lundi 19 janvier 2009

「生命を定義する」 Définir la vie (8)

5 février 2008

Radu Popa "Defining the living state via understanding early stages in its evolution"


Introduction to xenobiology (宇宙生物学とは)
  ● non-earth-centric description of life, origin, early evolution, macroevolution
  ● no sharp transition between life & non-life
  ● no one molecule, structure, force-started life
  ● being alive is independent of any particular composition
  ● origin of life: both probability & causality involved
  ● origin of life: placed at intersection between disequilibrium thermodynamics & theory of information

  ● xenobiology is different from astrobiology

Definition of Life
  living entities are self-maintained entropy dissipating system
  1) energy dissipative self-maintenance
  2) adaptive evolution based on genetic system = learning changes in controlling mechanisms

increasing energy dissipation : lot of energy into out
but no genetic memory
cf. digitizing information; remember the change, but not genetics

Origin of life
chance vs. causality
one big step or many small changes?

Causal origin of life

● life drivers:
   time-asymmetric physical laws (non-random functioning of the Universe), post-Big-Bang
● anthropic principle --> physicist view
● non-random organization of the Universe

Aucun commentaire: