diumenge, 16 de febrer del 2020

The great book of the universe

If mathematics is part of the universe that is independent of mind, then can be relatively certain that extraterrestrials will understand our mathematics. If they are an older civilization than our own, they may have read further in the great book of the universe, but we can rest easy in knowing that we are at least reading the same text. Yet if we abandon mathematical Platonism, we immediately find ourselves in more uncertain territory. If mathematics is a product of the embodied human mind, then it is perhaps more accurate to say that we are actively writing one version of the great book of the universe from a uniquely human perspective. Although an extrarrestrial is observing the same universe, their intepretation may be much different from our own if their experience as an embodied mind is sufficiently different. Advances in the cognitive and neurological sciences have revealed how the nature of our phyisical interface with the world –our body– affects our cognition. Thus, it is worth considering whether we can expect an extraterrestrial intelligence to share many physical characteristics with ourselves, which will help inform whether we can expect them to share a similar mathematics.
In some ways, it would be more disturbing to make contact with an intelligent extrarrestrial civilization populated by fleshy, mostly hairless hominids than a civilization of eight-eyed cephalopods, but this possibility is not entirely out of the question. Indeed, as the astrobiologist Charles Cockell has argued, empirical evidence suggests that certain features of life are deterministically driven by physical laws. Extrapollating from this, it is reasonable to believe that "at all levels of its structural hierarchy, alien life is likely to look strangely similar to the life we know on Earth" (Cockell 2018). Cockell's argument is analogous to the case made by Marvin Minsky that extraterrestrials are likely to think like us because they are a subject to the same basic physical constraints. It would be naïve, of course, to suggest that evolution is totally determined by the laws of physics given the significant and obvius role that chance plays in the trajectory of evolution. For example, research suggests that the probability of an asteroid impact resulting in global cooling, mass extinction, and the subsequent appearance of mammals was "quite low" 66 million years ago. It was sheer cosmic bad luck that an asteroid impacted the relatively small portion of the Earth's surface that was rich in hydrocarbons and sulfur that utimately choked the Earth with stratospheric soot and sulfate aerosols. In this case, the site of the asteroid impact changed the history of life on Earth in a way that could never be predicted by deterministic evolutionary laws (Kaiho and Oshima 2017).

The point is that although the trajectory of evolution isn't predictable in advance, the variety of spieces it produces is not boundless. This contradicts the intuitive interpretation of Darwinian evolution, which suggests that natural selection results in a "tendency of species to fom varieties" in infinite number. On the contrary, Cockell (2018) argues that "evolution is just a tremendous an exciting interplay of physical principles encoded in genetic material" and "the limited number of these principles means that the finale of this process is also restrained and universal." Consider, for example, the emergence of cellular life on Earth. Is the cellullar form something that we might expect to emerge on an extraterrestrial planet, or would extraterrestrial organisms find a different mode of self-assembly? In the 1980's, the biologist David Dreamer used carboxylic acids extracted from the famous Murchison meteorite to demonstrate that these simple molecules would spontaneously form cellullar membranes when added to water. According to Cockell, this suggests that the ingredients for cellular life are "strewn throughout the Solar System in carbon-rich rocks." which means "we might expect the molecules of cellularity to form in any primordial cloud, ready to deliver their cargo of protocell material to the surface of an planet with a waiting abundance of water."