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

[DanMP]

According to @AstroKatie (Katie Mack, an astrophysicist), the radiation is strongest perpendicular to the orbital plane

Was that a joke?

Not a joke, just a misunderstanding. Read here where and how is the right answer.

 

If the line of sight is perpendicular to the orbital plane (0^o or 180^o in the figure), the signal is 0 or close to 0. Close to 0 is also seen from the orbital plane (90^o). "The best fit shows the angle between the line of sight and the angular momentum vector of the system is about 150 degrees".

 

With this problem solved, I can finally reveal my simple, logical, intuitive explanation for GWs:

 

Black holes (BHs) are surrounded by "gravity wells". If gravity "travels" with the speed of light, then close to a BH, we should have/see a delay, as in Shapiro time delay. If this delay is big enough (minutes, hours), in the final seconds before merging, the "gravity well" of the BH in the front appear to mask the gravity pull of the BH in the back. So we have/"see" M1+M2 when the BH's are side by side and M1 or M2 when they are one in front of the other. This alternance of apparent mass produces the waves, the signal we detected.

 

This is in agreement with relativity (Shapiro delay is explained by GR). Also, it explains the frequency and the fact that on the perpendicular the signal is close to 0. The fact that in the orbital plane the signal is also close to 0 is due to the fact that there is a common "gravity well" that delays and distorts the signal. Why this is not happening in the line of sight (150 degree) it can be easily explain with my relativity (the delay & distortion is smaller above that line/angle).

 

Robittybob1, are you satisfied with my logical explanation?

 

 

mod edit (17Mar)

!

Moderator Note

 

This has been split from the main forum discussion on Gravitational waves

http://www.scienceforums.net/topic/93472-gravitational-lens-and-gravitational-waves-question/

 

[Strange]

Not a joke, just a misunderstanding. Read here where and how is the right answer.

 

That is about the probable angle of the orbital plane to our line of site, not the direction that gravitational waves are emitted.

 

If the line of sight is perpendicular to the orbital plane (0^o or 180^o in the figure), the signal is 0 or close to 0. Close to 0 is also seen from the orbital plane (90^o).

 

Wrong. The radiation is strongest in the direction perpendicular to the orbital plane (i.e. aligned with the angular momentum). And not zero in the orbital plane.

http://www.aei.mpg.de/~schutz/download/lectures/AzoresCosmology/Schutz.AzoresLecture2.pdf

 

 

Black holes (BHs) are surrounded by "gravity wells". If gravity "travels" with the speed of light, then close to a BH, we should have/see a delay, as in Shapiro time delay.

 

Please keep your made-up "stuff" to the Speculations forum.

 

Why this is not happening in the line of sight

 

Except it obviously is happening in the line of sight ... because we detected it. Duh.

[Phi for All]

With this problem solved, I can finally reveal my simple, logical, intuitive explanation for GWs:

 

!

Moderator Note

Not in this thread, and not in mainstream Relativity either. If you want to reveal your alternative, please do so in Speculations, in its own thread. Please follow the rules, we have them for many reasons, and we have special ones for Speculations. Please make sure to abide by them, again for many reasons.

 

Don't pursue this here. Don't respond to this modnote, but Report it if you object.

[DanMP]

That is about the probable angle of the orbital plane to our line of site, not the direction that gravitational waves are emitted.

Yes, you are right (thank you), it's about the probable angle of the orbital plane with our line of site for the signal we received. As I read in your link (thanks again), perpendicular to the orbital plane "both polarisations are present but are out of phase, so this represents purely circularly polarised radiation". Along the x-axis "is pure +-polarised radiation". "At directions between the ones we have calculated there will be a mixture of polarisations, which leads to a general elliptically polarised wave. By measuring the polarisation received, a detector (or network of detectors) can measure the angle of inclination of the orbital plane of the binary to the line of sight."

 

So, my simple explanation is valid only (or mainly) for the (one and only) signal we received. For now and for this thread is enough. Maybe I will get back to it later, in another thread.

