Jim talks with Sara Walker and Lee Cronin about the ideas in their Aeon essay "Time Is an Object." They discuss the history of the idea of time, Newton's clockwork universe, the capacity for things to happen, the impossibility of time travel, Einstein's block universe theory, making time testable, conceptions of the arrow of time, irreversibility as an emergent property, the core of assembly theory, measures of complexity, recursive deconstruction, distinguishing random & complex, Kolmogorov complexity, the absence of a useful theory of complexity, counting steps in the assembly pathway, developing theories from measurement, the size of chemical possibility space, the role of memory in the creation of large organic chemicals, memory depth, the assembly index, the origins of life, a sharp phase transition between biotic & non-biotic molecules, life as a stack of objects, a phase transition between life & technology, techno-signatures, error correction in DNA, whether assembly theory is a theory of time, the temporal dimension as a physical feature of objects, implications for SETI & the Fermi paradox, spotting the difference between noise & assembly, the Great Perceptual Filter, looking for complexity in the universe, the probability of life originating, and much more.