Matter, Anti-matter And Gravity, How is it that Gravity only attracts

[TerenceJohnCo]

I would like to know whether my thoughts below have been considered by others, and any comments would be welcome

1. If all matter in the universe were to become anti matter (by that I mean all mass would become negative relative to the present mass) then the gravitational force would still be positive (attracting) , since the product of 2 negative values is positive. Therefore no-one would know what had happened.
2. Although the effects of gravity are well understood due to Newton and Einstein, there seems to be no explanation as to how it works, and why it is only an attractive force.
3. A way I like to think of gravity is to consider it as a circular polarized wave where all matter is emitting in a (say) clockwise direction when viewed from the source. Then the emission seen from another mass as it comes towards you will be counterclockwise. Thus we have the case where opposites attract, and likes repel.
4. When the Universe came into being, was there as much negative matter as positive?
Could there still be equal amounts of both? Perhaps a white hole at the center?
5. The expanding universe makes sense in that the effects of gravity would otherwise cause a contacting universe unless orbital motions can be assumed to balance out gravitational forces. However, the observation of an expanding universe is an observation of the past, So What is happening "now". If there is an answer to that, is it a fact or just a theory? Observations of various astronomical events are often mentioned as is they actually occurred at the time of observation

[Robittybob1]

I think they will find that matter is positive and negative matter had apart somehow so it does not counteract each other.