🚀 go-pugleaf

In article <1992Sep29.065640.18839@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes:

>So my conjecture is that a binary star gives the optimal experimental
>conditions for measuring the velocity of gravity.  (If this weren't
>Usenet I'd have to call this a question, not having paid my dues.
>Usenet doesn't have dues, a nice feature, that.)
>
>Anyone care to express strong opinions either way on this question?

I'm really busy with my homework so I'll keep this short.  It's
awfully hard to measure the velocity of gravitational radiation
directly.  Trying to measure it using a binary star is somewhat
analogous to trying to measure the speed of light by looking at
a hydrogen atom (which is bound electromagnetically).  It's NOT
a matter of one star "seeing" a delayed image of the other!  This is
*not* what happens [as has occaisionally been explained here on
sci.physics - time for a FAQ on this??]

However, one can calculate perturbatively the effects
due to GR in a binary star system, including energy loss due to
gravitational radiation.  There is a double pulsar (or is it a
pulsar/netron star pair?) which has been carefully tracked for many
years and provides a good verification of these calculations.  This
offers some of the best evidence we have for GR in the "rapidly moving
source" regime, hence indirect evidence that gravitational radiation
does what GR says it does.