Properties of Ki as related by O sensei

Hello everyone,
I am an undergraduate psychology major at university and am doing some searching for information for a possible research project. Does anyone know if O sensei ever discussed (e.g., with Nadeau shihan or others) or wrote on the nature of ki and its different manifestations throughout the universe? Specifically, I am looking for information on physical properties that ki may take on. I am looking for as much and as varied information as possible; if anyone could direct me to a piece of writing or other source of information or tell me what was said, I would be very appreciative.
Thank you very much,
Jake L.

There is a book by Mitsugi Saotome: "Aikido and the Harmony of Nature" which talks a lot about the nature of ki. I don't know if this is what you are looking for, but I just figured I should suggest it. Good luck with your searching