The birth of spacetime atoms as the passage of time.

In the following discussion I suggest that the reason there is no consensus on whether the passage of time is physical is that our current best theory of spacetime, general relativity, lacks such a concept. This means that the sense-experience of passage, appealed to by those who claim it is physical, cannot be properly expressed: it is not even a fact. I draw attention to work in the literature on a model of a growing, granular spacetime--arising within a proposed theory of quantum spacetime called causal set theory--that does contain the concept of passage as the coming into being or birth of atoms of spacetime. I present an example from the history of science of a sense-experience that cannot be understood within one theory but is revealed to be an important fact within a better successor theory.