Can LIGO actually detect gravitational waves?

[aramis720]

Did I state anything about lines? I asked you to place 4 coordinates onto the surface of the balloon.

 

If you compress along the y axis, the total volume of air inside the balloon remains unchanged.

 

Therefore the y axis must expand to conserve the total volume of air.

 

Rudimentary elementary school physics.

That's not my metaphor that I was asking about. Again: envision two perpendicular lines on the surface of a balloon (a 2D version of an interferometer). Now expand the balloon. Will the length of either line change in any detectable way using the lines themselves? Of course they won't b/c they're expanding in exactly the same way as the balloon. Now expand the metaphor to three dimensions.

[Mordred]

That's not my metaphor that I was asking about. Again: envision two perpendicular lines on the surface of a balloon (a 2D version of an interferometer). Now expand the balloon. Will the length of either line change in any detectable way using the lines themselves? Of course they won't b/c they're expanding in exactly the same way as the balloon. Now expand the metaphor to three dimensions.

We are not expanding the total volume.

 

We are measuring the effective lengths along each axis.

 

If the total volume changes then yes both will be identical.

 

A GW does not change total volume so no the two axis do not expand or contract identically

Edited July 7, 2017 by Mordred

[aramis720]

We are not expanding the total volume.

 

We are measuring the effective lengths along each axis.

 

If the total volume changes then yes both will be identical.

 

A GW does not change total volume

You didn't address my metaphor still. I can't force you But I think it might be helpful. Do you agree that in my metaphor there is no detectable expansion using the perpendicular lines?

[Mordred]

Forget this nonsense.

 

this is pointless talking to you.

 

If you cannot understand the basics such as posted its useless.

 

Do the experiment. draw a friggen ruler on each axis.

 

Squeeze then measure the change at times t1,r2,t3...

Edited July 7, 2017 by Mordred

[aramis720]

Forget this nonsense.

 

this is pointless talking to you.

Wait, you're refusing to address my simple visual metaphor? Why would you not address this question after our long discussion?

[Mordred]

Because your not listening.

 

At time t1. 1 axis contracts, at precisely the same time the other expands.

 

Done cut and dry. Both axis are not expanding or contracting at the same time.

 

Total volume is preserved. aka conservation laws. The total number of particles within the affected region remain unchanged. The total density is also unchanged. (key note total).

 

Edit more accurately average density.

Edited July 7, 2017 by Mordred

[beecee]

https://www.quora.com/If-gravitational-wave-affects-light-how-does-LIGO-prevent-its-lasers-from-being-affected

 

Answer:

"A gravitational wave stretches space in one direction and contracts it in the other direction. [*] The interferometers measure the distance between the mirrors, so LIGO is looking for a periodic expansion and contraction of the two path lengths (hence being affected).

[*] Specifically if the gravitational wave is traveling is going in the Z direction, it will contract space in the X direction and expand it in the Y direction and then reverse it half a period later".

 

 

https://www.quora.com/If-light-follows-spacetime-how-did-the-LIGO-experiment-find-that-a-gravitational-wave-passed-over-Didnt-the-path-of-light-also-change#!n=12

 

Answer:

"The detection of gravity waves has nothing to do with light following space-time (whatever that means). It is a simple consequence of gravity-induced contraction. You see, just as motion causes the FitzGerald-Lorentz contraction, so gravity also causes contraction. In fact the detection of gravity waves was done with an apparatus similar to the Michelson apparatus that demonstrated the F=L contraction. Here’s the description from my book (see quantum-field-theory.net):

“In 2015 gravity waves were detected directly at LIGO (Laser Interferometer Gravitational-Wave Observatory) by measuring the contraction of one arm of an apparatus, as compared with another arm at right angles. The arms were 4 km long and the laser beam was made to traverse the paths almost 500 times, giving a total travel distance of over 1000 km. This experiment captured the imagination of the public and will stand as one of the great feats of experimental physics, alongside the famous Michelson-Morley experiment of 1887, which it resembles (see fig. 7-1 below). In fact, when you read the description of the M-M experiment you will see that the LIGO experiment is not as hard to understand as you thought. The field nature of gravity and the existence of gravitational waves were now established beyond any doubt.”

Edited July 7, 2017 by beecee

[aramis720]

Because your not listening.

 

At time t1. 1 axis contracts, at precisely the same time the other expands.

 

Done cut and dry. Both axis are not expanding or contracting at the same time.

 

Total volume is preserved. aka conservation laws. The total number of particles within the affected region remain unchanged. The total density is also unchanged. (key note total).

 

Edit more accurately average density.

So how would you know that one axis contracted and the other expanded in my 2D visual metaphor, by using the perpendicular lines only?

[Mordred]

Place coordinates on those lines. then measure the change in scale (expansion, contraction between coordinates).

 

Or just watch how the circles contract and expand in this video youtube.

