Physics Department Seminar University of Alaska Fairbanks

J O U R N A L    C L U B

On Three Fundamental Transitions in the Universe
Juan Roederer
Geophysical Institute, UAF

When we think about the evolution of matter in the Universe, we usually consider a series of causally connected stages: the Big Bang; the gas of unconfined quarks; dark matter; coalescence into hadrons; atoms and molecules; cosmic plasmas; gravitational condensation; formation and evolution of stars and galaxies; annealing of dust grains and the formation of cold bodies like asteroids, planets and moons. But that's not the end of the story. Albeit in only a very tiny region (or regions?) we have the appearance of self-organizing complex matter, living cells, multicellular organisms, neural systems, conscious brains, human self-consciousness and society. A characteristic feature of this last hierarchical chain is that the interactions between the participating complex systems are information-driven, i.e., they are no longer just a linear sum of physical interactions between their constituent parts. Another characteristic is that causation is not "bottom-up" but "top-down", i.e., given one level (e.g., a colony of individual cells), it is not possible to predict, on the basis of laws and initial conditions, the development at a higher level (e.g., how they will eventually assemble and cooperate to form a single organism) – yet higher levels can influence lower ones.

In the whole chain from quarks to humans one can identify three fundamental transitions, which represent truly irreversible, non-causal discontinuities: (1) the quantum-classical transition, with entanglement and its disruption (decoherence) representing the fundamental irreversible mechanism; (2) the appearance of information-driven interactions, with energetically equivalent complex molecules (e.g., nucleic acids) interacting with their environment based on order and form rather than the linear sum of forces; and (3) the appearance of a neural processing system (the human brain) that can work coherently on its own output without any concurrent external information input. Between (1) and (2), and (2) and (3), physical and Darwinian evolution, respectively, proceeds in a continuous manner. I will discuss these three fundamental transitions and their implications for a better understanding of the whole system (including ourselves).

Friday, 20 November 2009
Globe Room, Elvey Building
3:45 PM