What is the speed of gravity?

[Jonathan Ainsley Bain]

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

 

[Polymath257]

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

Not this again. Your understanding of what GR says is faulty. The speed of gravity is the speed of light *and* the observed reaction allows for stable orbits, except for small changes in the direction of the parahelion.

 

[David T]

Not this again. Your understanding of what GR says is faulty. The speed of gravity is the speed of light *and* the observed reaction allows for stable orbits, except for small changes in the direction of the parahelion.

A bit like a tsunami actually. Standing on shore it will appear one way, in the middle of the ocean at depth it won't be noticed. There actually is no shoreness, in the cosmos since everything is of the same substance energy or "fire"as Heraclitus said 2600 years ago..weird that he understood that.. lots of theoretical shores are created daily though!

 

[WalterTrull]

Well... according to Brian Fraser in Beyond Einstein, gravity is much faster than light. I'm not sure I follow (actually I'm sure I don't follow) non-local math, but it's interesting.

 

[Polymath257]

Well... according to Brian Fraser in Beyond Einstein, gravity is much faster than light. I'm not sure I follow (actually I'm sure I don't follow) non-local math, but it's interesting.

I follow it. It is just wrong. Both gravity and electromagnetism travel at the speed of light. Neither is non-local.

And the EPR paradox does NOT show faster-than-light causality. That is a misunderstanding of the quantum physics. QM is a *local* but non-causal theory.

 

[sayak83]

Everything polymath is saying is correct.

 

[Revoltingest]

Everything polymath is saying is correct.

......and entirely inaccessible to us lesser folk.
But he comports far better with scientific consensus.
And he looks the part of a big brained professor....

 

[sayak83]

......and entirely inaccessible to us lesser folk.
But he comports far better with consensus.
And he looks the part of a big brained professor....

These are advanced physics for a reason. Its not difficult, but it requires a lot of learning to get to the point where one can understand.

 

[Altfish]

Gravity isn't a speed, it doesn't have a speed?
Gravity is a force and is measured as an acceleration

Speed is measured in miles/hour or km/sec, etc.
Acceleration is the rate of change of speed with time and is measured in miles / hour*hour (That should be hours squared). the acceleration of gravity on the surface of the earth at sea level is 9.8 m/s2.

 

[sayak83]

Gravity isn't a speed, it doesn't have a speed?
Gravity is a force and is measured as an acceleration

Speed is measured in miles/hour or km/sec, etc.
Acceleration is the rate of change of speed with time and is measured in miles / hour*hour (That should be hours squared). the acceleration of gravity on the surface of the earth at sea level is 9.8 m/s2.

Gravitational waves propagate at the speed of light. Thus, if Sun were to suddenly vanish, the earth would be flung out of orbit after 8 minutes, the time it takes the associated gravitational field change to reach earth.

 

[Aupmanyav]

Everything polymath is saying is correct.

I find Polymath very humble for all his knowledge. If I knew that much, I would be strutting around lecturing people.

 

[WalterTrull]

Gravitational waves propagate at the speed of light. Thus, if Sun were to suddenly vanish, the earth would be flung out of orbit after 8 minutes, the time it takes the associated gravitational field change to reach earth

So you disagree with this quote from the above Frasier paper.
"The most obvious and incontrovertible experimental evidence for an extremely high speed of gravity is that gravity has no aberration (see figure below). Gravity from an object always coincides with that object’s position. If the object moves, there is no gravity still on its way from the “retarded position”, as there would be from a light or sound source. Evidence from the motions of celestial bodies, from radar ranging, and from a binary pulsar lead to the conclusion that the speed of gravity is at least 20 billion times (20 x 109) faster than the speed of light."

 

[Altfish]

Gravitational waves propagate at the speed of light. Thus, if Sun were to suddenly vanish, the earth would be flung out of orbit after 8 minutes, the time it takes the associated gravitational field change to reach earth.

But the OP said Gravity, not Gravitational Waves - there is a big difference.

 

[Polymath257]

So you disagree with this quote from the above Frasier paper.
"The most obvious and incontrovertible experimental evidence for an extremely high speed of gravity is that gravity has no aberration (see figure below). Gravity from an object always coincides with that object’s position. If the object moves, there is no gravity still on its way from the “retarded position”, as there would be from a light or sound source. Evidence from the motions of celestial bodies, from radar ranging, and from a binary pulsar lead to the conclusion that the speed of gravity is at least 20 billion times (20 x 109) faster than the speed of light."

