A Brief Brief History of the Universe
- The ``Big Bang'' brings matter, space, time, etc... into existence
- Almost immediately, gravity begins to form stars (and galaxies of stars).
- Stars are massive balls of primarily hydrogen and helium gas drawn into
dense configurations by gravity.
- Stars are hot enough at the center to cause thermonuclear fusion to occur.
- This process builds heavier elements (e.g. carbon, calcium,
and iron) from lighter ones.
- Fortunately some stars are unstable and they detonate. These stellar explosions return
these ``heavy" elements to interstellar space as raw material
to form the next generation
- The majority of the atoms in you body have been processed through
the interior of at least one star.
- The Sun and Solar System Form
- This event happened 4.6 billion years ago, about 9 billion years after the Big Bang.
- The raw materials available were still 99% Hydrogen and Helium
- That is, thermonuclear processing inside stars produced
1% contamination of elements from the rest of the periodic table
in the intervening time.
- The Earth is selectively constructed from the 1% contamination
of heavy elements (a fascinating story of its own for later in the course...).
- Life originates and simmers on Earth for 4 billion years.
- Its origin and evolution may have been significantly directed by
cosmic events such as supernova explosions, asteroid impacts, and
the formation of the Moon.
- Only 1/2 billion years ago (the most recent 10% of Earth history)
did life begin to develop in complex (multicellular) ways.
- "Intelligence" arose just a few million years ago.
- If Universal history were compressed into a year
- The Solar System formed in early September
- Life arose in mid-September
- Life became complex in early-December
- Dinosaurs roamed the Earth for two weeks between December 10 and December 25
- Humanity (intelligence?) arose at 10 p.m. on December 31
- Recorded history began around 11:59:47 p.m. on December 31