Lecture 13 Flashcards
What is the idea of a life meter?
A device that can tell you how far things are along the path to the evolution of life on other planets / moons etc.
Taking data about physical / chemical conditions in a particular place and return a percentage indicating how close life is to evolving there
Food is. . .
negative entropy
highly ordered
What is a crystal?
A stable structure which has regularity
- DNA is an aperiodic crystal with the capacity to store info
- it is a molecule that can be ordered despite being bombarded with lots of atoms
What makes organisms alive?
The way they receive and process information
PAUL DAVIES:
“Organisms are replete with miniscule machines chuntering away like restless Maxwell demons, keeping life ticking over. They manipulate information in clever, super-efficient ways, conjuring order from chaos, deftly dodging the structures of thermodynamics’ killjoy second law”
How is the orderliness of an organism different to that of crystal?
A crystal is structured in a “periodic crystal.” It is orderly, but it is not living and does not actively maintain its orderliness via exchanging energy, matter and information with the environment. As such, it is more vulnerable to degradation and descending into chaos and disorder than a living organism fighting against “the tides of entropy.”
An organism differs because within it are periodic crystals, such as DNA, but itself isn’t a periodic crystal. An organism does exchange energy, matter and information with the environment in order to survive and actively maintain its orderliness
living things are purposeful things - homeostasis
What does entropy mean?
it is the tendency for the random movement of molecules to spread any local concentration of energy out in
the 2nd law of thermodynamics –> it is the natural tendency for energy in the universe to spread out more and more evenly over time
What is work?
In contrast to heat, work is the energy of a group of molecules all going in the SAME direction (there is an order to their movement). And this order can push molecules into very specific configurations.
living things ‘steal’ order from their environment and they use that to defend or increase their level of order and their level of complexity.
This is what is meant by saying life feeds on ‘negative entropy’ or ‘drinks orderliness’
So if work is using energy in an orderly manner, does that mean the 2nd law of thermodynamics is being violated?
No, because not all the energy from the food is actually going into doing the work. A portion of those molecules RECEIVING that energy don’t cooperate - they shoot off in random directions, and that means the body heats up a bit and the heat spreads from the animal to its environment, decreasing the order of the environment.
How do we measure that heat production in organisms?
using metabolic rate
Homeostasis
- happens at a molecular scale (like the proton pump)
- organism scale (e.g. a shade-seeking lizard)
- amount of info they are able to acquire about both their internal and external
How does order come about in an organism?
- homeostasis
- encoding
What is life?
- exchange of energy, matter, and information
- individuals are special - goal-directed