 

About "made-up stuff", Shapiro delay is in mainstream Relativity and the idea that gravity travels with the speed of light is taken from here:

 

"As the binary evolves in its orbit, the masses change their position with respect to you,

and so the gravitational field must change. It takes time for that information to propagate

from the binary to you — t_propagate = d/c, where d is the luminosity distance to the binary."

 

(the link was posted by swansont, see #50 - thank you swansont).

[swansont]

 

About "made-up stuff", Shapiro delay is in mainstream Relativity and the idea that gravity travels with the speed of light is taken from here:

 

"As the binary evolves in its orbit, the masses change their position with respect to you,

and so the gravitational field must change. It takes time for that information to propagate

from the binary to you — t_propagate = d/c, where d is the luminosity distance to the binary."

 

(the link was posted by swansont, see #50 - thank you swansont).

 

 

t=d/c has nothing to do with the Shapiro delay. How big would these delay times be, and how would they change? What would be important would be changes in the Shapiro delay; whatever delay you have from any individual BH would simply be an added constant to the signal.

[DanMP]

t=d/c has nothing to do with the Shapiro delay.

If the information (about mass, gravitational field, etc.) from BH-1 propagates as light does in free space, with constant speed c, than, if light is Shapiro delayed near a BH, that information from BH-1 may also be Shapiro delayed when it passes near BH-2 (placed between BH-1 and the Earth).

 

How big would these delay times be[?]

I don't know exactly (it depends on BH mass and how near it passes), but if the delay is bigger then the whole "chirp" (few seconds?), the information (gravity pull) from BH-1 when is behind BH-2 would arrive (long) after the chirp, giving the impression that BH-1 disappeared ... The same is valid with BH-2 pull when it gets behind BH-1. This is a good (extra) reason for a GW:

 

Far from a source (like the aforementioned binary) we see the gravitational radiation field

oscillating and these propagating oscillating disturbances are called gravitational waves.

By the way, if this Shapiro delay idea is not good/important, then we should have big enough GWs from there long before the chirp/merger, because the BHs are moving fast enough long before the "crush". Did they record them?

 

My Shapiro delay idea has (maximum) effect only when the BHs are very close to each other, right before they merge, as it happened ... The angle of observation was also just right for such an effect ... Do you think that it was a coincidence?

[Strange]

I don't know exactly (it depends on BH mass and how near it passes), but if the delay is bigger then the whole "chirp" (few seconds?), the information (gravity pull) from BH-1 when is behind BH-2 would arrive (long) after the chirp, giving the impression that BH-1 disappeared ...

 

Can you show us the calculations that support this being a significant factor that needs to be taken into account?

 

My Shapiro delay idea has (maximum) effect only when the BHs are very close to each other, right before they merge, as it happened ... The angle of observation was also just right for such an effect ... Do you think that it was a coincidence?

 

From your description, it sounds as if this effect (if it exists) would only be relevant for gravitational waves that are detected "edge-on". But that is not the orientation in the LIGO detection. (And gravitational waves are strongest at right angles to that direction anyway.)

[swansont]

If the information (about mass, gravitational field, etc.) from BH-1 propagates as light does in free space, with constant speed c, than, if light is Shapiro delayed near a BH, that information from BH-1 may also be Shapiro delayed when it passes near BH-2 (placed between BH-1 and the Earth).

 

 

How is that relevant to this discussion? That is not the geometry in this situation.

[DanMP]

Can you show us the calculations that support this being a significant factor that needs to be taken into account?

If light goes very close to a BH, it never gets out. When it passes far enough, there is no delay. So, from a certain distance, with a certain orientation (angle), the delay may be bigger than "the chirp".

 

From your description, it sounds as if this effect (if it exists) would only be relevant for gravitational waves that are detected "edge-on". But that is not the orientation in the LIGO detection. (And gravitational waves are strongest at right angles to that direction anyway.)

150 degrees (as it probably was) may be good enough, see above.

[swansont]

If light goes very close to a BH, it never gets out. When it passes far enough, there is no delay. So, from a certain distance, with a certain orientation (angle), the delay may be bigger than "the chirp".

 

 

Which is why a calculation is required.

[Strange]

If light goes very close to a BH, it never gets out. When it passes far enough, there is no delay. So, from a certain distance, with a certain orientation (angle), the delay may be bigger than "the chirp".

 

Or it may not.

 

I'm going with "not" as I haven't seen anything to suggest otherwise. I have read several papers on black hole mergers, including skimming the papers on the recent detection and none of them have ever mentioned this as a possible factor.

 

150 degrees (as it probably was) may be good enough, see above.

 

At that angle neither black hole is even close to being behind the other, so your speculation seems to be irrelevant.

[swansont]

Thing is that the Shapiro delay only drops off logarithmically with distance (1/ln(d)), so even if it is appreciable, the important value will be how much it changes.

 

Also, it occurs to me that this scenario depend on the gravitational radiation being emitted by each body, rather than the system. Nobody has established that this is the case.

[Robittybob1]

 

 

Which is why a calculation is required.

What are the things needed for this calculation? @Dan are you thinking gravity is delayed as light was delayed?

[Strange]

What are the things needed for this calculation?

 

I have no idea. The Wikipedia page gives a simple approximation but notes that it is not applicable to situations involving black holes.

 

Dan are you thinking gravity is delayed as light was delayed?

 

Exactly. Gravitational waves travel through space-time and so any curvature of space-time will affect them in the same way that light is affected.

What are the things needed for this calculation?

 

This paper might give you some ideas: http://iopscience.iop.org/article/10.1086/310835/fulltext/5332.text.html

"Our calculations demonstrate that, for reasonably compact and eccentric orbits, rotation of a sufficiently massive BH companion to the orbiting pulsar leads to approximately microsecond-order departures from pulse arrival times"

[swansont]

What are the things needed for this calculation?

 

 

Not sure. My objection is the insistence that the effect is important, while no analysis has been done. Which seems to be happening a lot, lately.

[Robittybob1]

 

 

Not sure. My objection is the insistence that the effect is important, while no analysis has been done. Which seems to be happening a lot, lately.

I find we are in the middle of this most exciting break through, the discovery of gravitational waves and all the information is available on the internet. It is truly amazing.

In that other thread I wanted to understand what causes the loss of momentum leading to the decayed orbit, it would be hard to think that the Shapiro Time Delay (STD) would have anything to do with it but who knows?

 

I have no idea. The Wikipedia page gives a simple approximation but notes that it is not applicable to situations involving black holes.

 

Exactly. Gravitational waves travel through space-time and so any curvature of space-time will affect them in the same way that light is affected.

 

This paper might give you some ideas: http://iopscience.iop.org/article/10.1086/310835/fulltext/5332.text.html

"Our calculations demonstrate that, for reasonably compact and eccentric orbits, rotation of a sufficiently massive BH companion to the orbiting pulsar leads to approximately microsecond-order departures from pulse arrival times"

Does the STD affect the speed or direction of gravity at the level of the binary orbits too? (gravitational lensing effect and the STD effects combing somehow?)

Edited March 15, 2016 by Robittybob1

[Strange]

Does the STD affect the speed or direction of gravity at the level of the binary orbits too? (gravitational lensing effect and the STD effects combing somehow?)

 

It may do, in principle, but my guess (until evidence is presented to the contrary) is that the effect is immeasurably small (i.e. less than the noise/errors in the measurements).

[Robittybob1]

 

It may do, in principle, but my guess (until evidence is presented to the contrary) is that the effect is immeasurably small (i.e. less than the noise/errors in the measurements).

@Strange I was meaning right at the site where the two merged, not necessarily at the LIGO detectors. But no doubt we will need to consider both. Do you think we need to start another thread specifically on the Shapiro Time Delay Effect?

