The article is actually about models in which spacetime is an emergent property of more fundamental structures: string theory and loop quantum gravity. Both face a lack of experimental evidences validating their predictions.
Succinctly describes the global zeitgeist.
Perhaps modern idioms are to blame with relation to the copula. We seem to say things are what they are without a qualifier on what type of existence it has.
> But string theory is difficult to understand—it lives in mathematical territory that has taken physicists and mathematicians decades to explore. Much of the theory’s structure is still uncharted, expeditions still planned and maps left to be made. Within this new realm, the main technique for navigation is through mathematical dualities—correspondences between one kind of system and another.
One can believe that’s a form of truth but people should be conscious that it is merely a belief.
Observe that the model itself worked quite well regardless of the base reality. Knowing that truth doesn’t change any current applications. But who knows where it’ll lead. So knowing which model is successful and which model is real is a very important question that we must try our best to answer. Only in the natural sciences can such a question even be answered.