• diffusion
• chemical reactions
• genetic regulation
• negative feedback in organisms
• negative feedback in ecosystems

autonomy

• brownian motion
• oscillating chemical reactions
• cell cycle
• circadian rhythms
• positive feedback in action potentials, sex cycle
• population oscillation

• assembly rules - covalent bonding
• hydrophilic/hydrophobic
• epithelia

diversity

• atoms
• molecules
• cell constituents
• cells
• cellular assemblies
• organisms
• populations
• terras?

improbable assemblies of improbable assemblies

combinatorial explosion

flux

variation

interdependence

recognition

spatial organization/specificity

• enzyme structure
• organelle structure
• cell structure
• organ structure

recursion

cycles

• enzymes
• photosynthesis, fermentation, Krebs
• menstrual (?)
• carbon and geochemical

use improbablity to make improbability

randomness

• diffusion
• chemical reactions
• meiosis
• mutation
• immune system
• brain

specializaton (and interdependence)

• enzymes/info molecules vs ribozymes
• enzyme specificity (vs heat)
• prokaryotes vs eukaryotes
• multicellular organisms
• ecological niches

distributed control

adaptation vs self-organization

reproduction, history-dependence

energy transformation, matter recycling

things that can be developed but not constructed

• capillary beds
• interconnected neurons
• immune competence?
• relation to Turing, halting problem, history dependence, fractals

Compare and contrast definitions of life and/or science in lecture/discussion and in Tobin and Dushek

Life .... ?

Living organism? How tell? Start with preconceptions ....
Practical problem .... life elsewhere in universe? ... how recognize?

• Europa, one of Jupiter's moons, from Galileo
• Mars, from Pathfinder
• Life on Mars?, from Earth
• Beyond the solar system?, from the SETI Institute

• semi-homeostatic
• semi-autonomous
• reproducing with variance
• energy-dependent
• varying and variable
• bounded
• highly improbable assembly .... of physical elements
  (Improbable assemblies from simple interactions of simple things?)

LIFE is an interacting and interdependent array of diverse living organisms at multiple scales

• interacting boxes each made up of interacting boxes each made up of ...
• requires study at multiple levels of organization ranging from atoms through molecules, molecular assemblies, cells, cellular assemblies, organisms, populations, ecosystems

Where does "fit" come from? Why persisting variability and change? Accident ...imperfection?

LIFE is an ongoing process of exploration, of generating and testing hypotheses about the surroundings.

Evolution:
• dependent on prior observations and random change ("creativity"?!), selection ("experiment")
• no perfect organism ("Truth")
• no "mistakes", only hypotheses, which influence one another