# Shapiro (or Shapiro-like) delay of GW signals (split)

## Recommended Posts

Which would not be the case if Dan's model were correct. The delay would be fluctuating up and down. We should see additional modulation of the signal, but we don't.

That would require deciphering the math.

This has been answered numerous times. There is no separate Shapiro delay. If there was, we would not see the results that we saw.

If you or Dan disagree, then come up with a freaking model to predict what the waves should look like.

As far as doing a model I was trying to understand what would happen if we could take LIGO right alongside/into the BBH.

If it was at the barycenter between the two BHs the masses in each arm would get "pulled" apart (distance apart would increase) when the BH masses were aligned with the ends of the arms and closer together when the masses were at right angles. I'm sure that makes sense but tell me, would that be correct thinking?

Then, if the infall could take forever to allow us time to take the LIGO further and further away from the BBH but staying on the angular momentum vector, this toing and froing should continue but the amplitude will diminish. The alignment will depend on the speed/directness of gravity (can we draw straight lines or are they curves or whatever). The speed of gravity seems to be the difficult question for if gravity had to take a spiral path would light have to do the same? [That becomes more than I can comprehend]

Edited by Robittybob1

• Replies 144
• Created

#### Popular Days

Which would not be the case if Dan's model were correct. The delay would be fluctuating up and down. We should see additional modulation of the signal, but we don't.

That would require deciphering the math.

This has been answered numerous times. There is no separate Shapiro delay. If there was, we would not see the results that we saw.

If you or Dan disagree, then come up with a freaking model to predict what the waves should look like.

That would depend on a lot of factors, angle of inclination, orbital radius, precession and such. With the peaks always being spaced closer together as they infall it is really difficult to pick up even a microsecond change.

One day there will be a detection with a lower angle of inclination to the line of sight with more "linear polarization in its equatorial plane" and then we might see if there is any Shapiro time dilation.

##### Share on other sites

One day there will be a detection with a lower angle of inclination to the line of sight with more "linear polarization in its equatorial plane" and then we might see if there is any Shapiro time dilation.

There is no separate Shapiro delay. There can't be. It is impossible.

##### Share on other sites

There is no separate Shapiro delay. There can't be. It is impossible.

You are privileged to be able to answer like that. If one could tell where the gravity waves originates maybe we could see shapiro delay but atm we don't know if eclipsing a BH will be enough to make a block for the effect to go around and hence take a longer path.

##### Share on other sites

No Strange understands one aspect you and Dan choose to ignore.

The Einstein field equations already factor in time dilation effects.

That includes Shapiro delay.

I find it amazing how you two can ignore the equations (EFE) used on pages 6,7 and 8 which encompasses all coordinate orientations into 256 partial derivatives just under the

$T^{ij}$

coordinates.

The GRAVITY waves is the LOSS of Mass of the BINARY SYSTEM. Not the individual blackholes.

Edited by Mordred
##### Share on other sites

No Strange understands one aspect you and Dan choose to ignore.

The Einstein field equations already factor in time dilation effects.

That includes Shapiro delay.

You could be right, for if we have to use a line of sight argument we would have to be sure the GW was coming from the object behind it or the space behind it and we can't, so we will fail unless we can determine the source of the GW.

If it is effectively from a line between the binary masses, I think we still have a chance.

If we took the LIGO right up to the binary the end of arm that pointed toward the barycenter would experience the greatest G force so the test particles would move apart particularly when they were in the eclipsed position.

So eclipsing is not the answer.

##### Share on other sites

The region between the two BH's is of a higher energy/density due to the spacetime curvature stress tensor.

This region effectively has a mass of its own.

See the Einstein ring.

http://astrobites.org/2014/11/04/what-would-a-binary-black-hole-merger-look-like/

The Einstein ring is the spacetime distortions surrounding both BHs

Here lets refer to the following statement.

"Imagine observing a distant binary star and trying to measure the gravitational field at

your location. It is the sum of the field from the two individual components of the binary,

located at distances r1 and r2 from you. As the binary evolves in its orbit, the masses change their position with respect to you,

and so the gravitational field must change. "

The gravitational field is the regions inside and surrounding the Einstein ring. As its energy/density will gradually fall off to the background spacetime.

If you look on page 6 Under

Compact Binary system. The third equation applies the above statement.

http://www.physics.usu.edu/Wheeler/GenRel2013/Notes/GravitationalWaves.pdf

What this means is any change within this system in angular monentum (including the average momentum of the particles within the system) can produce gravity waves.

A good example is looking for gravity waves in the CMB.

You could be right, for if we have to use a line of sight argument we would have to be sure the GW was coming from the object behind it or the space behind it and we can't, so we will fail unless we can determine the source of the GW.

If it is effectively from a line between the binary masses, I think we still have a chance.

If we took the LIGO right up to the binary the end of arm that pointed toward the barycenter would experience the greatest G force so the test particles would move apart particularly when they were in the eclipsed position.

So eclipsing is not the answer.

This isn't quite accurate. A BH doesn't lose mass from inside it's event horizon. (Except through Hawking radiation) The mass used to generate a G wave is from the surrounding spacetime. Including but not limiited to the accretion disk.

In a binary system this is any higher energy/density region from the background metric.

Aka the higher gravitational field from a flat Euclidean background field. This is why we define the system via the Einstein field equations and why there is no possibility of Shapiro delay.

Edited by Mordred
##### Share on other sites

No .....

The GRAVITY waves is the LOSS of Mass of the BINARY SYSTEM. Not the individual blackholes.

@Mordred - where did you get that statement from? It wasn't in the "Gravitational Waves" teaching aid.http://www.physics.usu.edu/Wheeler/GenRel2013/Notes/GravitationalWaves.pdf

You make it sound the binary system has more mass than the BHs do. Is that their gravitational potential energy and their kinetic energy as well as their rest mass?

Could briefly explain what you mean please?

Edited by Robittybob1
##### Share on other sites

As far as doing a model I was trying to understand what would happen if we could take LIGO right alongside/into the BBH.

But that's not what we're talking about here. Go speculate about that in another thread.

That would depend on a lot of factors, angle of inclination, orbital radius, precession and such.

True, but there are two points to be made here. One is you can simplify the models (e.g. assume no precession). The other is that if you don't have a model, how can anyone possibly insist that it explains the signals?

With the peaks always being spaced closer together as they infall it is really difficult to pick up even a microsecond change.

WTF are you talking about? Dan was quoting Shapiro delays of ms up to several seconds, and the data we have is not spaced as close together as a microsecond.

##### Share on other sites

Careful study.... (years of studying)

(Yes some of what I claim is outside a single article... call it experience)

Lets ask a question. What is the difference between a plasma cloud and a rock? The short answer density. (Aside from the particle closeness allows other interactions... strong and electromagnetic binding energy).

Point being although the BH itself has greater density. Doesn't mean lower density relations in a larger volume cannot generate similar effects.

Add the factor that any information beyond the EH (ie Mass) is lost to the system.

Gravity propogates at speed of c. So it is equally affected by the geodesic equations that apply to light. Neither light nor mass escapes the EH (except via Hawking radiation).

A simple line conclusion is that the surrounding regions outside the EH of each BH must be involved. (Excluding the mass inside the EH, which cannot escape...)

Mass is an extremely misleading term.

Probably the most accurate definition is "resistance to inertia change

The mass of the Earth can create a BH. If it's volume falls under its Schwartzchild radius. Or even that a rock.

Well let's just look at the amount of mass / energy is contained in just the accretion disk.

(Careful it's a 900 page coverage)

http://arxiv.org/abs/1104.5499 :''Black hole Accretion Disk'' -Handy article on accretion disk measurements provides a technical compilation of measurements involving the disk itself.

You can have the mass of entire Suns outside the EH. In the accretion disk. Only a percentage falls beyond the EH. The rest being radiated away via the jets

Edited by Mordred
##### Share on other sites

But that's not what we're talking about here. Go speculate about that in another thread.

True, but there are two points to be made here. One is you can simplify the models (e.g. assume no precession). The other is that if you don't have a model, how can anyone possibly insist that it explains the signals?

WTF are you talking about? Dan was quoting Shapiro delays of ms up to several seconds, and the data we have is not spaced as close together as a microsecond.

This was supposed to be DanMP's thread and I'm not advocating Shapiro TD but I appreciated that it was split off and allowed to be discussed separately.

The last one was a rushed post as we were going out, and I probably didn't use enough words to explain my thoughts fully.

"With the peaks always being spaced closer together as they infall it is really difficult to pick up even a microsecond change."

What I was trying to say:

So do you agree with the first bit? "the peaks always being spaced closer together as they (the BHs) infall" the frequency rises.

But that frequency change is exponential (or something like that) so it is difficult to just say what the frequency is at any one moment to the next. In my understanding in the time it takes to form one wave, the "chirp" frequency may have risen by much more than 1hz maybe as much as 20-40 Hz per orbit. I can't just look at the wave of the "chirp" and mentally predict where the next wave is expected so how could you tell visually if the wave was out by 1 ms? (I should have said "millisecond" not "microsecond" sorry).

So if Shapiro TD was possible (which is now doubtful??) and it just delayed part of a wave by less than a millisecond, how would one be able to see it in the GW 150914 "chirp" waveform?

##### Share on other sites

But that frequency change is exponential (or something like that) so it is difficult to just say what the frequency is at any one moment to the next.

There are ways of analysing waveforms to answer this sort of question; such as Fourier transforms. As such, there is not a single frequency but an infinite number of frequencies.

I can't just look at the wave of the "chirp" and mentally predict where the next wave is expected so how could you tell visually if the wave was out by 1 ms?

Which is why I said that doing this was a waste of time.

However, if there had been that large a discrepancy between theory and measurement then it would have been highlighted in the results.

But, of course, any distortions of space-time that would have caused a Shapiro delay for passing light have already been included in the modelling of the gravitational waves.

##### Share on other sites

How does some range of delays to electromagnetic radiation relate to the creation of gravitational waves? ...

Gravity propogates at speed of c. So it is equally affected by the geodesic equations that apply to light.

So, part of the gravity from the BH behind, gets to Earth passing just outside the EH of the BH in front, with a Shapiro-like time delay. The delay can be bigger than the whole "chirp", so it's like a big "chunk" of mass (many time the solar mass) disappeared and reappeared twice per orbit, during the chirp. As far as I understand, the frequency of the one and only signal we received (GW150914) was twice the orbital one. You can call it irelevant but I don't. It is a big variation in gravitational pull, so it can be called gravitational wave. How this relates with GR calculations for the GWs in this BBH, I don't know. Maybe it was included. Or maybe there are different things but with the same frequency, twice the orbital frequency. Let's wait for other, better signals to find the truth. I don't have all the answers, sorry. Do you? How you included dark energy, dark matter and Higgs field in your equations? According to wikipedia

The standard model of cosmology indicates that the total mass–energy of the universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy.[3][4]

Edited by DanMP
##### Share on other sites

What does the above have to do with Shapiro delay? The average energy/density of the intergalactic and interstellar medium isn't sufficient to cause a delay.

##### Share on other sites

This was supposed to be DanMP's thread and I'm not advocating Shapiro TD but I appreciated that it was split off and allowed to be discussed separately.

The last one was a rushed post as we were going out, and I probably didn't use enough words to explain my thoughts fully.

"With the peaks always being spaced closer together as they infall it is really difficult to pick up even a microsecond change."

What I was trying to say:

So do you agree with the first bit? "the peaks always being spaced closer together as they (the BHs) infall" the frequency rises.

But that frequency change is exponential (or something like that) so it is difficult to just say what the frequency is at any one moment to the next. In my understanding in the time it takes to form one wave, the "chirp" frequency may have risen by much more than 1hz maybe as much as 20-40 Hz per orbit. I can't just look at the wave of the "chirp" and mentally predict where the next wave is expected so how could you tell visually if the wave was out by 1 ms? (I should have said "millisecond" not "microsecond" sorry).

So if Shapiro TD was possible (which is now doubtful??) and it just delayed part of a wave by less than a millisecond, how would one be able to see it in the GW 150914 "chirp" waveform?

It wouldn't, which point YET AGAIN to why we need a calculation, but as the assertion is that this is not negligible, we are proceeding under the assumption that it is larger.

