Tuning the Universe

What is our place in the universe?  Are we a mere accident, the chance result of comingling molecules in a primordial soup, brought into consciousness by a fluke of probability inevitable in an infinite universe?  Are we a necessary extension of ever-increasing entropy, biological machines evolved to accelerate and further entropy’s conquest of order?  Are we, rather, divinely created, the protagonists for which this setting was formed?  Philosophers are wont to ask these questions, but on the frontiers of fundamental physics, they rear their distracting heads to even the soberest of experimentalists.  In particular, they are asked with regards to fundamental constants.

Even if you never took more than a basic physics class, you’ll remember fundamental constants.  In the formulae and equations which describe the behavior of the physical reality around us, these values are the ones you look up in a table, the ones that some brilliant mind derived to make a relationship they observed work mathematically.  On the frontiers of theoretical physics, it is not enough merely to derive what these constants are – physics seeks to explain also why constants have the values observed or calculated.  Some quantities, like the masses and charges of fundamental particles, appear “finely tuned,” in the sense that, if the values were just the slightest bit off from what we observe, matter itself could not form.  Yet we have no explanation, no reason, for why those values are so conducive to forming a universe like ours.

This has given rise to three main schools of thought.  First, there is the statistical inevitability view.  Those who ascribe to the statistical inevitability explanation for the universe’s “tuning” assert that there doesn’t need to be an explanation for these values, that it is simply random chance, and that there are an infinite number of other universes (or possible universes) in which the values are different – we just don’t happen to be in those to take measurements and study such questions.  I saw a reference recently to the idea of the multiverse being akin to an atheist’s God, and that seems especially apt when interacting with this idea of statistical inevitability.

In most direct opposition, then, would be the strong anthropocentric principle, which is a fancy way of invoking a kind of scientific creationism, that the universe must have these parameters in order for us to exist, and therefore the parameters must be tuned in this way – in effect, that the universe was created with these parameters “dialed in” just right so that life like us could arise.  Yes, despite what pundits will say about Copernicus and the radical moving of putting the Earth not at the center of the universe, the question of our place in the universe remains far from settled, and not just for fringe thinkers.

Then there is the weak anthropocentric principle.  Rather than invoking any intentionality to the universe’s creation, or requiring an infinite multiverse to justify the statistical improbability of our universe’s “perfect” conditions, the weak anthropocentric principle asserts that the constants are not tuned at all.  Rather, they only appear tuned to support our kind of life because our kind of life is supported to be observing and measuring them in the first place.  Yes, the values could be anything, but we observe them as what they are because if they were anything different then we wouldn’t be around to observe them.

Kostya Trachenko wrote a fascinating article in a recent edition of Science Advances called “Constraints on fundamental physical constants from bio-friendly viscosity and diffusion,” which studies these questions from a level higher than the most fundamental of parameters to view how those constants affect biologically significant properties like viscosity and diffusion.  It was quite thought-provoking, and he even proposes a sort of fourth explanation, which is that the constants are not so constant as they appear, but rather the result of a kind of universal evolutionary process, in which the universe iterated on those constants until achieving a “good enough” result, like evolution does for biological traits.  Trachenko specifically provides an analogy to the evolutionary paths for human and octopus eyes.  In effect, this is a kind of hybrid between the statistical inevitability view and the weak anthropocentric principle.

Is there an answer?  Will we ever know why the speed of light is the particular velocity it’s measured to be, or why the radius of a circle divides into its circumference precisely pi times, or why the mass and charge of fundamental particles are the exact values they must be for matter to exist?  I don’t know.  Of the explanations presented here, the weak anthropocentric principle appeals most to me, as it requires the least further explanation and raises the fewest additional questions, but that’s a purely rational argument, without empirical methods to support it.  Arguably, maybe it doesn’t matter, but it’s fascinating to think about, and it begs deeper questions.  It also goes to show that, despite how “advanced” we claim to be compared to our “primitive” ancestors, we’re still having the same debates about our place in the universe.  We just frame them differently today.