I’ve always enjoyed reading the general audience books on physics and cosmology as a general way of keeping up with the broader scientific world. However, I was drawn to Thomas Hertog’s On the Origin of Time based on it’s promise to bring some kind of evolutionary point of view to the origin of the universe and explain this improbably situation we find ourselves in where the laws of physics and the constants are so finely tuned to creating a universe where life can exist.
One potential explanation of our improbable situation is that of a multiverse, where many different versions of the universe exist, but of course we can only find ourselves in a particular one that can support us and our observation.
Hertog throws around many concepts related to natural selection, such as variation and path dependence, where particular accidents become central to our history only because they lie in our path. We know in biology, it is useless to ask why this and not that, in general. We see a particular vertebrate body plan because that’s the plan of successful ancestor from whom we and all other vertebrates descended. Clearly there are other potential paths, which we see in the very different brain and limb organization of insects and cephalopods. But asking why we don’t have 8 tentacles but an octopus does is a meaningless question.
We’re left with studying the path that brought us to this point. Prediction is impossible, we can only delve into the past to understand the accidents that led to us here and now.
But this kind of mapping of the freezing of physical laws is a real stretch.
This meta-evolution has a Darwinian flavor, with its interplay of variation and selection playing out in the primeval environment of the early universe. Variation enters because random quantumjumps cause frequent small excursions from deterministic behavior and occasional larger ones.Selection enters because some of these excursions, especially the larger ones, can be amplified and frozen in the form of new rules that help shape the subsequent evolution. The interaction between these two competing forces in the furnace of the hot big bang produces a branching process—somewhat analogous to how biological species emerge billions of years later—in which dimensions, forces, and particle species first diversify and then acquire their effective form when the universe expands and cools to ten billion degrees or so. The randomness involved in these transitions means that, just like the Darwinian evolution, the outcome of this truly ancient layer of cosmic evolution can only be understood ex post facto.
I don’t find this very illuminating. In evolution we have pre-existing variation. The variations that are stable in their environment persist into the future, which we call selection or fitness, but really is no more than stability. Hertog is positing not pre-existing variation upon which selection can operate, but more of a wandering around between states that eventually is frozen.
Now the idea of the path dependence is clear. And clearly it makes no sense to ask why the Planck Constant has the value it does if it was just frozen into place in the early universe, but Hertog offers no reasons for why those particular values that can support complex biology got frozen in other than to say that we are here, those are the values, and there is no final theory to be found.
I was hoping that Hertog had some explanation of why, during that early variation of the laws of physics, states that could support more complexity might survive and get baked in compared to sets of laws that lead to a quick recollapse of the early universe or a flat, uninteresting universe without large scale structure of galaxies and planets.
It seems to me there must be something to this idea that complexity is more stable, so it is understandable that we find ourself in this kind of universe. An immediate recollapse seems rather pointless. Our lives on the this rock moving through space asks us to find a reason for our existence here.