Hello Marc. I'm a fan of your work with NASA's "Breakthrough Physics"
program. Nice to see you as a contributor to this group, though I
might suggest putting some type of spam blocker to your address if
this is a usable email address for you.
 I remember reading that Kip Thorne first worked out the mathematics
of wormholes at the request of Carl Sagan as background for Sagan's
book "Contact". Since Thorne also suggested that the material medium
description is equivalent to the warped space-time description of GR
in his book "Black Holes and Time Warps: Einstein's Outrageous
Legacy", he would probably be a good source to find out if black holes
can be described this way.
However, since the book was about black holes I can't imagine he would
say the two descriptions were equivalent if he was not also including
the possibility of black holes.
 Also I recall seeing recently there is some work on creating "lab
versions" of black holes. I think it was by using the material medium
analogy to GR.
 If the material medium description is equivalent to the space-time
description of GR then we should also expect phenomena that occur in
fluid dynamics to occur in GR.
 One that I'm interested in is the Magnus effect:

The Magnus Effect.
http://www.geocities.com/k_achutarao/MAGNUS/magnus.html

 This is an effect that produces a transverse force on a rotating body
in a fluid.
 There is an effect in GR known as "frame dragging". But in the
descriptions I've seen, only the precession of the orbit of a
satellite is described. However, from the mathematical similarity of
the equations of general relativity to those of motion through a
material medium we might also expect there to be a force produced that
drags the satellite in toward the parent body.
 Detecting this inward force in addition to the normal GR
gravitational effect (without rotation) would be one test of this
effect. Another possible test would come from the origins of the
Magnus effect: it's due to the fluid being dragged along with the
rotating body. This results in the speed of propagation of a wave in
that fluid being increased or decreased, depending on direction. Then
light speed should be increased or decreased near a massive rotating
body depending on direction in GR as well.
 I found another interesting comparison to the Magnus effect after a
Google search:

===========================================================================
From: paul vose (paral...@bluesky.net.au)
Subject: Lorentz Force and Magnus Effect compared (and a gif) -
the_same.gif (0/1)
Newsgroups: sci.physics
Date: 1996/12/29

Has anyone ever noticed the similarities between the Lorentz Force and
the Magnus Effect ?

For those who have never heard of either term, a simple definition of
each follows.

---> The Lorentz Force is the centripetal force experienced by a
MOVING CHARGED particle as it travels through a magnetic field. Only
that component of the particle velocity at right angles to the field
is involved. The field does not add any energy to the particle
velocity. The field, the velocity, and the force are always at right
angles to each other, so as the direction of travel of the particle
changes the force also rotates accordingly. The particle ends up
travelling in a circle or a spiral path, depending on the angle at
which it enters the magnetic field. Loss of kinetic energy should also
be taken into consideration. For those who prefer an equation, here it
is..
F = Bq (V sinq), where B is the field strength, q is charge, V is
velocity, and q is the angle between the (total) velocity and the
field. If all of the particle velocity is at right angles to the
field, then sin90 = 1, means maximum force experienced by the
particle.

---> The Magnus Effect is the centripetal force experienced by a
MOVING SPINNING object as it travels through a fluid medium. (The
proviso is that the object be capable of dragging some of the
surrounding fluid around it's 'equator' as it spins - i.e. it needs to
have a rough surface...like a golf ball or a tennis ball). Only that
component of the object velocity at right angles to the spin axis is
involved. The rate of spin does not add any energy to the object
velocity. The spin axis, the velocity, and the force are always at
right angles to each other, so as the direction of travel of the
object changes the force also rotates accordingly. The object would
end up travelling a full circle if gravity and fluid fluctuations did
not act upon it. Golfers and tennis players use the Magnus Effect all
the time, when they use backspin or sidespin to good effect for their
game. Assuming a spinning golf ball travels through the air and drags
some of that air around its equator, it creates a slight vacuum on one
side (at the surface of the ball) where the air is hauled away from
the oncoming wind. On the opposite side, the fluid is thrown into the
oncoming wind and the pressure is increased. The net force on the ball
causes it to change direction continuously. The equation describing
the Magnus Effect is a little complicated for me to describe here.

These two phenomena are extraordinarily similar I think, and it aint
just a coincidence !
=====================================================================

 Then perhaps there is an actual physical interpretation of the
electrons spin as a rotation. There were some attempts to do this
mathematically early on but it was found to require rotation speeds
greater than the speed of light. However, if light speed is no longer
an absolute maximum or if it is allowed to vary this is no longer an
legitimate objection.

     Bob Clark

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