"Old Man" <nomail@nomail.net> wrote in message news:3f419367_2@newsfeed...

hanson <hanson@quick.net> wrote in message

"Old Man" <nomail@nomail.net> wrote in message

Old Man is reading a book on cosmology wherein they do the
usual calculation for gravitational collapse time by adding a little
mass at some point in a dust filled uniform and isotropic Universe.
The thought of removing rather than adding a little mass occurred.
What would happen?

Well, all of the dust particles would began and continue to move
away from the mass deficit point in a spherically symmetric
fashion. Anti-gravity? Absolutely yes! But think about it. In
order to remove some mass without a trace, one must introduce
an equal and opposite amount of, not anti-matter which contains
positive energy, but negative matter containing negative mass, and
negative mass should yield a negative gravitational field, or in

words, anti-gravity. No surprises here.

But, think about it some more. In the original problem, where did
that extra little bit of mass come from in the first place? Well,
obviously, it had to come from some other point in space. So, now
do we have a mass dipole with every thing moving away from the
mass deficit point, and everything collapsing upon the mass excess
point? A gravitational mass dipole field? Uncle Al would flame Old
Man to a crisp!

OK. There must be a way out: How does that little bit of mass get
from one point to another ? Well, It can't happen instantaneously,
can it? One dust particle could emit a photon, that gets absorbed

another. Now the emitter and the absorber have exchanged a little
mass / energy and are moving away from each other, each with the
momentum, p = E / c, of the photon. The two dust particles have
a well defined center-of-momentum kinetic energy which gravitates
as a mass monopole. Have we gotten anywhere, or do we still have
a mass dipole moment? One can always create a mass dipole
moment by moving away from the center of mass. There's no rule
against that. Does Old Man get flamed, or not? [Old Man]

No flames. Not by me. I think it's cute.
....Ain't you describing a nano-sized version of the "Executive 9 ball
game" in a cosmic setting? It's essentially a coupled 9 set pendulum.
Your gravitational dipole reminds me of that toy, where there are some
9 steel balls hanging from a frame touching each other.
You lift the outer most one (#1 or # 9) for say 1 inch and
(with the speed of sound in the steel) the outer most on the other end
(#9 or #1) of the row jumps 1 inch away....the impulse traveling thru
the nine balls seven of which appear to remain motionless.
Your view or supposition that this can be seen as a gravitational

I think, is cute. Whether it will supplant existing, classical
explanations that is another question.
regards,
hanson

Hanson has introduced a cute twist: instead of allowing the photon to
be absorbed by inelastic collision on first contact with the absorber,
it bounces back and forth between emitter and absorber via elastic
scattering (reflections) losing a little momentum and energy with each
bounce. In that way, all of the energy of the photon is converted to
kinetic energy of the emitter and absorber with no internal excitation

the absorber. Now the rest mass of the emitter will be less than that

the absorber. So, now, where is the center of mass located? [CoM]
[Old Man]

Cool question. But now the situation moves into the hairier fields.
As long as we restrict/limit the observation just and only to 2 particles
we may have a good chance to conjecture the CoM to be a function of
m1/m2, time and/or with r = c/t, the distance off center, including the
HUP to estimate the most possible locus, actually its smear region r +/-

This 2 particle situaion is more or less just of academic interest......

However, should we entertain the thought of the absorber becoming
and emitter and said emitter passes the (f - df) on to the next absorber
which may have another r separation size then the original/previous pair
had, and/or the direction of this ballistic is not being in a straight

line, and/or the mass of the consecutive absorbers (diff sized dust

and/or their substance properties not being the same, but random.......
........then not only the modeling but even more so the formalized
calculated estimate becomes extremely complicated, if not outright fuzzy,
just like we can observe at a glance anywhere in the real world and of
course in the cosmos with its galaxy sized dustgrain clouds.

That is my first superficial impression of the situation. I'd be delighted
if you or someone could come up with an elegant general formalization
of your conjecture.
Take care,
hanson

PS: There is another elegant post you wrote a while back which entailed:

F = F_newton / sqrt[1- R_s / R]
Where F_newton = GmM / R^2
and R_s = 2GM / c^2 is the Schwarzschild radius. The force
increases faster than F_newton as the sphere density increases
and, as the sphere radius, R > R_s, approaches the Schwarzschild
radius, the force approaches infinity. [Old Man]

I will come back to this when fancy strikes me. Writing this GR dominated
Newton force in explicit form stirred up some curious notions with me, not
least of which was: "What experiments have actually shown that gravity
and em forces have an infinite reach? Who has ever been at or measured
anything infinite?"