What is the speed of gravity?

[Jonathan Ainsley Bain]

one of the aspects that is relevant here is the relative motion of the two sources and the time dilation produced by that motion. This also serves to counteract the issue you are discussing.

Not in the slightest, old chap!
Any slowing down of time has the opposite effect.
You need to speed up time to get the gravity to arrive more rapidly.
But doing either slower or faster time would violate THE basic premise of relativity that the speed of light be constant.

In the case of Alpha Centauri, the effects of Special Relativity are weaker than General Relativity by a factor of 2 in a million.

In the case of Mercury, Special Relativity overpowers General Relativity.
SR results in 40m per orbit spiral inwards here, and GR results in 2km spiral outwards.

In the case of the moon, its also dominated by GR such that the moon would spiral outwards
by 400m per orbit, which results in the virtually impossible age of the moon of less than 70 000 years.

You are so full of assumptions dear fellow!
Tally-ho!

 

[Polymath257]

Moreover its not the same article anyways.
The algorithm has been finely tuned so that orbits are calculated to a matter of millimeters
with all the applied formulae of relativity in effect.

The orbit of Mercury to within 0.2m over 20 orbits is precision.
See here :Relativity and the orbit of Mercury

Whereas your comments are mere words typed in a forum.


Perhaps you better jump to the full article released a few days ago:
www.flight-light-and-spin.com/simulator/relativity-orbit-solar-system.htm

I am still waiting for your algorithm which you claimed to have written.
And that was more than a year ago.

Well, I read your 'Sum Theory' article. You showed much of the lack of understanding most amateurs do in such matters. For example, in a exactly paired binary system, you state that the relative velocity is constant. That is false in a general relativistic setting (which is required here). The reason is that the spacetime metric for such a scenario has off-diagonal components representing the fact that things *are* changing in time. Even in a special relativistic setting, the relative velocity is not constant because circular motion is accelerated motion! The point is that the frame of reference where the binary couple is fixed is not an inertial frame. That carries over into the general relativistic formulation. And you seem to be completely unaware of that fact. In fact, you repeat the claim of constant velocity.

Next, your use of the velocity sum formula in special relativity is in error. What you need here is the relativistic correction to F=ma, and NOT the velocity sum formula if you want to analyze the contributions of the acceleration to the velocity. So, that aspect of your account is also in error.

Next, you gave nothing to show what you are using for your force law. If it is the simple inverse square law, then you are in error once again. That is simply the Newtonian approximation. Even if used with the *correct* special relativistic force law (which you don't have), it would not take into account the s from general relativity. In fact, it was this very problem that lead Einstein to GR.

Finally, you show no awareness at all of what GR actually says, no mention of spacetime metrics, no proposed calculation of Christoffel symbols or the resulting geodesics. You don't show how to find the appropriate formulas to use. All of this would be required to do a *correct* treatment of the binary system in GR.

In the end, you have an 'algorithm', in other words a computer program, but you haven't actually justified that program in any way. You seem to be unaware of the basics of the theories you are criticizing and whatever you actually programmed is thereby irrelevant.

 

[Polymath257]

I must have pushed the wrong button.

Love it. No idea what you're talking about. I guess that's the point.

Not you.

 

[sayak83]

The profound detail of your analysis!
The ease with which you sum up the formulae!
The originality in your proof!
ah
Albert would be proud.

Thanks. He would certainly be.

 

[sayak83]

Oh, I'm just interested in what different scientists have to say. The variety of conclusions is fun. I'm guessing that in the next decade some scientist will prove the LIGO findings wrong, or at least incomplete. I'll ready the water balloons.

Unlikely.

 

[Willamena]

I suspect that the speed of gravity is roughly equivalent to the airspeed velocity of an unladen swallow.

 

[sayak83]

Not in the slightest, old chap!
Any slowing down of time has the opposite effect.
You need to speed up time to get the gravity to arrive more rapidly.
But doing either slower or faster time would violate THE basic premise of relativity that the speed of light be constant.

In the case of Alpha Centauri, the effects of Special Relativity are weaker than General Relativity by a factor of 2 in a million.

In the case of Mercury, Special Relativity overpowers General Relativity.
SR results in 40m per orbit spiral inwards here, and GR results in 2km spiral outwards.

In the case of the moon, its also dominated by GR such that the moon would spiral outwards
by 400m per orbit, which results in the virtually impossible age of the moon of less than 70 000 years.

