Speed of gravity
in [Relativity]
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From: Darwin123 on 2 Mar 2010 21:23 On Feb 28, 12:06 pm, Art <n...(a)zilch.com> wrote: > On Sun, 28 Feb 2010 06:55:06 -0800 (PST), Darwin123 > > <drosen0...(a)yahoo.com> wrote: > > Here is my conjecture on what you may have read concerning > >gravitational instability. > > If the speed of gravitational waves is a finite value, including > >c, all orbits are unstable. This is because the orbiting body emits > >gravitational waves. > > The effect on computed orbits is usually > disastrous because conservation of angular momentum is destroyed. That statement is not logical because a delay doesn't necessarily violate conservation of momentum. The gravitational field and associated gravimagnetic field can hold momentum, thereby maintaining the balance. In electrodynamics, there is a known delay of electromagnetic force. However, the delay doesn't violate conservation of momentum. The electromagnetic field holds both linear and angular momentum. There is a theorem showing that both energy and momentum is conserved in the case of charged particles interacting via their electrical and magnetic fields. However, some of the energy and momentum goes into electromagnetic waves. There are also near field effects where the electromagnetic field holds a substantial amount of energy and momentum. The case of general relativity (GR) is more complex. One can't precisely use the gravitational analogue to electromagnetic theory in GR. However, I have read that GR case is very similar with respect to the conservation laws. Both energy and momentum are conserved. However, some of the energy and momentum may end up in the form of gravitational waves.
From: glird on 2 Mar 2010 22:03 On Mar 2, 9:23 pm, Darwin123 <drosen0000(a)yahoo.com> wrote: > On Feb 28, 12:06 pm, Art <n...(a)zilch.com> wrote: > On Sun, 28 Feb 2010 06:55:06 -0800 (PST), Darwin123 wrote: > > > Here is my conjecture on what you may have read concerning > > > gravitational instability. > > > If the speed of gravitational waves is a finite value, including > > > c, all orbits are unstable. This is because the orbiting body emits > > > gravitational waves. Nothing emits gravitational waves! A g-field is a density gradient. It travels with the matter-unit of which it is a portion; the matter surrounding the spinning "nucleus" that caused it to form and still exist. If something causes the strength of that gradient to change, the CHANGE would propagate at c or less, but that, I think, is entirely different than an orbiting body emitting g waves. glird
From: Dono. on 2 Mar 2010 22:19 On Mar 2, 7:03 pm, glird <gl...(a)aol.com> wrote: > > > Nothing emits gravitational waves! A Imbecile: http://en.wikipedia.org/wiki/Gravitational_wave#Sources_of_gravitational_waves
From: BURT on 2 Mar 2010 23:22 On Mar 2, 6:23 pm, Darwin123 <drosen0...(a)yahoo.com> wrote: > On Feb 28, 12:06 pm, Art <n...(a)zilch.com> wrote:> On Sun, 28 Feb 2010 06:55:06 -0800 (PST), Darwin123 > > > <drosen0...(a)yahoo.com> wrote: > > > Here is my conjecture on what you may have read concerning > > >gravitational instability. > > > If the speed of gravitational waves is a finite value, including > > >c, all orbits are unstable. This is because the orbiting body emits > > >gravitational waves. > > > The effect on computed orbits is usually > > disastrous because conservation of angular momentum is destroyed. > > That statement is not logical because a delay doesn't > necessarily violate conservation of momentum. The gravitational field > and associated gravimagnetic field can hold momentum, thereby > maintaining the balance. > In electrodynamics, there is a known delay of electromagnetic > force. However, the delay doesn't violate conservation of momentum. > The electromagnetic field holds both linear and angular momentum. > There is a theorem showing that both energy and momentum is conserved > in the case of charged particles interacting via their electrical and > magnetic fields. However, some of the energy and momentum goes into > electromagnetic waves. There are also near field effects where the > electromagnetic field holds a substantial amount of energy and > momentum. > The case of general relativity (GR) is more complex. One can't > precisely use the gravitational analogue to electromagnetic theory in > GR. However, I have read that GR case is very similar with respect to > the conservation laws. Both energy and momentum are conserved. > However, some of the energy and momentum may end up in the form of > gravitational waves. God is creating gravity strength and is flowing it through space. Aether flows the gravity geometry of mass along with this gravity strength. Mitch Raemsch
From: Igor on 3 Mar 2010 10:44
On Mar 2, 5:06 pm, Koobee Wublee <koobee.wub...(a)gmail.com> wrote: > On Mar 1, 9:53 am, carlip-nos...(a)physics.ucdavis.edu wrote: > > > General relativity predicts that gravity propagates at the speed of > > light, in the sense that if you change the matter configuration in > > some finite region, the gravitational effects of that change don't > > reach distant regions until after the light-travel time to those > > regions. > > You can say the same thing for Newtonian gravity. <shrug> Uh, excuse me Mister Wublee, but that's not quite correct. In Newtonian gravity, propagation is assumed to be instantaneous. Only when finite light speed is considered do we arrive at the modifications involved in GR. > > I wouldn't say Einstein "assumed" this -- it was not put > > into the derivation of the field equations of general relativity, > > Yes, it is not possible to show gravitational effect propagates at a > certain speed just by examining the field equations. <shrug> Excuse me again, but that's not quite true, either. Gravitational waves are easily shown to propagate at c. And these are derived from nothing but the field equations in the weak field limit. Now who's shrugging? > > but is, rather, a conclusion. > > Conclusion? You mean by a unanimous vote just like our congressmen > unanimously vote for their salary increase every single year while the > general public experience great hardship in this dire economy. > <shrug> Many people shrug when they have no clue about what is going on around them. Et tu, Wublee? |