In so far as physicalness is the reference, whatever is not tangible in that way, is nothing.
And then there are degrees of tangibility where one range of frequencies are perceptible but another higher or lower range is imperceptible.
Science did a huge favor by demonstrating the use of higher and lower frequencies while using a human body detecting equipment (ear and eye) to prove that intangible aspects can be real. Xray machines for example.
Indeed, just as in the vein of the practice, the source of the motivation, and the process(es) all yield different results. And, so true, nearly any genuine approach can lead to some results worthy of study or consideration within the boundaries of their own merits.