The Big Picture: On the Origins of Life, Meaning, and the Universe Itself

by Sean Carroll

The different stories or theories use utterly different vocabularies; they are different ontologies, despite describing the same underlying reality. In one we talk about the density, pressure, and viscosity of the fluid; in the other we talk about the position and velocity of all the individual molecules. Each story comes with an elaborate set of ingredients—objects, properties, processes, relations—and those ingredients can be wildly different from one story to another, even if they are all “true.” Each theory has a particular domain of applicability. The fluid description wouldn’t be legitimate if the number of molecules in a region were so small that the effects of particular molecules were important individually, rather than only in aggregate. The molecular description is effective under wider circumstances, but still not always; we could imagine packing enough molecules into a small enough region of space that they collapsed to make a black hole, and the molecular vocabulary would no longer be appropriate. Within their respective domains of applicability, each theory is autonomous—complete and self-contained, neither relying on the other. If we’re speaking the fluid language, we describe the air using density and pressure and so on. Specifying those quantities is enough to answer whatever questions we have about the air, according to that theory. In particular, we don’t need to ever refer to any ideas about molecules and their properties. Historically, we talked about...