For the John Templeton Foundation, I wrote about the concept of the universe’s fine-tuning and its implications across various disciplines.
What does it mean to say that the universe is “fine-tuned”? Scientists who study the origins and nature of the universe have increasingly contemplated this notion — the observation that values of many of the universe’s fundamental constants seem to be both essential for life as we know it, but also apparently arbitrary and potentially improbable, with no reason yet understood why they should have had this numeric value and not that one. Tweak one underlying physical constant slightly, and the universe as we know it — let alone life within it — simply could not exist. In recent years David Sloan, a postdoctoral fellow at the Oxford, has observed an ever-greater variety of ways in which fine-tuning is talked about in the realms of physics, chemistry, and even biology. Particle physicists look at things like the mass of quarks, bosons, and neutrinos. Cosmologists focus on things like the densities of various kinds of energy and matter (both directly observable and “dark”), as well as the cosmological constant, which is the energy density of space.
“When you start reading through this,” Sloan says, “you realize these things mean very different things to different people.” Fine-tuning can mean different things as well to those outside the sciences: philosophers and theologians have used scientific findings of fine-tuned physical symptoms to reach sometimes sweeping metaphysical conclusions, often without a detailed understanding of the science involved.