If something exists and works on humans, it exists and works through the material universe we inhabit - even if it's origin is some teeny-tiny ultra folded dimension or similar, it has a material effect on a material object, and therefore it's testable.
But since the stuff out of which the apparent material universe is made isn't material, it's not really a material universe that we inhabit, it just looks like that from our point of view (mostly).


I *heart* the holographic theory 

(and they're made from the crushed pelvic bones of children)