[extropy-chat] bidirectional thrust

[Russell Wallace]

On Sun, 20 Mar 2005 16:00:17 -0800 (PST), "Hal Finney" <hal at finney.org> wrote:
> Frame dragging can be considered the gravitational equivalent of
> magnetism.  In electrodynamics, we have electric fields and forces,
> which are pretty simple.  Force is proportional to charge and inversely
> proportional to distance squared.  But then when charges are in motion,
> new forces are created, magnetic forces.  These are vector fields rather
> than scalar fields and the effects are more complex.

Ah! That's clear, thanks.

> Trame dragging doesn't work as an explanation of inertia.  The forces
> are too weak in normal situations to have a significant effect.

I remember reading that it does if the universe is closed. That is, if
you're surrounded by mass sufficient to create a black hole, the frame
dragging effect thereof would equal the normal inertia of an object;
and a closed universe would qualify for this. Is this not correct?

(Of course, there isn't enough mass to close the universe... unless
dark energy counts... would its contribution to frame dragging be
positive? If I understand correctly (which I may not), dark energy
counts as positive for making the universe flat, but negative (due to
its tension exceeding its density) for making it closed.)

- Russell