__On the Interactions of Point Masses
__

** g**) of a point mass (m

** g**(

In this equation r is the *retarded* distance from
m_{1} to the point (** r**):

r
= c(t-t_{r}) (1a)

and ** u** is a utility velocity vector

** u**
= c<

where <** r**> is the
unit vector of

__v___{ret}
and __a___{ret} are m_{1}’s
*retarded* velocity and acceleration
respectively.

Note that ** r** points from
the

The formula for m_{1}’s
gravitomagnetic field is

** O**(

The force experienced by a
second mass, m_{2}, at (** r**,t)
and moving with velocity

** F**
= m

m_{1}, m_{2},
** g** and

In order to calculate the
motion of m_{2}, Newton’s relativistically correct 2^{nd} law
must be applied.

** F**
= d(m

In many practical
applications where __v___{2}<<c,

** F**
= m

will give satisfactory
results.

__________________________________________________________

1. See ** INTRODUCTION TO ELECTRDYNAMICS**, Griffiths, Second Edition,
Sect. 9.2

2.
See “Roots of Gravitomagnetic Theory” on this website.