[Pvfcadbh]

Does gravity propagate at the speed of light (ie gravity is electrodynamic)
or is gravity propagated instantaneously ?

[provigil]

It is assumed that it propagates at the speed of light, but proof is yet forthcoming.

But I guess we'll be getting your spin on things soon.

[Pvfcadbh]

gravity is electrodynamic, IMO

see Gerber's theory of gravity
https://sites.google.com/site/testso...English/gerber

he believes gravity is an attraction
the effect is not immediately imposed on, because the conditional process starts from the attracting mass and needs time in order to proceed to the attracted mass. Of course, the same kind of progression also occurs from the attracted to the attracting mass... and yet when he mathematically analyses the precession of Mercury
the gravitational interaction has the constant speed (of light) mmmh

[RogHammon]

I have often wondered what would happen if the sun was `magically' removed somehow- would the earth continue to orbit around a now nonexistant sun for 8 minutes before starting off in a straight line- or would it immediately head off

the first seems to be a bit strange- why would it continue to circle a non existent sun, but the second would imply faster than light communication would be possible (if we could generate artificial gravity that is) which would open up a whole new can of worms

[unsamiSlini]

According to GR gravity propagates at "c"
So if the Sun was magically "removed", it would take 8.25 minutes for the warpage that the Sun was responsible for, to dissipate leaving the Earth to fly of at a tangent.

[Pvfcadbh]

I have often wondered what would happen if the sun was `magically' removed somehow- would the earth continue to orbit around a now nonexistant sun for 8 minutes before starting off in a straight line- or would it immediately head off In my view, the Earth is driven around and in, an electromagnetic bubble vortex which is generated by the Sun, and spins around the Sun

If the Sun was magically removed.... it could take ages before this vortex became chaotic... so the Earth would continue onward in its spiral for a considerable length of time... ie much longer than 8 minutes

Shall we ask the Vogons to conduct an experiment ?

[CuittisIL]

Does gravity propagate at the speed of light (ie gravity is electrodynamic)
or is gravity propagated instantaneously ?

The speed of gravity has been measured for the first time. The landmark experiment shows that it travels at the speed of light, meaning that Einstein's general theory of relativity has passed another test with flying colours.

Ed Fomalont of the National Radio Astronomy Observatory in Charlottesville, Virginia, and Sergei Kopeikin of the University of Missouri in Columbia made the measurement, with the help of the planet Jupiter.

"We became the first two people to know the speed of gravity, one of the fundamental constants of nature," the scientists say, in an article in New Scientist print edition. One important consequence of the result is that it places constraints on theories of "brane worlds", which suggest the Universe has more spatial dimensions than the familiar three.

John Baez, a physicist from the University of California at Riverside, comments: "Einstein wins yet again." He adds that any other result would have come as a shock.

Isaac Newton thought the influence of gravity was instantaneous, but Einstein assumed it travelled at the speed of light and built this into his 1915 general theory of relativity.

Light-speed gravity means that if the Sun suddenly disappeared from the centre of the Solar System, the Earth would remain in orbit for about 8.3 minutes - the time it takes light to travel from the Sun to the Earth. Then, suddenly feeling no gravity, Earth would shoot off into space in a straight line.


http://www.newscientist.com/article/...-revealed.html

[RogHammon]

weird concept isnt it, an orbit continuing on as if the other body was still there when it wasnt for that time that it takes light to traverse the distance

other planets would continue to orbit for much longer for the further out ones obviously

Imagine sitting in a spaceship high above the solar plane and watching it happen
I am having some problems with visualising what happens- assuming the sun magically goes, then I am seeing the inner planets already shooting off in a straight line, while the outer ones continue to orbit for much longer

its a bit of a mind bender

[CtEkM8Vq]

I am having some problems with visualising what happens- assuming the sun magically goes, then I am seeing the inner planets already shooting off in a straight line, while the outer ones continue to orbit for much longer

its a bit of a mind bender Yep. Tricky one. What you see happen would also depend on how high above the solar plane you are too.

[RogHammon]

Im assuming to be high enough to be able to see it all at a glance so to speak- say the width of the entire system above it as a minimum

[CtEkM8Vq]

I'm thinking that if you were the distance of Jupiter away, you would begin to see the inner planets leave orbit while you could still see the sun as it's non-existence has not reached you yet, though perhaps that is balanced out by the light coming from the inner planets also taking time to reach you.

[unsamiSlini]

In my view, the Earth is driven around and in, an electromagnetic bubble vortex which is generated by the Sun, and spins around the Sun

If the Sun was magically removed.... it could take ages before this vortex became chaotic... so the Earth would continue onward in its spiral for a considerable length of time... ie much longer than 8 minutes

Shall we ask the Vogons to conduct an experiment ?

Interesting scenario as to what happens Zarkov.
But do you have any observational/experimental evidence to support such an hypothesis?
GR has been shown to describe how space/time acts in the presence of mass by many means now, probably one of the most important being GP-B.

[RogHammon]

Interesting scenario as to what happens Zarkov.
But do you have any observational/experimental evidence to support such an hypothesis?
GR has been shown to describe how space/time acts in the presence of mass by many means now, probably one of the most important being GP-B.

you been smokin the funny stuff BC???



asking zarky for evidence and stuff????


;-)

[unsamiSlini]

you been smokin the funny stuff BC???



asking zarky for evidence and stuff????


;-)

Just trying to be the usual nice reasonable astute bloke that I have become known for.... :-)

[provigil]

In my view, the Earth is driven around and in, an electromagnetic bubble vortex which is generated by the Sun, and spins around the Sun

Indeed. That's the thing about people, and views, is that there are just so many of them.

[provigil]

I'm thinking that if you were the distance of Jupiter away, you would begin to see the inner planets leave orbit while you could still see the sun as it's non-existence has not reached you yet, though perhaps that is balanced out by the light coming from the inner planets also taking time to reach you.

You're overthinking things.

While the inner planets would have started to be affected by the lack of sun before you noticed the sun wasn't there, you wouldn't notice the inner planets were acting strange until well after you were aware they should be.

[Pvfcadbh]

How fast does a field collapse ??
That is the real question

It seems to me, a field is generated from the source
If the source is removed, the field must collapse from that point (source) outwards... which means that if there is no support for the outlying field, the whole must collapse instantaneously.

IMO, gravity is the resultant of the field generated by the Sun interacting with the field of the Earth

so I am no wiser re the removal of the Sun !!!

Gravity on earth might suffer
and solar gravity might become chaotic

damn

[AdobeCreativeSuite]

Fields do not collapse instantaneously. This is not only an absolute requirement for physics as we know it it is something we can observe and test.

If you could show any evidence for a field collapsing instantaneously you would get your Nobel prize, change all of physics as we know it, allow FTL communication and a whole raft of other things.

However all the very real evidence we have is that fields do not collapse instantaneously.

[Pvfcadbh]

fields do not collapse instantaneously. Great

so gravity propagates at the speed of light.

[masterso]

Great

so gravity propagates at the speed of light.

well changes in gravitational potential propagate at the speed of light