what is the "density" exactly means?

[Peregrinus]

where did you get that number ? and the 70-80 date ?

Q'uo stated that the harmonic convergence of Aug 16/17 1987 (dependent upon location on Gaia) was when duel activated mbsc began incarnating here.

I believe the 35k number ZenM speaks of was those harvestable 1981-1984. All those born after the harmonic convergence are ascendable and duel activated, either of Earth, or from elsewhere and requiring a 4D planet.

then there comes the question of density difference. will or will not this entity be able to live in a totally different 'dimension', which will be untouchable/nonphysical to 3d ...

As I believe Ra stated, it is possible for these to coexist, but due to the range of differences, the 3D mbsc finds the 4D mbsc to be quite disconcerting. it is for this reason that these two densities have not been mixed until the fourth density mbsc have learned to 'shield' themselves and their manifestations from view of 3D mbsc.

63.8 Ra: I am Ra. ... As the green-ray cycle or the density of love and understanding begins to take shape the yellow-ray plane or Earth which you now enjoy in your dance will cease to be inhabited for some period of your space/time as the space/time necessary for fourth-density entities to learn their ability to shield their density from that of third is learned. After this period there will come a time when third-density may again cycle on the yellow-ray sphere.

Meanwhile there is another sphere, congruent to a great extent with yellow ray, forming. This fourth-density sphere coexists with first, second, and third. It is of a denser nature due to the rotational core atomic aspects of its material. We have discussed this subject with you.

The fourth-density entities which incarnate at this space/time are fourth-density in the view of experience but are incarnating in less dense vehicles due to desire to experience and aid in the birth of fourth-density upon this plane.

Yes I know the quote above does not specifically answer your question. I am searching Ra/Q'uo for the specific answer you seek.