[time 440] Re: [time 439] Re: [time 437] Dissipation


Matti Pitkanen (matpitka@pcu.helsinki.fi)
Sat, 10 Jul 1999 09:16:46 +0300 (EET DST)


On Sat, 10 Jul 1999, Stephen P. King wrote:

> Dear Matti and Bill,
>
> Perhaps the situation involving the decay in the orbit of binary
pulsars could
> help us in this discussion. The decay, I think, is attributed to the
loss of mass
> via gravity wave emission, but such gravity waves have not been
detected. BTW, it
> is good to be back up, my system was down, and it is great to hear from you Bill!
> :-)
>
Yes. This could be regarded as dissipation by graviton emission.

Best,
Matti
 
> Kindest regards,
>
> Stephen
>
> Matti Pitkanen wrote:
>
> > On Wed, 7 Jul 1999 WDEshleman@aol.com wrote:
> >
> > >
> > > > On Wed, 7 Jul 1999 WDEshleman@aol.com wrote:
> > > >
> > > > > Time Group,
> > > > >
> > > > > This, my first post, was inspired by the discussion of "dissipation". I
> > > > > enjoyed reading a great many posts after being away from my computer for
> > > a
> > > >
> > > > > time.
> > > > >
> > > > > My question is: Since Einstein tells us that all of the orbits around
> > > our
> > > >
> > > > > Sun loose about 28 kilometers (6*pi*G*M/c^2) of orbit per orbit due to
> > > GR,
> > > >
> > > > > then could this loss of length be interpreted as "dissipation" of
> > > orbital
> > > > > angular momentum.
> > > >
> > > > I am not sure what you mean with the effect the loss of
> > > > orbit... Mass point in Schwartscildt metric has stationary orbit. (Mati)
> > > >
> > >
> > > Mati,
> > >
> > > The loss to which I refer causes Mercury's perihelion to advance, but is
> > > present in all of the orbits around our Sun. I don't fully grasp why the
> > > entire orbit does not decay except that it is relativistic and makes the
> > > orbit itself orbit. Thus my question.
> >
> > OK. I think that the orbit does not shrink. One can say the the
> > approximately ellipse shaped orbit rotates. Therefore dissipation
> > is not in question: for instance, one can assign conserved energy
> > and angular momentum to the orbit in the approximation that motion occurs
> > in spherically symmetric stationary metric.
> >
> > I thought that the dissipation you were referring to might be from
> > gravitational radiation and indeed cause gradual decrease of the orbit
> > radius but this effect must be extremely small.
> >
> > >
> > > Calculations have indicated to me that near a black hole, the advance can be
> > > the entire orbit.
> >
> > Best,
> > MP
> > >
> > > Sincerely,
> > >
> > > Bill Eshleman
> > > http://members.tripod.com/EshlemanW/
> > >
>
>



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