Re: Sol-like system discovered...SETI new directions?

From: Mike Lorrey (mlorrey@yahoo.com)
Date: Fri Jul 11 2003 - 17:01:56 MDT

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    --- "Robert J. Bradbury" <bradbury@aeiveos.com> wrote:
    >
    > On Thu, 10 Jul 2003 ABlainey@aol.com wrote:
    >
    > > This is also my view , that gravity being instantanious gives an
    > > unbeatable method of information transfer. That is of course
    > > depending on the propgation speed. Everything I have read thus
    > > far states that the propogation is
    > > istantanious.
    >
    > Hmmmmm.... A google on "speed of gravity waves" yields:
    >
    > http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980905b.html
    > http://physics.about.com/library/weekly/aa011503a.htm
    > http://www.nature.com/nsu/030106/030106-8.html
    >
    > to which there appears to be an upstart challenge:
    >
    >
    http://www.lbl.gov/Science-Articles/Archive/Phys-speed-of-gravity.html
    >
    > So I would say that the balance of the conventional wisdom
    > is that gravity propagates at the speed-of-light.
    >
    > It is also true that to get gravity waves one has to manipulate
    > *very*
    > large masses. That is *very* expensive relative to the manipulation
    > of photons (which effectively have very low masses [based on E =
    > mc^2]).

    Well, the frame dragging phenomenon found in galactic arm structures is
    certainly an indication that gravity propagates at speed of light or
    thereabouts. On a different note, keep in mind that phenomena like
    supernova would not form black holes as they do if gravity did not
    travel in wave fronts at a finite velocity. If gravity propagated
    instantaneously, then massive stars would just magically turn into
    black holes without all the messy explosive effects.

    =====
    Mike Lorrey
    "Live Free or Die, Death is not the Worst of Evils."
                                                        - Gen. John Stark
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