So, consider this: the delay is larger and measurable. When the signal passes each BH, it is delayed by 100 ms. The delay gets much smaller when you go another π/4 into the rotation. Now the GW signal has gone through π/2 of its cycle, so lets assume it has gone from a max to a min. The minimum is delayed 100 ms less than the max – so the min and max on this cycle should be bunched together an extra 100 ms (and the curve distorted). Now the next quarter rotation happens, and the delay increases. The next maximum is now delayed the additional 100ms. So it should be further in time from the previous minimum. Repeat. You should see this modulation on the signal

Do we see it? No, we don't.

The claim is that this is a big effect, and yet we don't see it. The claim is without merit. Either the effect is small, or nonexistent. The theory says it is nonexistent (misapplied concept that's already included in GR)

What does the above have to do with Shapiro delay? The average energy/density of the intergalactic and interstellar medium isn't sufficient to cause a delay.

And even if it had some effect, it would be well away from the signal source and not cause any issue. This alleged effect can only happen in proximity to the binary system.

##### Share on other sites

I've already covered that no single BH generates the wave signal. Is that somehow to complex for you?

The wave signal is generated by the spacetime curvature encompassing BOTH BH's. Come on Dan I even referred you to the correct pages and math

You really need to stop making assumtions the math behind chirp frequency is included in the article I've continously reposted.

Obviously you didn't even look at the math. Or understand it.

If you did you would realize that there cannot be a Shapiro delay.

Oh wait I forgot, the paper argues and counters your personal theory therefore it must be wrong

Well fine PROVE thousands of professional physicists wrong ...

SHOW the MATH supporting your argument

Edited by Mordred
##### Share on other sites

It wouldn't, which point YET AGAIN to why we need a calculation, but as the assertion is that this is not negligible, we are proceeding under the assumption that it is larger.

So, consider this: the delay is larger and measurable. When the signal passes each BH, it is delayed by 100 ms. The delay gets much smaller when you go another π/4 into the rotation. Now the GW signal has gone through π/2 of its cycle, so lets assume it has gone from a max to a min. The minimum is delayed 100 ms less than the max – so the min and max on this cycle should be bunched together an extra 100 ms (and the curve distorted). Now the next quarter rotation happens, and the delay increases. The next maximum is now delayed the additional 100ms. So it should be further in time from the previous minimum. Repeat. You should see this modulation on the signal

Do we see it? No, we don't.

The claim is that this is a big effect, and yet we don't see it. The claim is without merit. Either the effect is small, or nonexistent. The theory says it is nonexistent (misapplied concept that's already included in GR)

And even if it had some effect, it would be well away from the signal source and not cause any issue. This alleged effect can only happen in proximity to the binary system.

The Shapiro TD was found using light so if we just for a moment consider light rather than gravity for a while and then go back to gravity. I think this is valid for gravity and light travel at the same speed, so will light coming past the BH close to the photosphere show STD?

In the final outcome it still must be a fail for more mass never blocks gravity but it definitely blocks light, so I don't see how we are ever going to get STD but hang on there is Gravitational time delay so gravity might be able to time delay the GW that passes through the BH itself! Now that is possible and has the same cause and effect too isn't it? [i'm not making claims but trying to see possibilities here.] Can a GW go through a BH?

Would you get a GW blackout if it can't? (When the line of sight is an eclipse.)

I understand what you are saying but I can't see a time delay of that magnitude being important for it is only ever a small fraction of the light or gravity (LoG) that will be affected. You will still have the normal chirp with a small amount of delayed GW hidden in this more massive signal, that any STDed GW is just lost somewhere in the signal as a type of background noise. With light you can pass it through tubes etc to isolate parts of it but that can't be done for gravity, so you will never isolate STD gravity from the background noise. There is plenty of background noise and where is that coming from? Was it partly STD gravity wave signals, who knows?

Edited by Robittybob1
##### Share on other sites

Could you ever get the gravity wave to pass back through the mass that caused it in the first place? There are two gravity waves per orbit so could it be the first wave interfering with the production of the second wave?

It would all depend on the speed of gravity. Will the velocity dependent terms be cancelled within the BBH and gravity act as if it was virtually instantaneous?

Is this another mental twister?

I'd say it is impossible to get one BH around to the other side of the orbit to become affected by its own gravity. For that to happen it would have to be travelling faster than the SoL.

