A origem da vida: um problema complicadíssimo para a Física.

quarta-feira, agosto 16, 2017

Origins of Life: A Problem for Physics

Sara Imari Walker

School of Earth and Space Exploration and Beyond Center for Fundamental

Concepts in Science, Arizona State University, Tempe AZ USA; Blue Marble Space

Institute of Science, Seattle WA USA

E-mail: sara.i.walker@asu.edu

Abstract. The origins of life stands among the great open scientific questions of our time. While a number of proposals exist for possible starting points in the pathway from non-living to living matter, these have so far not achieved states of complexity that are anywhere near that of even the simplest living systems. A key challenge is identifying the properties of living matter that might distinguish living and non-living physical systems such that we might build new life in the lab. This review is geared towards covering major viewpoints on the origin of life for those new to the origin of life field, with a forward look towards considering what it might take for a physical theory that universally explains the phenomenon of life to arise from the seemingly disconnected array of ideas proposed thus far. The hope is that a theory akin to our other theories in fundamental physics might one day emerge to explain the phenomenon of life, and in turn finally permit solving its origins.



All else being equal, the thermodynamic benefits of self-replication quantified by Eq. 8 seem to favor the simplest replicators (i.e. the shortest replicators which can replicate and degrade the fastest and therefore maximize entropy production). However, this misses a critical point about information and its role in selection of replicators – all else is not equal. Physical systems encoding the information necessary to replicate fast will do so at an exponential rate [130], whereas sequences of similar length that contain no fitness-relevant information will die. That information and selection matter to life has been one of the most challenging aspects of understanding life as a physical process, and nonequilibrium approaches have yet to address this issue – even if we could identify natural or “intrinsic” macrostates. The forgoing demonstrates that selection for systems that dissipate energy at a fast rate will yield simple replicators. Dissipation is a consequence of selection of information, not a driver of it. Co-polymerization provides one explicit example where dissipation is closely related to information [131]. It seems likely that in the absence of appealing to informational principles, discussions of dissipation and entropy-production alone cannot explain the origins of life (hence Schrödinger’s original appeal to “other laws”).