Earth, Our Environment - Class Notes
Chapter 2, Earth: Origin and Composition - 01
The Big Bang Hypothesis
The fundamental particles that make up everything we know to exist were created at the formation of the Universe, which began with the "Big Bang". Approximately 15 billion years ago (actually 10-20 billion is the estimate), the Universe exploded into existence.
The observational evidence for the Big Bang includes:
- Hubble's observations on the motion of galaxies
- The observation of uniform cosmic background radiation
- As well as some consistency arguments on the time it takes to form the observed galaxy clusters and atomic elements.
The universe-forming "bang" was enormously energetic and the resulting temperature was high. Elementary particles existed for fractions of a second and began to coalesce with time, forming the familiar particles of atomic physics. Additionally, the fundamental forces in the Universe began united in one system:
Elapsed Time
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Transition
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10^-43 second
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Quarks and Bosons be come interchangeable & Gravity force separates
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10^-35 second
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Electroweak and strong forces separate
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10^-10 second
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Weak and electromagnetic forces separate
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1st millisecond
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Particles form from quarks
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3-4 minutes
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Hydrogen and Helium nuclei form
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1 billion years
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Protogalaxies form
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Prepared by: Charles J. Ammon
cammon@geosc.psu.edu
February 1997