Lecture 5: Gaia Hypothesis Flashcards
What approach did James Lovelock take to determining whether life on other planets could exist? What aspect of the planets did he devote particular attention toward?
He looked at the different planets alongside our knowledge of how life affects our planet already. One particular area he looked at was the differing atmospheric compositions
Why were Lovelock’s efforts to determine whether life existed on other planets unpopular amongst his peers?
Because it undermined the credibility of their efforts to determine whether life existed on another planets
What was the conclusion of Lovelock’s work looking at whether life existed on other planets, notably Mars?
That it demonstrated no current or previous indications of life
What do low-entropy/living things do?
They produce high-energy waste products
What do the high-energy waste products match with?
The high-energy waste products are of high disorder which matches with the growing disorder present in the universe
What did Schrodinger state in 1944?
life will always change its surroundings by releasing unusual volatiles and other gases that normally react with each other to vanish, but instead they are maintained causing an unusual mixture in the atmosphere.
What is the idea of disequilibrium?
When things coexist which are highly reactive with each other remain abundant in independent forms
Is the earth in disequilibrium and what is this evident from?
Yes - extreme disequilibrium - evident from the unusual mixture of gases that are highly reactive with each other such as Methane and Oxygen and would normally not be separate
Why is the earth’s atmospheric composition in extreme disequilibrium?
Because life generates large fluxes of gases in order to survive which then alters the atmosphere
What did Lovelock hypothesis from looking at the atmospheric composition over time?
That because the composition has been preserved and stable over time, life must be regulating the atmosphere not just inputting new gases
Who produced the knowledge about the Faint Young Sun Puzzle?
Carl Sagan
What theory did Lovelock develop working with Carl Sagan regarding the faint young sun puzzle?
that is the sun was brighter by 30% before why was it not frozen over? It must have been because the greenhouse gas layer was being altered relative to the sun’s brightness. Vegetation must have been responsible for these changes and therefore alters the climate
What was the Gaia hypothesis?
The theory co-produced by Lovelock and Marguilis which outlined how they believed life was altering numerous aspects of earth
Where did the name “Gaia” come from and what controversy did it have around it?
It was the name of a Greek goddess and it received controversy because it combined quasi and religious ideas
What were some of the topics the Gaia hypothesis wanted to explore?
- Atmosphere disequilibrium, yet stable components
- Why are gases perfectly suitable? e.g. oxygen
- Stable climate despite faint young sun puzzle
- Acidity and redox potential of earth’s surface anomalous yet tolerable
What was the mechanism found in the sulphur cycle that enabled it to recycle?
Dimethyl Sulphide - it resupplied sulphur back to the atmosphere and allowed for sulphur to continue precipitating on the land
What was the mechanism that allowed iodine to be replenished in to the ocean?
Methyl Iodide found in the marine biology
What problems was Lovelock experiencing with getting his Gaia hypothesis to the public? How did he overcome it?
No journal would publish his theory. He would publish a book
Who were two notable peers of Lovelock that criticised his theory? What did they critique?
Dawkins and Doolitle - how could unconscious bacteria consciously determine their environment
What was the name of Lovelock’s response to criticism of his work?
Daisyworld
What was “Daisyworld”?
A model that showed how plants (daises as an example) could automatically alter and regulate their envrionment
What were the two types of plant that he included in the Daisyworld model?
Black Daises - absorb more sunlight which warms their surroundings
White daises - absorb less sunlight
What will happen to black daises if luminosity and therefore temperature reaches a suitable level for growth? What subsequent effect will happen?
They will start to grow - meaning there is more black present which increases temperature more (feedback)
What will happen to black daises when they become too many and temperature reaches too much?
If there are too many daises then the temperature will be too hot so they will start to decline, which dampens the feedback and eventually will vanish as all black daises are gone
