Questions about Shapiro delay (split from speculations thread)

[swansont]

!

Moderator Note

Split from http://www.scienceforums.net/topic/93995-shapiro-or-shapiro-like-delay-of-gw-signals-split/ because asking these questions is OT for that thread.
Speculation is OT for this thread

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.]

As you have been told ad nauseam, Shapiro delay is a GR effect, so it's already included when you do a GR solution. It's not there in E&M, so it has to be accounted for separately.

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.)

We're discussing this purported Shapiro delay effect. Don't raise other topics of discussion here. It's hijacking.

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?

Then don't post.

There are three things you can do in this thread: defend the proposal, ask questions to clarify the proposal, or post accepted physics to disprove the proposal. That's it. If you don't agree with the proposal but can't contradict it, you have nothing to discuss. Commentary along the lines of "I think it's real but it will be too small" is the worst combination. It means you reject mainstream physics but can't test or support your objection. If you can't do that, it should not be posted (that's spelled out in the guidelines for posting in speculations. You have no excuse for not being familiar with them)

[Robittybob1]

As you have been told ad nauseam, Shapiro delay is a GR effect, so it's already included when you do a GR solution. It's not there in E&M, so it has to be accounted for separately.

....

What was E&M an abbreviation for please? Was it energy and mass?

I'm a bit confused by what you say here. "Shapiro delay is a GR effect, so it's already included when you do a GR solution." Are you saying it is happening and is in the GR model and therefore in the GW150914 "chirp"?

 

I have been asking what arrangement of energy and mass is required to measure Shapiro time delay?

Edited March 18, 2016 by Robittybob1

[swansont]

What was E&M an abbreviation for please?

Electricity and Magnetism. Responsible for light/photons.

 

 

I'm a bit confused by what you say here. "Shapiro delay is a GR effect, so it's already included when you do a GR solution." Are you saying it is happening and is in the GR model and therefore in the GW150914 "chirp"?

Yes. As Mordred has said probably a dozen times already. (But not via the mechanism DanMP has proposed.)

 

 

I have been asking what arrangement of energy and mass is required to measure Shapiro time delay?

It's a gravitational time dilation effect. You need mass.

[Robittybob1]

 

Electricity and Magnetism. .....

 

It's a gravitational time dilation effect. You need mass.

EM ok Thanks.

 

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?

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?

...

@DanMP have you done the Force calculations on a 1kg test mass and the BH masses (M1 and M2) in those arrangements? If you were up there standing close to the binaries orbiting you would need to calculate whether G*m1/(r1^2) + G*m2/(r4^2) < G*m1/(r2^2) + G*m2/(r3^2) where r1 is the distance to M1 when it is closest and r4 is when M2 is furthest away on opposite side of the orbit and r2 and r3 are the side by side distances back to your position.

Edited March 19, 2016 by Robittybob1

[Robittybob1]

No the Shapiro delay and the chirp are two different things. A Shapiro delay will affect all frequencies and polarizations of the chirp equally.

 

The paper you posted uses the quadrupole spin 2 statistics but doesn't state differences in each polarization (correctly so).

 

" The chirp indicates that as gravitational waves are emitted, they carry energy away from the binary. The gravitational binding energy decreases, and the orbital frequency increases." See below paper on the chirp calculations in the pocket handbook section

 

The Shapiro delay would have the same influence upon each emitted wave.

 

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

@ Mordred - Where did you get this from? "A Shapiro delay will affect all frequencies and polarizations of the chirp equally."

No you obviously don't understand the Shapiro delay or the chirp.

 

The Shapiro delay is essentially the time dilation due to travelling through a gravity well.

 

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.

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?

....

 

See pages 6,7 and 8. Where you account for position of the two objects, they include the time components on page 8

 

...

What do you mean by "position"? Where would position be determined from?

 

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

[swansont]

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.

That "you fail to see" means nothing. Valid science does not require your stamp of approval.

 

If you don't understand anything about Shapiro time delay, you should be asking about it in another thread. Not here, because if you don't understand it, you can't defend the proposal or argue against it.

[Robittybob1]

That "you fail to see" means nothing. Valid science does not require your stamp of approval.

 

If you don't understand anything about Shapiro time delay, you should be asking about it in another thread. Not here, because if you don't understand it, you can't defend the proposal or argue against it.

I asked a question about mass as well, so could you explain that bit too please?

 

 

You say "You need mass." ... There is plenty of mass in the BBH. So where abouts do we need this mass please?

[swansont]

I asked a question about mass as well, so could you explain that bit too please?

