EPSC 185 Lecture Notes - Lecture 6: Radioactive Decay, Silicate Minerals, Continental Drift
23 Jun 2018
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Geology and earthquakes
The steady state theory
-They said that matter is continuously created at a rate that keeps the average density of the
universe the same as it expands
-Universe has always existed, no beginning and no end, eternal existence
-Matter alone exists for an infinity of time
The big bang theory
-Lemaitre (1931) declared that the universe has a beginning and that it was expanding as a
result of something that had triggered it
The formation of earth:
-Bing bang theory- primeval atom, a condensed atom ball the size of the golf ball exploded and
became what it is today.
-The singularity point of view sees energy instead of quarks into golf ball. No explosion but the
energy just expanded and created the matter in the universe.
-A single point of concentrated energy exploded
-Assumes that all parts of the universe began exploding simultaneously
-All matter and energy was initially packed in an infinitesimally small point
-Astronomers concluded that expansion begun at a certain time with a cataclysmic explosion
-The big bang is the accepted theory of the origin of the universe in the scientific community
-Occured 13-18 billion years ago
-Evidence was found in space in 1964.
-The cosmic microwave is what its called.
-The immense heat of the explosion caused: fusion and quarks (fundamental particles), formed
protons and neutrons
-Hydrogen begun to populate the universe
Collision and fusion of hydrogen atoms
-Nucleosynthesis (happened before any stars formed)
> 1 second < 5 minutes
after big bang
Earth formation (brief summary)
Big band nucleosynthesis
1- first stars initiated nuclear fusion ~1 billion years after the big bang
a) fashion of 2h to 4he
2- friction between particles increased
Increased heat allowed for the fusion of helium into carbon
b) 4he + 4he —> 8be + 4he —> 12c
Stellar nucleosynthesis
3- small amount of 16O is also produced by adding 4he to 12c
New phase of star collapse sees
c- 12c + 12c —> 24mg —> 20ne + 4he
d- 16O + 16O —> 32s —> 28si + 4he
Production of even numbered elements up to iron (fe)
Our solar system
-Our sun was formed in a nebula consisting of remnants of supernova
—> Second generation star (h and he)
-Gravity pulls gas and dust inward to form an accretionary disk and a proto-sun forms at the
centre
-Inner planets (mercury, venus, earth, mars) formed by coalescing of planetesimals
(collision of dust particles) in the inner rings close to the sun
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
They said that matter is continuously created at a rate that keeps the average density of the universe the same as it expands. Universe has always existed, no beginning and no end, eternal existence. Matter alone exists for an in nity of time. Lemaitre (1931) declared that the universe has a beginning and that it was expanding as a result of something that had triggered it. Bing bang theory- primeval atom, a condensed atom ball the size of the golf ball exploded and became what it is today. The singularity point of view sees energy instead of quarks into golf ball. No explosion but the energy just expanded and created the matter in the universe. Assumes that all parts of the universe began exploding simultaneously. All matter and energy was initially packed in an in nitesimally small point. Astronomers concluded that expansion begun at a certain time with a cataclysmic explosion.
