Sorry, but i dont think, that scientists would search for a material, that would be implantable, dense and very light to create humongous breasts like chelsea charms or beshine weighting around 2 or 4 kg.
There are only a few girls who are willed to go bigger than 2000ccs i think. Most girls prefer an implant size around 300-600ccs. And this volumes doesnt need to be very light. And thats why there are no great need of creating an perhaps expensive material that is very light and implantable.
I am dreaming too of breasts that are two round orbs perhaps 1/3 or half of the body volume of the girl, but i dont think, that scientists doesnt search for it, cause there is no need for it and it has to be good to sell...
But never say never
