chi,
some thoughts that may be interesting.
Imagine we have a star and a planet orbiting the star. and that's all we have.
The planet is orbiting and because of this it is applying a centrifugal
pressure on the star. The stars position always being relevant to the planet.
Logically this would not work to well if we want the star to stay relatively still in its role as fulcrum.
Logically we would have to have a counter balance on the planet on the other side of the star.
Negative mass comes to the picture. but inversley applied..( I looove that word...inverse)
So we have this phantom negative mass on the other side of the star but to countwieght the planet it has to have mass ( a centre of attraction) in this dimension so it's mass attraction is inverse to the negative mass.
Or for a better way to describe it exists in the realms of neg mass dimension but it's actual mass value and not the negative physical mass is in the planets positive dimension. so we have a counterbalance to the planets pull on the star. And theoretically this could be applied to all planets so that when the planets lign up there is no effect on the suns position as the counter balancing would neutralise it.
May be if we look for a counter balance for Mars when it is in a good position we may detect something...just an idea.
I do remember reading some where some one working on this possibility but I can't remember the details