Evolution explains the fundamental constants of physics

While speaking at TEDxMcGill 2009, Jan Florjanczyk — friend, quantum information researcher, and former schoolmate of mine — provided one of the clearest characterization of theoretical physics that I’ve had the please of hearing:

Theoretical physics is about tweaking the knobs and dials and assumptions of the laws that govern the universe and then interpolating those laws back to examine how they affect our daily lives, or how they affect the universe that we observe, or even if they are consistent with each other.

I believe that this definition extends beyond physics to all theorists. We are passionate about playing with the the stories that define the unobservable characters of our theoretical narratives and watching how our mental creations get along with each other and affect our observable world. With such a general definition of a theorists, it is not surprising that we often see such thinkers cross over disciplinary lines. The most willing to wander outside their field are theoretical physicists; sometimes they have been extremely influential interdisciplinaries and at other times they suffered from bad cases of interdisciplinitis.

The physicists’ excursions have been so frequent that it almost seems like a hierarchy of ideas developed — with physics and mathematics “on top”. Since I tend to think of myself as a mathematician (or theoretical computer scientist, but nobody puts us in comics), this view often tempts me but deep down I realize that the flow of ideas is always bi-directional and no serious field can be dominant over another. To help slow my descent into elitism, it is always important to have this realization reinforced. Thus, I was extremely excited when Jeremy Fox of Dynamic Ecology drew my attention to a recent paper by theoretical zoologist Andy Gardner (in collaboration with physicists J.P. Conlon) on how to use the Price equation of natural selection to model the evolution and adaptation of the entire universe.

Since you will need to know a little bit about the physics of black holes to proceed, I recommend watching Jan’s aforementioned talk. Pay special attention to the three types of black holes he defines, especially the Hubble sphere:

As you probably noticed, our universe isn’t boiling, the knobs and dials of the 30 or so parameters of the Standard Model of particle physics are exquisitely well-tuned. These values seem arbitrary, and even small modifications would produce a universe incapable of producing or sustaining the complexity we observe around us. Physicists’ default explanation of this serendipity is the weak anthropic principle: only way we would be around to observe the universe and ask “why are the parameters so well tuned?” is if that universe was tuned to allow life. However, this argument is fundamentally unsettling, it lacks any mechanism.

Smolin (1992) addressed this discomfort by suggesting that the fundamental constants of nature were fine-tuned by the process of cosmological natural selection. The idea extends our view of the possible to a multiverse (not to be confused with Deutsch’s idea) that is inhabited by individual universes that differ in their fundamental constants and give birth to offspring universes via the formation of blackholes. Universes that are better tuned to produce black holes sire more offspring (i.e. have a higher fitness) and thus are more likely in the multiverse.

Although, Smolin (2004) worked to formalize this evolutionary process, he could not achieve the ecological validity of Gardner & Conlon (2013). Since I suspect the authors’ paper is a bit tongue-in-cheek, I won’t go into the details of their mathematical model and instead provide some broad strokes. They consider deterministically developing (also stochastic in the appendix) universes, and a 1-to-1 mapping between black-holes in one generation of universes and the universes of the next generation. Since — as Jan stressed — we can never go inside black-holes to measure their parameters, the authors allow for any degree of heritability between parent and offspring universes. At the same time, they consider a control optimization problem, with the objective function to maximize the number of black-holes. They then compare the Price dynamics of their evolutionary model to the optimal solution of the optimization problem and show a close correspondence. This correspondence implies that successive generations of universes will seem increasingly designed for the purpose of forming black holes (without the need for a designer, of course).

You might object; “I’m not a black hole, why is this relevant?” Well, it turns out that universes that are designed for producing black holes, are also ones that are capable of sustaining the complexity needed for intelligent observers to emerge (Smolin, 2004). So, although you are not a black-hole, the reason you can get excited about studying them is because you are an accidental side-effect of their evolution.

References

Gardner, A., & Conlon, J. (2013). Cosmological natural selection and the purpose of the universe Complexity DOI: 10.1002/cplx.21446

Smolin, L. (1992). Did the universe evolve?. Classical and Quantum Gravity, 9(1), 173.

Smolin, L. (2004). Cosmological natural selection as the explanation for the complexity of the universe. Physica A: Statistical Mechanics and its Applications, 340(4), 705-713.

Tegmark, M., Aguirre, A., Rees, M. J., & Wilczek, F. (2006). Dimensionless constants, cosmology, and other dark matters. Physical Review D, 73(2), 023505.