Well, a word is true as given by its defintion, because that is words work. In effect if the defintion of the universe is that is physical, then it is true that the universe is physical.
BTW that is also how this defintion work and how it is true. God as per one definition: the creator and
ruler of the universe and source of all moral authority; the supreme being.
That is how defintions and axioms work. They make it true objectively as an objective fact. By defintion the word blü 2 is an evil human.
And the axiom is that I am rational and you are not.