrier. If you are picturing the carrier you have a better chance of seeing an unknown signal on it

 

Regards, TAR

 

 

 

 

for instance, suppose the wave has characteristics that triangulate to a source in a particular direction as if a flat plane came through with the source merger being the cause of the characteristics and this source was 1.3 billion lyrs away, but figuring in the curvature of the Earth, and the direction from which the wave had to come, there is another characteristic in the wave that triangulates to a source in the same direction, but only 1 ly away. Perhaps the characteristic was caused by a gw that passed through Earth in the other direction, two years ago

[Strange]

This article addresses a specific challenge to the LIGO results, but also answers some of tar's questions.

 

Particularly, the question: "why not look at the raw data instead of using models or templates?" Well, it turns out they do. I had missed that when looking at the results before.

 

http://www.preposterousuniverse.com/blog/2017/06/18/a-response-to-on-the-time-lags-of-the-ligo-signals-guest-post/

 

 

Finally, LIGO runs “unmodelled” searches, which do not search for specific signals, but instead look for any coherent non-Gaussian behaviour in the observatories. These searches actually were the first to find GW150914, and did so with remarkably consistent parameters to the modelled searches, something which we would not expect to be true if the modelled searches are “missing” some parts of the signal.

[swansont]

for instance, suppose the wave has characteristics that triangulate to a source in a particular direction as if a flat plane came through with the source merger being the cause of the characteristics and this source was 1.3 billion lyrs away, but figuring in the curvature of the Earth, and the direction from which the wave had to come, there is another characteristic in the wave that triangulates to a source in the same direction, but only 1 ly away. Perhaps the characteristic was caused by a gw that passed through Earth in the other direction, two years ago

I would believe it if you showed math that showed that this could happen. As it stands, though, this is entirely too hand-wavy, and contrary to my experience with geometry and algebra. (and astronomy. 1 LY away?)

[tar]

swansont,

 

I admit it is real handwavy but it goes to the consideration of how confident are we in the data. That is, how "clear" is the data. Can we see signals within the signal that we are not expecting, or can we only see what we are expecting to see?

 

My "math" to suggest one might be able to pickup a gw crossing another gw 1 ly away is a general figuring that a gw gradient stayed coherent after traveling 1.3billion lys and is "spread out" in terms of power in an inversed cubed type of way that results in the wave (initially with the force of the mass of multiple suns turned instantly to energy) only having the power to distort space the width of a partial proton over the distance leveraged by the experiment, yet we can read the effect that this distortion has on space through monitoring the interference of some EM waves that took two orthogonal routes to the detector...whereas the gw we sense today HAD to either have been crossed by or is soon to be crossed by another GW that we just saw or are about to see. So the impulse, the wave of one gw should be embedded in the next. And this fluctuation, this "interference" had to happen within a couple lys of here because the two waves crossed earth within a year of each other. So space is curved within curved space, and the interaction should still have some coherence because relatively few other GWs have had a chance to add or subtract their impulse, and the interaction had to be a billion times closer than the original gradients.

 

But again, I am trying to box in the answer to the thread question. Either we can pick up GWs or we can't. If we can, then we can make further study of them, and possibly use them as probes of space...able to in essence "feel" the universe around us. And while having a fourth, or building 12, would be stupid if we cannot detect GWs, if we CAN detect GWs we should be able to learn a lot more about gravity than we know today, by studying in detail, GW waves. If we can see a strong one from 1.3 billion lys, mathwise, we should be able to see a weak one from 1 ly.

 

Regards, TAR

I am having a hard time, mentally. figuring what the intersection of two GWs would look like in space. It would not be one event, but an infinite number of events happening continually, at an infinite number of locations, within, at a particular instant, that area of space where the two expanding shells coexisted. So while one GW passes through a spot on Earth in a sec, another portion of that expanding shell has to already be passing through another "close" GW...so depending on how precisely we can see one wave embedded in the prior, or the next, we might, with 12 detectors, be able to map gravity waves that passed through already, before we had any detectors up. (by reading the record of other gws on the passing one)

Edited June 19, 2017 by tar

[Strange]

I am having a hard time, mentally. figuring what the intersection of two GWs would look like in space.

 

 

I am not surprised. I would not be surprised if the only way to know is to run a massive simulation on a supercomputer.

[tar]

I just thought experimented away my expanding shell image. Or have another question. When two BHs are spiraling in on each other, is there an orbital plane, or is it a crazy 3d dance like an electron orbit? That is, if you are positioned at a pole of a gradient event caused by a flat orbit, and the two masses were the very close together that they would have had to be to get around each other 20 times in a sec at max .6 c. then you would see no wave, where to see the full wave you should be on the equator of the dance. The power of the wave would be mostly on the plane of the equator...?

or at least on the plane of the last orbit

so what assumptions are made about the shape of an expanding impulse?

like a gamma ray burst is sort of aimed like a spreading shot gun pattern, where you can be within range of the blast, but missed, does a GW expand out in sort of an expanding ring, where you could be within range of the merger, but be missed by the ring?

