Stephen P. King (stephenk1@home.com)
Sat, 10 Jul 1999 15:50:46 -0400
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!
:-)
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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