But it could be moving fast enough to be experiencing a gravitational pull that is not directed from CoM from one body to the CoM of the other.

So what situation will cause a Shapiro time delay of gravity?

If it happens it will be happening all the time. Can we ever measure it? We would have to know what position we'd need to be in.

Wikipedia discusses Shapiro time delay in connection to GWshttps://en.wikipedia.org/wiki/Shapiro_delay#Shapiro_delay_of_neutrinos_and_gravitational_waves

Shapiro delay of neutrinos and gravitational waves
From the near-simultaneous observations of neutrinos and photons from SN 1987A, the Shapiro delay for high-energy neutrinos must be the same as that for photons to within 10%, consistent with recent estimates of the neutrino mass which imply that those neutrinos were moving at very close to the speed of light. Since gravitational waves were only directly detected in 2016, there is as yet no data on the Shapiro delay for gravitational waves. In general relativity and other metric theories of gravity, though, the Shapiro delay for gravitational waves is expected to be the same as that for light and neutrinos. However, in theories such as tensor-vector-scalar gravity and other modified GR theories which reproduce Milgrom's law and avoid the need for dark matter, the Shapiro delay for gravitational waves is much smaller than that for neutrinos or photons.

No footnotes but further links are provided.

I still imagine they are talking about GWs passing nearby a third massive body and not the two bodies that produced the GW.

So we would need the BBH to infall when it was being inline with the edge of the Sun and the LIGO would need to be in a sensitive position on the Earth. All in all a very unlikely coincidental set of events.

.

Edited by Robittybob1
##### Share on other sites

So, part of the gravity from the BH behind, gets to Earth passing just outside the EH of the BH in front, with a Shapiro-like time delay. The delay can be bigger than the whole "chirp", so it's like a big "chunk" of mass (many time the solar mass) disappeared and reappeared twice per orbit, during the chirp.

Except it didn't "disappear".

As far as I understand, the frequency of the one and only signal we received (GW150914) was twice the orbital one.

That is hardly surprising: the orbital frequency was calculated as half the frequency of the signal.

It is a big variation in gravitational pull, so it can be called gravitational wave.

You have yet to show that this claimed effect matches either the theoretical predictions or the observations. As such, there is not reason to take it seriously.

How this relates with GR calculations for the GWs in this BBH, I don't know.

And that seems to b a large part of the problem.

Maybe it was included.

Of course it was. Or perhaps you would like to show an alternative to the Einstein Field Equations that reproduce all the effects of GR but not Shapiro delay. Then use that to predict the behaviour of black holes. And then add back a delay caused by GR (but ignoring all the other effects of GR).

Do you begin to see how silly that sounds?

Let's wait for other, better signals to find the truth.

This has nothing to do with "truth".

How you included dark energy, dark matter and Higgs field in your equations? According to wikipedia

What makes you think they need to be included?

So what situation will cause a Shapiro time delay of gravity?

If it happens it will be happening all the time. Can we ever measure it? We would have to know what position we'd need to be in.

Light passing a black hole would show the Shapiro delay. So would gravitational waves. Detecting this would require a fairly continuous source of gravitational waves that was then occulted by a large mass. You would then see a phase shift in the signal as the mass passed in front of it. I imagine we are many decades from being able to make those sort of observations, never mind the probability of such an occultation happening.

You say "You need mass." so was that like the Sun in the path of the GW? For there is plenty of mass in the BBH. So where abouts do we need this mass please? I read up about Shapiro time delay and that "mass" in their case seemed to be the Sun. So could we use the sun again in this case of a GW? We don't know precisely where GW150914 was so it seems impossible to nominate some other mass that the wave passed. I just fail to see how EFE could have taken all these factors into account.

What assurance can Mordred give me that this is in the GR equations?

Dan is not talking about some third mass that the waves might have passed. Any such mass (and there may have been many galaxies in between us and this event) would not have been included in the calculations (as they are not relevant to the generation of gravitational waves). They also would have been static during the period of the detected signal and so can be ignored.

Edited by Strange
##### Share on other sites

Aren't both bodies being accelerated in their orbit? They are not traveling in a straight line but following an ellipse so they don't have a constant velocity. Please in what frame of reference are they traveling with constant velocity?

You don't seem to reading what is written. He was describing objects that do not generate gravitational waves, not these or similar black holes.

