The energy we call spiritual is part of that spectrum. The Japanese call it Ki the Chinese call it Ch'i.
Wow: Ki and ch'i have a lot in common. But the understandig of ki and ch'i is quite different in a lot of points. It isn't just a chinese or japanese word for the same thing.
Ki in japanese understanding has a lot to do with "intention", "will" or "feeling". Do you think, that this can be put together with X-rays, gravitation, magnetism or other "energies" described by natural sciences?
We just mostly call it a higher power( unless we use another cultures word)..
What do you mean by "higher power"? If it's supernatural, it's a religious phenomenon. (By definition, I think.)
(But I don't think it's supernatural.)
You don't need books, rituals ...
aaahhh I'm sorry my english is too bad to express my thaughts clearly.