You are so full of assumptions dear fellow!
Tally-ho!

You don't know a thing about GR do you?

 

[sayak83]

Oh, I'm just interested in what different scientists have to say. The variety of conclusions is fun. I'm guessing that in the next decade some scientist will prove the LIGO findings wrong, or at least incomplete. I'll ready the water balloons.

An experiment that gets the Nobel is usually so well validated, that its not overturned. Not happened ever so far.

Gravitational waves, explained

 

[sayak83]

Gadzooks! Time moves so fast. Er, I mean gravity. Er, I mean...

How speed of gravity was determined.

https://phys.org/news/2017-11-physicists-rapid-bounding-gravity.html

Just two days later (and after the physicists mentioned above wrote their paper), another paper was published in The Astrophysical Journal Letters by the LIGO and Virgo collaborations, whose authors are affiliated with nearly 200 institutions around the world. By using data from the gravitational waves emitted by a binary neutron star merger detected in August, they were able to constrain the difference between the speed of gravity and the speed of light to between -3 x 10^-15 and 7 x 10^-16 times the speed of light.

The reason for the huge leap in precision is that the neutron star event did not emit only gravitational waves, but also electromagnetic radiation in the form of gamma rays. The simultaneous emission of both gravitational waves and light from the same source allowed the scientists to set bounds on the speed of gravity that is many orders of magnitude more stringent that what could be set using gravitational wave signal alone.

When a source emits both gravitational waves and light, scientists can measure the difference (if any) in the arrival times of the two different types of signals at a single detector. In the AJL paper, the scientists measured an arrival delay of just a few seconds between signals that traveled a distance of more than one hundred million light years. Such a small delay across this distance is considered virtually nothing.

"Many alternative theories of gravity, including some that have been invoked to explain the accelerated expansion of the Universe, predict that the speed of gravity is different from the speed of light," Cornish said. "Several of those theories have now been ruled out, thereby restricting the ways in which Einstein's theory can sensibly be modified, and making dark energy a more likely explanation accelerated expansion."

 

[lostwanderingsoul]

Gravity is a force. It can cause objects to accelerate toward each other but gravity does not have a speed. you might as well say what is the speed of a 200 horsepower engine. The engine can cause the car to move but the engine itself does not have a speed.

 

[Aupmanyav]

I must have pushed the wrong button.

Had you not pushed the wrong button we would not have had the explanations and counter-explanations. It is good to push the wrong button once in a while.

 

[tayla]

If gravity does travel at 'the speed of light', then how would this alter
the orbits of the planets?

www.flight-light-and-spin.com/gravity/speed-of-gravity.htm

Warning: the linked web page was blocked by my virus protection software.

 

[sayak83]

Gravity is a force. It can cause objects to accelerate toward each other but gravity does not have a speed. you might as well say what is the speed of a 200 horsepower engine. The engine can cause the car to move but the engine itself does not have a speed.

Please read the posts above.

 

[Polymath257]

Thanks I'll have to look that up.

As I apply gravity at the velocity of light to the Alpha Centauri system, the
result would be an outwards movement due to the delay.
The exact outwards movement is 1.4million km per orbit.
Here are the precise computations: Relativity and the orbits of Alpha Centauri

I notice those are not actually computations, but the results of a computer program where you give no details concerning how things are actually computed. For example, what approximation method do you use for the differential equations? Runge-Kutta, perhaps? Or just Euler update? What specific DE do you use in each case? In particular, what basic formula do you use for your updates in the GR case?

I outline the principle as to why gravity must be
either instant or many times the velocity of light quite clearly here: Instant Gravity Proof
Its quite easy to understand.

Easy to understand and completely wrong. In essence, you are looking at one component of a 10 component system of equations. By doing so, you neglect terms that are significant for your analysis, making the whole argument flawed.

It is even flawed in E&M (the Coulomb law is an approximation for static systems that needs to be corrected for moving sources). GR goes a step or two further in the complexity, having a tensor to update instead of a vector. But the basic issue is that the simple 'direction of the object in the past' formulation is flawed.

