The word "immaterial" means something that is insignificant or not relevant to a situation or discussion. It is often used to describe things that are not important or don't have any influence on a particular matter. Full definition
Beginning in the late 1960s, he turned to the representation of immaterial phenomena in nature such as wind, fire, water, smoke, and fog. (levygorvy.com)
Pain becomes immaterial in the absence of suffering. (mindbodygreen.com)
How does something as physical as the brain create something as immaterial as your sense of self? (newscientist.com)