"Not all objects emit gravity waves. Any symmetric rotating object of constant velocity will not produce waves."

##### Share on other sites

You don't seem to reading what is written. He was describing objects that do not generate gravitational waves, not these or similar black holes.

"Not all objects emit gravity waves. Any symmetric rotating object of constant velocity will not produce waves."

In the whole quote http://www.scienceforums.net/topic/93995-shapiro-or-shapiro-like-delay-of-gw-signals-split/page-3#entry911378 he is talking about these BHs

.... Now in the Binary BH scenario NEITHER BH produces gravity waves. They are both symmetric rotating objects.

The gravity waves emitted is due to the changes of the assymmetric spacetime changes encompassing BOTH BHs.

So the Shapiro delay will be the same for all measurement points on the chirp signal.

Not all objects emit gravity waves. Any symmetric rotating object of constant velocity will not produce waves.

Were the black holes in GW150914 moving at a constant velocity? I accept that a "symmetric rotating object of constant velocity will not produce waves". I was just questioning whether the BHs in a binary orbit are moving at a constant velocity.

@Strange - Were the BHs moving at a constant velocity?

##### Share on other sites

In the whole quote http://www.scienceforums.net/topic/93995-shapiro-or-shapiro-like-delay-of-gw-signals-split/page-3#entry911378 he is talking about these BHs

Were the black holes in GW150914 moving at a constant velocity? I accept that a "symmetric rotating object of constant velocity will not produce waves". I was just questioning whether the BHs in a binary orbit are moving at a constant velocity.

@Strange - Were the BHs moving at a constant velocity?

Of course they weren't: they were in orbit and therefore accelerating. Their orbits were getting faster so they weren't at a constant speed, either.

But they are not in the set of things that don't generate gravitational waves and so are not covered by the clause "symmetric rotating object of constant velocity".

##### Share on other sites

This

Of course they weren't: they were in orbit and therefore accelerating. Their orbits were getting faster so they weren't at a constant speed, either.

But they are not in the set of things that don't generate gravitational waves and so are not covered by the clause "symmetric rotating object of constant velocity".

Mordred states "Now in the Binary BH scenario NEITHER BH produces gravity waves. They are both symmetric rotating objects."

Are they really "symmetric rotating objects"? So is he saying each BH is accelerating but neither produces a gravity wave?

Wikipedia states : https://en.wikipedia.org/wiki/Gravitational_wave#Sources

In general terms, gravitational waves are radiated by objects whose motion involves acceleration, provided that the motion is not perfectly spherically symmetric (like an expanding or contracting sphere) or rotationally symmetric (like a spinning disk or sphere). A simple example of this principle is a spinning dumbbell. If the dumbbell spins around its axis of symmetry, it will not radiate gravitational waves; if it tumbles end over end, as in the case of two planets orbiting each other, it will radiate gravitational waves.

It is unfortunate they use words like "objects", so I would say a BH is an object. "in the case of two planets orbiting each other, it will radiate gravitational waves." It is also unfortunate that they used the plural "waves". Should they have said "in the case of two planets orbiting each other, they will radiate a single gravitational wave"?

Maybe they say "waves" because there are two waves per orbit for the binary?

Wikipedia basically states each orbiting object will radiate waves.

.

Edited by Robittybob1
##### Share on other sites

!

Moderator Note

Questions about the mainstream physics of Shapiro delay have been split

This thread is about the conjecture of the OP. Please: STAY ON %#&*!@ TOPIC

(IOW, if your sentence should have a question mark at the end, and it's not directed at the OP, seriously weigh whether you are going off on a tangent.)

##### Share on other sites

Mordred states "Now in the Binary BH scenario NEITHER BH produces gravity waves.

Correct. The system generates graviational waves.

Wikipedia basically states each orbiting object will radiate waves.

No it doesn't. It says "it" (singular) will generate gravitational waves. "It" is very clearly the pair of objects which can be compared to a dumbbell.

It is also unfortunate that they used the plural "waves". Should they have said "in the case of two planets orbiting each other, they will radiate a single gravitational wave"?

Of course not. It will radiate continuously, as long as it is spinning.

##### Share on other sites

This topic is now closed to further replies.

×