Re: Speed of Gravity

[This was sent to traveller-request, so I forwarded it on to the
distribution list.  Watch your To: address! -- James]

As far as I can remember, current theories call for a charge carrier
particle for all four forces.  The carriers of electromagnetism (the
photon), the strong nuclear force (the pion) and the weak nuclear
force (the intermediate weak boson) have been found.  All have zero
rest mass and all have a set velocity of c, 2.998x10^8 m/s.  The
reason that they are affected by gravity is that they have a mass
due to their speed -- zero mass and infinite (relativistic) speed
yields any number for relativistic mass you want... ^_^  Since they
have mass, black holes can haul them back, and they end up orbiting
inside the event horizon if they enter it.

No one has found the fourth, the 'graviton', because it would be very
difficult to build a graviton detector.  (Can you think of a
substance that isn't affected by gravity?)  However, it is also
postulated to have zero rest mass and a velocity of c.  I believe
that it is not supposed to be affected by itself (i.e. gravitons
can escape the effects of black holes), perhaps because it can't
make sense any other way.  I'm not quite sure, but I assume that
since black holes are postulated to have an effect outside their
event horizon, gravitons are not affected by gravity.  (Perhaps they
have no mass?  Hmmm.)

Responding to Adrian Hurt's second 'stupid' question, as he calls
it, I believe that black globes block the electromagnetic force
exclusively.  All electromagnetic radiation, and matter (which
carries electric/magnetic charge -- I think that since neutrons spin
they carry some magnetic charge, correct me if I'm wrong) are
stopped by a black globe.  The two nuclear forces are insignificant
to anything inside the field.  Gravity, however, affects it.  I
think I remember something in the High Guard rules involving a
squadron with black globes jumping in so as to glide around a planet
on a hyperbolic course, unglobe, and attack the ground
installations.  In order to do that they'd need to be afffected by
gravity.

Responding to Tim Soholt, I don't believe that gravity propagates
instantly.  Einstein believed that information could not travel
faster than the speed of light, and information in an Einsteinian
sense can be encapsulated in gravity waves (either gravitons of a
particular wavelength/frequency/energy or ripples in the fabric of
space-time, whichever you prefer) if you have a large enough mass as
a transmitter.  I believe that Einstein considered that and came up
with the answer that gravity travels at the speed of light because
it fit the rest of the model well.

Jack Dietz
// [email removed]