Saturday, August 11, 2012

40. Cosmic Evolution of Information

It is perhaps a sobering thought that we seem so inconsequential in the Universe. It is even more humbling at first – but then wonderfully enlightening – to recognize that evolutionary changes, operating over almost incomprehensible space and nearly inconceivable time, have given birth to everything seen around us. Scientists are now beginning to decipher how all known objects – from atoms to galaxies, from cells to brains, from people to society – are interrelated (Chaisson 2002).
At the moment of the Big Bang, the information content of the universe was zero, assuming that there was only one possible initial state and only one self-consistent set of physical laws. When spacetime began, the information content of the quantum fields was nil, or almost nil. Thus, in the beginning, the effective complexity (cf. Part 38) was zero, or nearly zero. This is consistent with the fact that the universe emerged out of nothing.

As the early universe expanded, it pulled in more and more energy out of the quantum fabric of spacetime. Under continuing expansion, a variety of elementary particles got created, and the energy drawn from the underlying quantum fields got converted into heat, meaning that the initial elementary particles were very hot and increasing in number rapidly, and therefore the entropy of the universe increased rapidly. And high entropy means that the particles require a large amount of information to specify their coordinates and momenta. This is how the degree of complexity of the universe grew in the beginning.

Soon after that, quantum fluctuations resulting in density fluctuations and clumping of matter made gravitational effects more and more important with increasing time. And the present extremely large information content of the universe results, in part, from the quantum-mechanical nature of the laws of physics. The language of quantum mechanics is in terms of probabilities, and not certainties. This inherent uncertainty in the description of the present universe means that a very large amount of information is needed for the description.

But why does the degree of complexity go on increasing? To answer that, I have to refer to the concept of algorithmic probability (AP) introduced in Part 34 while discussing Ockham’s razor. Ockham’s razor ensures that short and simple programs or 'laws' are the most likely to explain natural phenomena, which in the present context means the explanation of the evolution of complexity in the universe. I explained this by introducing the metaphor of an unintelligent monkey, typing away randomly the digits 1 and 0, each such sequence of binary digits offering a possible 'simple program' for generating an output that may explain a set of observations.

The quantum-mechanical laws of physics are the simple computer programs, and the universe is the computer (cf. Part 23). But what is the equivalent of the monkey, or rather a large number of monkeys, injecting more and more information and complexity into the universe by programming it with a string of random bits? According to Seth Lloyd (2006), ‘quantum fluctuations are the monkeys that program the universe’.

The current thinking is that the universe will continue to expand, and that it is spatially infinite (according to some experts). But the speed of light is not infinite. Therefore, the causally connected part of the universe has a finite size, limited by what has been called the ‘horizon’ (Lloyd 2006). The quantum computation being carried out by the universe (cf. Part 23) is confined to this part. Thus, for all practical purposes, the part of the universe within the horizon is what we can call ‘the universe'. As this universe expands, the size of the causally connected region increases, which in turn means that the number of bits of information within the horizon increases, as does the number of computational operations. Thus the expanding universe is the reason for the continuing increase in the degree of complexity of the universe.

The expansion of the universe is a necessary cause (though perhaps not a sufficient cause) for all evolution of complexity, because it creates gradients of various kinds: The expansion of the universe is a necessary cause (though perhaps not a sufficient cause) for all evolution of complexity, because it creates gradients of various kinds: 'Gradients forever having been enabled by the expanding cosmos, it was and is the resultant flow of energy among innumerable non-equilibrium environments that triggered, and in untold cases still maintains, ordered, complex systems on domains large and small, past and present’ (Chaisson 2202). The ever-present expansion of the universe gives rise to gradients on a variety of spatial and temporal scales. And, ‘it is the contrasting temporal behaviour of various energy densities that has given rise to those environments needed for the emergence of galaxies, stars, planets, and life (Chaisson 2002).
In the grand cosmic scenario, there was only physical evolution in the beginning, and it prevailed for a very long time. While the physical evolution still continues, the emergence of life started the phenomenon of biological evolution:
Although it is difficult to say why the universe is so organized, the measured universal expansion since the Big Bang of space continues to provide a “sink” (a place) into which stars as sources can radiate: A progenitive cosmic gradient, the source of the other gradients, is thus formed by cosmic expansion. For the foreseeable future the geometry of the universe’s expansion continues to create possibilities for functionally creative gradient destruction, for example, into space and in the electromagnetic gradients of stars. Once we grasp this organization, however, life appears not as miraculous but rather another cycling system, with a long history, whose existence is explained by its greater efficiency at reducing gradients than the nonliving complex systems it supplemented (Margulis and Sagan 2002).