Edited June 19, 2017 by tar

[Strange]

so what assumptions are made about the shape of an expanding impulse?

 

 

No assumptions are made. The interaction is modelled to find the form that the gravitational waves take. The waves are strongest in the (equatorial) plane of the orbits and weakest in the direction of the axis of the orbits. (This may complicated slightly by the spin of the black holes as I think it depends on the total angular momentum of the system, not just the axis of the orbits.)

 

(OK. A few assumptions are made in the analysis: that GR is correct, is the main one. Also that the orbits are nearly circular.)

[tar]

if the gradient energy stayed on the plane, mostly coherently for billions of lys, then the thickness of the plane would be max the diameter of the larger of the two BHs, and the diameter of the larger of the two had to be much less than the travel path of either mass during that last second which at .6C would be 118,000 miles

[Strange]

if the gradient energy stayed on the plane, mostly coherently for billions of lys,

 

 

It doesn't. The first signal detected in 2015 was thought to be from a pair of black holes where the orbital axis was nearly along the line of site (with about 30° if I remember correctly). A stronger signal would have been detected if the system had been "edge on".

[swansont]

swansont,

 

I admit it is real handwavy but it goes to the consideration of how confident are we in the data. That is, how "clear" is the data. Can we see signals within the signal that we are not expecting, or can we only see what we are expecting to see?

 

My "math" to suggest one might be able to pickup a gw crossing another gw 1 ly away is a general figuring that a gw gradient stayed coherent after traveling 1.3billion lys and is "spread out" in terms of power in an inversed cubed type of way that results in the wave (initially with the force of the mass of multiple suns turned instantly to energy) only having the power to distort space the width of a partial proton over the distance leveraged by the experiment, yet we can read the effect that this distortion has on space through monitoring the interference of some EM waves that took two orthogonal routes to the detector...whereas the gw we sense today HAD to either have been crossed by or is soon to be crossed by another GW that we just saw or are about to see. So the impulse, the wave of one gw should be embedded in the next.

Not in any measurable way, as has been discussed. The chirp is a light-second in length. 3 x 10^5 km. If there's any effect, you stretch or shrink that by a part in 10^-18. The pulse becomes ~10^-16 m shorter or longer. Its duration changes by nanoseconds. Undetectable.

 

And this fluctuation, this "interference" had to happen within a couple lys of here because the two waves crossed earth within a year of each other. So space is curved within curved space, and the interaction should still have some coherence because relatively few other GWs have had a chance to add or subtract their impulse, and the interaction had to be a billion times closer than the original gradients.

 

Undetectable.

 

But again, I am trying to box in the answer to the thread question. Either we can pick up GWs or we can't. If we can, then we can make further study of them, and possibly use them as probes of space...able to in essence "feel" the universe around us. And while having a fourth, or building 12, would be stupid if we cannot detect GWs, if we CAN detect GWs we should be able to learn a lot more about gravity than we know today, by studying in detail, GW waves. If we can see a strong one from 1.3 billion lys, mathwise, we should be able to see a weak one from 1 ly.

 

There will be no GWs from a LY away since there isn't any appreciable mass at that distance, doing anything that would emit them. A little while ago we discussed scaling. Perhaps you could go back and review that. You need a huge amount of mass, and appreciable acceleration, to get anything we could detect. Only a handful of the binary pulsars we can observe emit enough gravitational radiation to potentially see their orbits degrade over the years, and that's not nearly enough to detect with LIGO.

 

I am having a hard time, mentally. figuring what the intersection of two GWs would look like in space. It would not be one event, but an infinite number of events happening continually, at an infinite number of locations, within, at a particular instant, that area of space where the two expanding shells coexisted. So while one GW passes through a spot on Earth in a sec, another portion of that expanding shell has to already be passing through another "close" GW...so depending on how precisely we can see one wave embedded in the prior, or the next, we might, with 12 detectors, be able to map gravity waves that passed through already, before we had any detectors up. (by reading the record of other gws on the passing one)

Ripples on a pond might be a good starter for visualizing interference. The waves do not become embedded. You have no basis for continuing to make that claim.

[tar]

so the strong wave would be in a plane less than 6 thousand miles thick, expanding out in that plane, the chances of that thin ring intersecting another thin ring of the same sort might be good, but it would only happen twice, for any two rings, max and this is definitely not enough interaction to be seen from 1ly which is the closest such an interaction could be and its imprint would NOT be on the part of the next ring that came through Earth from another direction...so SwansonT you are absolutely correct, there is no way to sense an intersection of two gws 1ly away. My expanding shell model is not how it would be. It is expanding rings.

[swansont]

if the gradient energy stayed on the plane, mostly coherently for billions of lys, then the thickness of the plane would be max the diameter of the larger of the two BHs, and the diameter of the larger of the two had to be much less than the travel path of either mass during that last second which at .6C would be 118,000 miles

 

 

Where are you getting 118,000 miles?

[tar]

.6c

[swansont]

.6c

 

 

That's a speed, not a distance. How are you getting that number as a distance regarding two black holes orbiting each other?