 

[WalterTrull]

How speed of gravity was determined.

https://phys.org/news/2017-11-physicists-rapid-bounding-gravity.html

Just two days later (and after the physicists mentioned above wrote their paper), another paper was published in The Astrophysical Journal Letters by the LIGO and Virgo collaborations, whose authors are affiliated with nearly 200 institutions around the world. By using data from the gravitational waves emitted by a binary neutron star merger detected in August, they were able to constrain the difference between the speed of gravity and the speed of light to between -3 x 10^-15 and 7 x 10^-16 times the speed of light.

The reason for the huge leap in precision is that the neutron star event did not emit only gravitational waves, but also electromagnetic radiation in the form of gamma rays. The simultaneous emission of both gravitational waves and light from the same source allowed the scientists to set bounds on the speed of gravity that is many orders of magnitude more stringent that what could be set using gravitational wave signal alone.

When a source emits both gravitational waves and light, scientists can measure the difference (if any) in the arrival times of the two different types of signals at a single detector. In the AJL paper, the scientists measured an arrival delay of just a few seconds between signals that traveled a distance of more than one hundred million light years. Such a small delay across this distance is considered virtually nothing.

"Many alternative theories of gravity, including some that have been invoked to explain the accelerated expansion of the Universe, predict that the speed of gravity is different from the speed of light," Cornish said. "Several of those theories have now been ruled out, thereby restricting the ways in which Einstein's theory can sensibly be modified, and making dark energy a more likely explanation accelerated expansion."

Holy bonkers! I might be starting to understand this stuff (well, in general terms anyway) Thanks for the link. ( Although, I'm not sure about the refrigerator foods.)

 

[Rough Beast Sloucher]

Warning: the linked web page was blocked by my virus protection software.

Same here.

 

[Polymath257]

If you want an *actual* analysis of the two body problem in general relativity, look at the paper

https://arxiv.org/pdf/1312.3505.pdf

or maybe

https://arxiv.org/pdf/1312.2503.pdf

At least these papers show an awareness of the mathematical subtleties involved in solving the two body problem in GR.

Good luck!

 

[Jonathan Ainsley Bain]

not actually computations, but the results of a computer program where you give no details concerning how things are actually computed.

You certainly did not read the full article (properly if at all) which gives all the details.
It even explains minute aspects of error margins for Newtonian calculations.
(perhaps you are trying to get me to copy-paste my code so you can pass it off as your own?)

The basic concept of gravity travelling at the velocity of light was a result of the field equations,
and not something in addition to it, as the quotes show in the starting post.


Consider this:

If gravity and light travel at the same velocity under the same laws of physics then they must both follow the same trajectory.
So if your interpretation of the Relativity laws resulted in it appearing "as if" gravity had the same origin under Relativity as it would under Newton,
then light would also appear to be originating across the midpoint and it would thus be impossible to measure
the velocity of light by observing the moon's of Jupiter.

So if gravity follows a different path to light then it would be wrong to consider them
as having the same velocity, and operating under the same laws.

The logical errors you and almost every other theorist in the history of science and philosophy make
is to think that quoting esoteric jargon is the same as understanding. Its not.

You need to start by programming "triple orbit software" (or "multi-orbit software") on a purely Newtonian level.
You probably would like to scoff at this; thinking it is beneath you,
but I still see no evidence that you or anyone else fully understands how to do this.
n-body Newtonian gravity is certainly simpler than Relativity,
and yet Hawking clearly states:

(Brief History of Time)

So perhaps, see if you can jargonize your way out of the next basic problem, which no doubt you feel is no problem.
I am reminded of this by the other paper listed on this thread.

If a photon is moving away or towards my nose at the velocity of light,
then under the principles of Relativity, my nose is moving at a velocity of C in respect to the photon.

Thus, the laws of Special Relativity would result in my nose acquiring infinite mass as my nose
is relatively moving at the velocity of light when measured against the photon.

Seeing as though my nose clearly would not have infinite mass relative to the photon
it follows that special relativity simply is wrong.

Saying 'you do not understand' over and over again, is not an explanation,
but an attempt to assert your ego, and nothing more.
This is the norm of atheist academia, as it always has been for countless millennia.

 

[Jonathan Ainsley Bain]

You don't know a thing about GR do you?

I know enough logic to know that its sophistry.
Can you tell the difference between logic and idol-worship?

Warning: the linked web page was blocked by my virus protection software.

which virus protection software is that?
Its quite likely malware itself if it cannot properly evaluate what is harmless.
Just because it says 'virus protection', does not make it so.

 

[tayla]

which virus protection software is that?

Norton