 

https://www.google.ca/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DaVFf8UcX1A8&ved=0ahUKEwj3-LySnvjUAhVM94MKHa2wBogQwqsBCCUwAg&usg=AFQjCNFEWWMMa1G4HoTqXxbKJCLB4wRfAA

 

See there is a lot going on there simultaneously.

Edited July 7, 2017 by Mordred

[beecee]

Wait, you're refusing to address my simple visual metaphor? Why would you not address this question after our long discussion?

And yet you continue to ignore my advice and E-Mail aLIGO? [since you appear unsatisfied with the many reasonable answers you have received here, which most certainly have addressed all your fabricated anomalies]

[aramis720]

Place coordinates on those lines. then measure the change in scale (expansion, contraction between coordinates).

 

Or just watch how the circles contract and expand in this video youtube.

 

https://www.google.ca/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DaVFf8UcX1A8&ved=0ahUKEwj3-LySnvjUAhVM94MKHa2wBogQwqsBCCUwAg&usg=AFQjCNFEWWMMa1G4HoTqXxbKJCLB4wRfAA

By definition the coordinates on the perpendicular lines won't change in a detectable manner no matter how much the balloon is distorted. Do you agree? They will simply expand or contract in a manner that is entirely undetectable based on the perpendicular lines themselves.

[Mordred]

GR IS A COORDINATE SYSTEM. LINES HAVE NO MEANING WITHOUT COORDINATES.

 

spacetime is coordinates not lines.

 

Blooming bugger even the references your posting are telling you your wrong.

Edited July 7, 2017 by Mordred

[aramis720]

GR IS A COORDINATE SYSTEM. LINES HAVE NO MEANING WITHOUT COORDINATES.

 

spacetime is coordinates not lines.

 

Blooming bugger even the referencedms your posting are telling you your wrong.

That's not my point. Again, staying with the 2D metaphor: if you expand or contract the balloon do you agree that there is no way to measure this expansion or contraction using just the perpendicular lines? Please don't move ahead of this point. I'm trying to establish where we agree and then explore where we start to disagree.

[Mordred]

Your point does not apply under GR. period.

 

By the way when you measure your using coordinates. So you setup a premise "You cannot measure without coordinates " equals true. But then how do you apply that to spacetime "metric"?

Edited July 7, 2017 by Mordred

[aramis720]

Your point does not apply under GR. period.

 

By the way when you measure your using coordinates.

So do you agree with my point about the 2D metaphor?

[Mordred]

Stupid as it is your not able to apply that to spacetime. No offense but that is the most insanely stupid argument I have ever heard on a forum.

 

You cannot describe spacetime changes without coordinates.

Edited July 7, 2017 by Mordred

[aramis720]

Stupid as it is your not able to apply that to spacetime. No offense but that is the most insanely stupid argument I have ever heard on a forum.

 

You cannot describe spacetime changes without coordinates.

I didn't say anything about not using coordinates. You misunderstood me. Again: do you agree that any coordinates on the perpendicular lines in the 2D metaphor can't be used to detect any expansion or contraction of the balloon because they will expand and contract exactly the same amount as the balloon itself?

[Mordred]

I didn't say anything about not using coordinates. You misunderstood me. Again: do you agree that any coordinates on the perpendicular lines in the 2D metaphor can't be used to detect any expansion or contraction of the balloon because they will expand and contract exactly the same amount as the balloon itself?

You must describe the changes in coordinate of all axis at precisely the same time.

 

The changes are NOT IDENTICAL.

.

 

Done I'm finished with you

[swansont]

my point this whole time, is that any device in space that is designed to measure waves OF space will be distorted in exactly the same way as the space it occupies, making detection in principle impossible. Is that clear?

 

It's been pointed out that this is not the case. Light does not travel the same way massive objects do.

[aramis720]

You must describe the changes in coordinate of all axis at precisely the same time.

 

The changes are NOT IDENTICAL.

.

 

Done I'm finished with you

Thanks for the dialogue Mordred. I'd hoped we could at least work through this 2D metaphor but no problem if you're not game. Think it through some more and you may see my broader point about the comparable 3D interferometer difficulties.

It's been pointed out that this is not the case. Light does not travel the same way massive objects do.

We've been focusing on the Faraoni 2007 explanation here in the last week and his argument is that the mirror positions do in fact move from the GWs, but that light wavelength is not affected. I've been trying to get to the bottom of the notion that the mirrors move by using a 2D metaphor as a simplification of the 3D/4D reality. Since Mordred has decided not to continue with the dialogue I'd appreciate any further thoughts you have. Do you agree that the coordinates on the perpendicular lines drawn on the balloon's surface can't be used to detect any expansion or contraction of the balloon itself b/c they change exactly the same amount as the balloon?