[Strange]

@Strange I was meaning right at the site where the two merged, not necessarily at the LIGO detectors. But no doubt we will need to consider both.

 

Surely a time delay is a time delay; it will be the same wherever you measure it.

 

 

Do you think we need to start another thread specifically on the Shapiro Time Delay Effect?

 

I can't imagine why. It is just another crackpot idea from another random crackpot.

[Robittybob1]

 

Surely a time delay is a time delay; it will be the same wherever you measure it.

 

 

I can't imagine why. It is just another crackpot idea from another random crackpot.

Time delay at the LIGO depend on things like direction of line of sight. If you don't know where the signal is coming from you don't know how much of the delay was due to the position, The precession of the BBH affects the position of the nodes (where the GW signal will be strongest. So how will you get LIGO to pick it up, so it will only be theoretical.

What happens to light may not happen to gravity, but you could look at the effects if it was.

 

Is DanMP a crackpot? His estimate of the strength of the STD effect seemed rather high, but that in itself is not enough to reject the idea.

[swansont]

What happens to light may not happen to gravity, but you could look at the effects if it was.

 

In this case, that would be brand-new physics and not under consideration for such an experiment.

 

I find we are in the middle of this most exciting break through, the discovery of gravitational waves and all the information is available on the internet. It is truly amazing.

In that other thread I wanted to understand what causes the loss of momentum leading to the decayed orbit, it would be hard to think that the Shapiro Time Delay (STD) would have anything to do with it but who knows?

Who knows? Hmmm, physicists, maybe?

[Robittybob1]

 

 

In this case, that would be brand-new physics and not under consideration for such an experiment.

 

 

Who knows? Hmmm, physicists, maybe?

I'm looking for that physicist. Kip Thorne has tried to explain it "Kip S. Thorne-Gravitational Waves: A New Window onto the Universe" YT

 

but...

Edited March 15, 2016 by Robittybob1

[swansont]

It may do, in principle, but my guess (until evidence is presented to the contrary) is that the effect is immeasurably small (i.e. less than the noise/errors in the measurements).

 

For a signal going past the sun it's about 200 microseconds. But that's for a signal going past the sun. It has no been established that this situation is present with a binary black hole — that we are getting two signals, one from each BH. It's conjecture by two people that this is so, but this is unsupported conjecture, i.e. no reference to scientific literature. (and that's what is needed, because we're discussing this in relativity, not speculations).

 

(If this was a signal from two sources, there would be interference effects — modulations on the carrier frequency — that are AFAICT not observed. But that's not a discussion for here)

 

Basically it's up to DanMP to provide evidence that this is an issue.

[Strange]

Do you think we need to start another thread specifically on the Shapiro Time Delay Effect?

 

If you do feel the need to start one then, before you do, make sure that:

 

1. You have convincing evidence that it is relevant to this situation (i.e. that there is an independent "signal" from each black hole); and

2. You know how to calculate the Shapiro delay in an extreme case like that of a spinning black hole.

[Robittybob1]

 

For a signal going past the sun it's about 200 microseconds. But that's for a signal going past the sun. It has no been established that this situation is present with a binary black hole — that we are getting two signals, one from each BH. It's conjecture by two people that this is so, but this is unsupported conjecture, i.e. no reference to scientific literature. (and that's what is needed, because we're discussing this in relativity, not speculations).

 

(If this was a signal from two sources, there would be interference effects — modulations on the carrier frequency — that are AFAICT not observed. But that's not a discussion for here)

 

Basically it's up to DanMP to provide evidence that this is an issue.

I thought you had accepted that there were two waves coming from the quadrupole.

 

If you do feel the need to start one then, before you do, make sure that:

 

1. You have convincing evidence that it is relevant to this situation (i.e. that there is an independent "signal" from each black hole); and

2. You know how to calculate the Shapiro delay in an extreme case like that of a spinning black hole.

I was thinking if it was proven by DanMP it would be hidden within a thread on a different topic. It is not my baby but Dan's.

Edited March 15, 2016 by Robittybob1