Temporal becoming in a relativistic universe: causal diamonds and Gödel’s philosophy of time

Abstract

The theory of relativity is often regarded as inhospitable to the idea that there is an objective passage of time in the world. In light of this, many philosophers and physicists embrace a “block universe” view, according to which change and temporal passage are merely a subjective appearance or illusion. My aim in this paper is to argue against such a view, and show that we can make sense of an objective passage of time in the setting of relativity theory by abandoning the assumption that the now must be global, and re-conceiving temporal passage as a purely local phenomenon. Various versions of local becoming have been proposed in the literature. Here I focus on the causal diamond theory proposed by Steven F. Savitt and Richard Arthur, which models the now in terms of a local structure called a causal diamond. After defending the reality of temporal passage and exploring its compatibility with relativity theory, I show how the causal diamond approach can be used to counter the argument for the ideality of time due to Kurt Gödel, based on his “rotating universe” solution to the Einstein field equations (the Gödel universe). I defend the second component of his argument, the modal step, against the consensus view that finds it wanting, and reject the first step, showing that the Gödel universe is compatible with an objective passage of time as long as the latter is construed locally, along the lines of the causal diamond approach.