 

 

You say "You need mass." ... There is plenty of mass in the BBH. So where abouts do we need this mass please?

The mass has to be near the trajectory of the EM signal. The closer it is, the larger the effect. Time dilation depends on how deep you are in a potential well. The Shapiro delay is the cumulative time dilation owing to the trajectory. Go deeper in the well and there is a larger delay.

 

This is why you see the effect with a pulsar. The signal gets delayed by varying amounts if it passes near a massive partner, and it modulates the signal.

[Mordred]

@ Mordred - Where did you get this from? "A Shapiro delay will affect all frequencies and polarizations of the chirp equally."

 

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?

 

 

What do you mean by "position"? Where would position be determined from?

 

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

Yes it affects all signals equally which is the same as I stated.

 

The constant velocity is describing systems that don't emit gravity waves. Not all objects in space will.

 

it's not the objects itself emitting the waves. Its the spacetime region surrounding the objects where the waves are generating.

 

The position of system orientation to the observer. This is why the equations on those pages have sine and cos functions.

 

Note though the metrics don't care where each BH is located the system it is specifically described as a SUM of mass. In other words the BINARY SYSTEM orientation.

 

An analogy is water surrounding a rock. Move the rock waves are generated.

Edited March 19, 2016 by Mordred

[swansont]

"A Shapiro delay will affect all frequencies and polarizations of the chirp equally."

 

 

Put another way, it's a gravitational time dilation effect. It affects all EM signals the same way. Just as with a kinematic time dilation effect.

[Robittybob1]

That "you fail to see" means nothing. Valid science does not require your stamp of approval.

 

If you don't understand anything about Shapiro time delay, you should be asking about it in another thread. Not here, because if you don't understand it, you can't defend the proposal or argue against it.

I thought we were saying that the GW had passed close to another star as it traveled toward the Earth. I just could not see how the wave produced within/by the binary would be gravitationally delayed by the masses that produced the wave in the first place.

For that would mean it was produced by each mass within the binary separately and I was persuaded that it was the combined mass of the system that produced the wave, a circularly polarized wave, but if that wave passed another star, BH or galaxy on it way through space then it might be Shapiro time delayed. You would have nothing to compare the delayed wave with, so no one could determine if it was delayed.

The mass has to be near the trajectory of the EM signal. The closer it is, the larger the effect. Time dilation depends on how deep you are in a potential well. The Shapiro delay is the cumulative time dilation owing to the trajectory. Go deeper in the well and there is a larger delay.

 

This is why you see the effect with a pulsar. The signal gets delayed by varying amounts if it passes near a massive partner, and it modulates the signal.

I can see how one member of a pulsar binary affects the pulsar signal, but my doubts were about the GW wave produced from the same pulsar binary, what effect would it have if it was eclipsed? Mordred seems to go for the GW being produced by the system and not by the individual masses #9

 

Note though the metrics don't care where each BH is located the system it is specifically described as a SUM of mass. In other words the BINARY SYSTEM orientation.

Edited March 22, 2016 by Robittybob1

[Mordred]

That is different than Dan's proposal. However same problem is that all frequencies and polarization would have the same delay.

 

Probably accounted for under redshift of the data.

 

Let's ask a question...

 

When you have two objects under each other's gravitational influence. Does not one affect the other and vise versa ?.

 

How can you possibly have one BH change acceleration without some degree in change of acceleration in the other BH?

 

You've studied enough orbits Did you forget the center of mass and barycenter aspects?

 

You take two equivelent mass objects in orbit the center of mass lies halfway between them. Change one mass both orbits are effected.

Edited March 22, 2016 by Mordred

[Robittybob1]

That is different than Dan's proposal. However same problem is that all frequencies and polarization would have the same delay.

 

Probably accounted for under redshift of the data.

 

Let's ask a question...

 

When you have two objects under each other's gravitational influence. Does not one affect the other and vise versa ?.

 

How can you possibly have one BH change acceleration without some degree in change of acceleration in the other BH?

 

You've studied enough orbits Did you forget the center of mass and barycenter aspects?

 

You take two equivelent mass objects in orbit the center of mass lies halfway between them. Change one mass both orbits are effected.

https://en.wikipedia.org/wiki/Shapiro_delay#Time_delay_due_to_light_traveling_around_a_single_mass

 

The time delay effect was first observed in 1964, by Irwin Shapiro. Shapiro proposed an observational test of his prediction: bounce radar beams off the surface of Venus and Mercury, and measure the round trip travel time. When the Earth, Sun, and Venus are most favorably aligned, Shapiro showed that the expected time delay, due to the presence of the Sun, of a radar signal traveling from the Earth to Venus and back, would be about 200 microseconds,[1] well within the limitations of 1960s era technology.