[beecee]

Thanks for the dialogue Mordred. I'd hoped we could at least work through this 2D metaphor but no problem if you're not game. Think it through some more and you may see my broader point about the comparable 3D interferometer difficulties.

 

More to the point, it appears that you are obviously not game to do what I suggested way back.......

 

That's not my point. Again, staying with the 2D metaphor: if you expand or contract the balloon do you agree that there is no way to measure this expansion or contraction using just the perpendicular lines? Please don't move ahead of this point. I'm trying to establish where we agree and then explore where we start to disagree.

 

And more ignoring of what I suggested if you are not convinced of the answers you have received here...plus of course any balloon expansion analogy is far different to gravitational waves and what they entail.

 

Science forums such as this and most others are open to any Tom, Dick and Harry, that are able to claim what they like, without any mathematical support, or dispute already validated science, and without listening to answers given.

It changes nothing. The results stand as is.

Do you agree that the coordinates on the perpendicular lines drawn on the balloon's surface can't be used to detect any expansion or contraction of the balloon itself b/c they change exactly the same amount as the balloon?

 

as answered in post 274......

aLIGO is not measuring expansion or contraction of spacetime...it is measuring ripples/waves/undulations in spacetime.

And each arm sees those undulations/waves in different phases, eg: peaks and troughs.

Your analogy is invalid and your questions answered many times, including post 282.

[aramis720]

We've been focusing on the Faraoni 2007 explanation here in the last week and his argument is that the mirror positions do in fact as a result of the GWs, but that light wavelength is not affected by the GWs. I've been trying to get to the bottom of the notion that the mirrors move by using a 2D metaphor as a simplification of the 3D/4D reality: two perpendicular lines drawn on the surface of a balloon, with coordinates drawn on the lines. I'd appreciate any further thoughts anyone has on this. Do you agree that the coordinates on the perpendicular lines drawn on the balloon's surface can't be used to detect any expansion or contraction of the balloon itself b/c they change in exactly the same ways as the balloon? If so, why would it be different when we go to the 3D/4D actual interferometer?

 

I've argued that it wouldn't b/c the meter stick (the interferometer arms and their effect on the light fringe phase) itself is changing to exactly the same degree that space and spacetime are being distorted. It doesn't matter in what way we distort the balloon in the 2D metaphor, or the underlying space or spacetime in the 3D/4D reality, if we are in fact using a "meter stick" (the interferometer in these examples) that is itself situated in the dimensional reality that is changing. To measure such changes we need an additional degree of freedom, a higher dimension. So in the 2D example we need a third dimension to be able to measure the change, as we can achieve in our own 3D reality by actually performing the balloon experiment with perpendicular lines drawn on it. And to measure the 3D/4D changes created by grav. waves in our actual reality we'll need a higher dimensional vantage point that alas is not available to us as mere 3D/4D dwellers.

Edited July 8, 2017 by aramis720

[beecee]

Here is some answers by a professional involved with the aLIGO GW detection/s and his reply to supposed anomalies by at least other experts...................

 

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

 

The results stand, and deservedly so after all possible contingencies and supposed anomalies have been accounted for.

Just a thought from an interesting lay person: The obvious incorrect claim being made in this thread, has certainly been invalidated and put to rest, but I have just thought of another issue. The three GW detections so far have all been BH mergers, but each detection is/was unique in distances from us, the sizes of the BH's and I would hazard a guess, the size of the chirp or noise....

So one would ask the question of our doubting Thomas, if what he imagined was valid, why the three distinct chirps and the various BH sizes in each instant.

 

 

An illustration as to how the waves affected each arm differently at......about a third of the way down the page...

https://www.theverge.com/2017/6/1/15714908/gravitational-waves-black-holes-third-detection-ligo

 

An illustration of how LIGO detects gravitational waves when they pass the observatories. Image: American Museum of Natural History

Edited July 8, 2017 by beecee

[Strange]

I said it doesn't matter what direction the waves are coming from -- it could be any or all directions and 1 or a hundred different waves. Based on simple logic, if the apparatus that occupies space is stretched to exactly the same degree as the space it occupies it cannot detect the waves. Think it through. It will sink in eventually.

The physical apparatus is affected one way the light is affected differently. What don't you understand about that?

 

Or do you just refuse to accept it, despite informal and mathematical explanations? What (religious?) beliefs do you have that make it impossible for you to accept a mathematical result?

[aramis720]

Strange, I've addressed in detail in this thread (last week) why the argument that apparatus and light are affected differently doesn't add up. So now I'm seeking clarity on why the mirrors are thought to move. And I've suggested the 2D thought experiment with lines on a balloon as a way to start with the basics. Can you answer my question about that? Do you agree that any expansion or contraction of the balloon will not be detectable using the lines themselves or any coordinate system based on the lines? And if so why wouldn't this apply equally to the 3D version? I'm not asking you to repeat prior points or give me equations. I'm asking you to think about it from a basic logical perspective.