Yes, I disagree. That is a wrong understanding of what GR says. It is also a misunderstanding of what E&M predicts.

Changes in the gravitational field travel at the speed of light. But, just like with electromagnetism, there is a 'correction' in the specific force law that makes the *approximation* that gravity comes from the object's position a very good one. This comes about because of relativistic effects.

For the E&M force law, this can be seen explicitly in the Feynman lectures when he introduces the E&M force. For GR, it comes from an integral form for the 'force' on an object.

 

[David T]

Well... according to Brian Fraser in Beyond Einstein, gravity is much faster than light. I'm not sure I follow (actually I'm sure I don't follow) non-local math, but it's interesting.

Brian also "believes" in one dimensional strings, that are tiny harps the generate reality and that there are at least 12 various dimensions.

Being a left handed Aquarius and my dimension sign is a sine wave I know Brian is nutty! I mean here we have empirical evidence of string theory wrong simply because a left handed Aquarian is nuts by all evidence saying string theory is nutty.

I should , by all scientific evidence be a string theorist and using it as proof the lock ness monster is real. The lock ness monster is not real it's Scottish. Big foot is absolutely real because I live in the northwest, it exists inter-dimensionally in the dimension Taurus.

Ps
I love this site!!!!
PSS
I actually did a rant on Brian green, Brian Fraser has a totally different take. I found my rant too funny to delete, and yet relevant because we can see in a whole bunch of different ways, each with some truth and a whole lot of confusion.

 

[columbus]

Gravitational waves propagate at the speed of light.

I prefer to believe differently.

Prove this claim to my satisfaction
or I will know that it's just a theory like evilution. You atheists will claim anything, I know what you're like.....


Tom

 

[David T]

Everything polymath is saying is correct.

Stating the self evident is not making a statement!!! Although there is no such thing as a field of polymath that I could find. WTH!! It appears to be a term that people with ADHD apply to themselves and to others who suffer from the same mental disorder!!! I always hated being called ADHD, which reminds me did you see the news today?

 

[WalterTrull]

Yes, I disagree. That is a wrong understanding of what GR says. It is also a misunderstanding of what E&M predicts.

Changes in the gravitational field travel at the speed of light. But, just like with electromagnetism, there is a 'correction' in the specific force law that makes the *approximation* that gravity comes from the object's position a very good one. This comes about because of relativistic effects.

For the E&M force law, this can be seen explicitly in the Feynman lectures when he introduces the E&M force. For GR, it comes from an integral form for the 'force' on an object.

It's fascinating how different physicists and mathematicians, given the same numbers, have differing interpretations of their meanings. Kinda fun. Never-the-less, thanks for turning me on to the Feynman lectures. I've got a lot of watching to do. I wish he didn't pace so much.

 

[Skwim]

So you disagree with this quote from the above Frasier paper.
"The most obvious and incontrovertible experimental evidence for an extremely high speed of gravity is that gravity has no aberration (see figure below). Gravity from an object always coincides with that object’s position. If the object moves, there is no gravity still on its way from the “retarded position”, as there would be from a light or sound source. Evidence from the motions of celestial bodies, from radar ranging, and from a binary pulsar lead to the conclusion that the speed of gravity is at least 20 billion times (20 x 109) faster than the speed of light."

Well, Frasier's paper, written in 2015, does predate the establishment of gravitational waves in 2017, in which it was discovered that "gravity moves at 299,792,458 metres per second, a rate we can just call c." So there's no reason to pay any attention to his paper. It's outdated and his conclusion worthless.
source

.

 

[sayak83]

So you disagree with this quote from the above Frasier paper.
"The most obvious and incontrovertible experimental evidence for an extremely high speed of gravity is that gravity has no aberration (see figure below). Gravity from an object always coincides with that object’s position. If the object moves, there is no gravity still on its way from the “retarded position”, as there would be from a light or sound source. Evidence from the motions of celestial bodies, from radar ranging, and from a binary pulsar lead to the conclusion that the speed of gravity is at least 20 billion times (20 x 109) faster than the speed of light."

The paper is complete rubbish.