Could the same sort of thing happen to a GW passing another mass other than the ones that caused the wave? That was my question.

The Sun could slow the wave to one of the LIGO recorders but not the others, that could delay the wave by 100 microseconds (half of the two way delay). A delay as small as this would hardly be noticeable. The signal from GW150914 had a delay of 7 milliseconds which they used to determine the direction of space the signal came from. 7 millisecs is 7000 microseconds so an increase to 7100 microseconds would be noticed. They would then need to check if the wave could have passed the Sun on the way to the recorder if the Sun was in that general area as well.

 

They would affect each other's orbital characteristics but how would you relate that back to Shapiro time delay?

[Mordred]

No you wouldn't get that effect.

 

Do a little trigonometry, take two points place them day 1 million km apart. Then draw a line from each of those points over several billion km's. The angle between the two lines would be less than a degree, far less.

 

If the system was close by then possibly but the sheer distance would make any significant angle impossible.

 

Ever looked at a binary star system with a telescope? They appear to be almost on top of each other as a single star. The seperation angle is so miniscule that both light paths would suffer the same spacetime path around our sun. Or close enough to have immeasurable difference.

[Robittybob1]

No you wouldn't get that effect.

 

Do a little trigonometry, take two points place them day 1 million km apart. Then draw a line from each of those points over several billion km's. The angle between the two lines would be less than a degree, far less.

 

If the system was close by then possibly but the sheer distance would make any significant angle impossible.

 

Ever looked at a binary star system with a telescope? They appear to be almost on top of each other as a single star. The seperation angle is so miniscule that both light paths would suffer the same spacetime path around our sun. Or close enough to have immeasurable difference.

OK I agree. Even if the two LIGO recorders are 2000 km apart the path of the wave past the Sun, both fronts would have the same or nearly the same time delay such that the difference would not be noticed, an "immeasurable difference".

[Robittybob1]

I thought I understood Shapiro Time delay (STD) but I'm no longer certain. One article I read said once the light has been time delayed (slowed down) it doesn't ever regain its light speed after that.

So what happens when light is time delayed?

Could gravity be time delayed as well?

Could gravity waves (GW) be time delayed by the masses that produced them in the first place?

 

Which part of the chirp wave would be affected if the GW was time delayed

 

How much time delay would a 30 solar mass BH produce?

How much time delay would 2 * 30 solar mass binary BHs (BBH) produce? (As a ratio to the orbital separation.)

Is gravitational time delay the same as Shapiro time delay?

Any question, any insight on STD welcome.

 

[swansont]

I thought I understood Shapiro Time delay (STD) but I'm no longer certain. One article I read said once the light has been time delayed (slowed down) it doesn't ever regain its light speed after that.

The article is wrong, or your understanding of what it said is mistaken.

 

So what happens when light is time delayed?

The signal arrives later than one which is not delayed.

[Strange]

So what happens when light is time delayed?

Could gravity be time delayed as well?

 

Delay means "arrive later".

 

Could gravity waves (GW) be time delayed by the masses that produced them in the first place?

 

The delay is caused when light (or gravitational waves) pass a massive object. So, no.

 

Which part of the chirp wave would be affected if the GW was time delayed

 

All of it would be affected equally. If your bus was delayed, would you expect different parts of it to be delayed by different amounts?

 

How much time delay would a 30 solar mass BH produce?

How much time delay would 2 * 30 solar mass binary BHs (BBH) produce? (As a ratio to the orbital separation.)

 

It depends: https://en.wikipedia.org/wiki/Shapiro_delay#Calculating_time_delay

 

Is gravitational time delay the same as Shapiro time delay?

 

Shapiro delay is gravitational, so presumably yes.

[Robittybob1]

 

Delay means "arrive later".

 

 

The delay is caused when light (or gravitational waves) pass a massive object. So, no.

 

 

All of it would be affected equally. If your bus was delayed, would you expect different parts of it to be delayed by different amounts?

 

 

It depends: https://en.wikipedia.org/wiki/Shapiro_delay#Calculating_time_delay

 

 

Shapiro delay is gravitational, so presumably yes.

I've got a bit of study to do before I can check your answers. Sorry.

 

The article is wrong, or your understanding of what it said is mistaken.

 

 

The signal arrives later than one which is not delayed.

I'll come across it again and we'll check it out. I don't remember the source but the thought has stuck. I really wondered if what they said was right.