Download Nineteenth lecture

Origins of the Universe, the Solar
System and the Earth, as we know it
The "Big Bang" occurred 13.5-14 bya, according to astrophysicists &
cosmologists (See? I told you geologists are happy to borrow!)
THIS is believed to be the origin of the ENTIRE UNIVERSE, as we know it!
What was there BEFORE the "Big Bang"?
However, at this time, that's strictly conjecture ...
Yeah, corny ..... everyone knows that with no air, there's no sound!
You're undoubtedly already familiar with:
E=
2
mc
E = energy, m = mass, c = speed of light (299,792,458 meters/sec.)
Turn this around a little, and you get:
E/
2
c
=m
IF you have almost unlimited energy, you can
generate a lot of mass!
Initially after the Big Bang, everything was pure energy
Ultimately, subatomic particles coalesce to create
protons, neutrons and electrons…….
Even then, energy levels are so high that
protons and neutrons bounce off each
other.
Deuterium colliding with a proton can
produce
, which with another
neutron can become helium-4… OR ...
Eventually, they cool down enough to be
able to fuse, forming Deuterium, or 2H
deuterium colliding with a neutron
produces tritium, which can combine
with another proton to produce helium-4.
This Nuclear Fusion is what
generates the energy of stars,
producing the heat and light that we experience at
150 million kilometers' distance!
Initially, matter was distributed surprisingly uniformly
throughout the Universe, as much of it remains today.
90% of all matter in the known Universe
consists of hydrogen and helium!
These gases began condensing into clouds, now
called nebulae (or nebulas)...
YOU ARE HERE!
The nebulae gradually collapse and
commonly start rotating, to form
galaxies, like the Andromeda
Galaxy, pictured here. (Note the
other galaxies also in the picture!)
( Our own Milky Way
Galaxy is a spiral
galaxy )
The first GALAXIES
were probably forming
within 1 billion years of
the Big Bang.
How many stars in a galaxy? Milky Way: 200 billion; Andromeda: 1 TRILLION!
How many
galaxies are out
there?
Galaxies aren't always completely isolated, either, but can interact!
The Doppler
effect
This is also why the
discovery of new
galaxies farther
away than any others
is of major
importance!
From the
amount of the
red shift in
their light
spectra, we can
tell how
rapidly distant
galaxies are
moving away
from us.
Individual large pockets of gas within the spinning disc
of a galaxy can create stars, if they have sufficient mass
(i.e., ~10x the size of Jupiter).
BUT here, the original star didn't last ….
It gradually burned
out, and then
exploded in what
is called a
SUPERNOVA
…. creating a new nebula
that included much
heavier elements than the
old original star elements above iron in the
Periodic Table of the
Elements (the transferric
elements).
Much of our hydrogen and
helium was lost to space, only
some remaining in what
would become the outer
planets (Jupiter, Saturn, etc.).
Heavier debris coalescing within
this gas cloud produced solids,
that coalesced into small bodies
called planetesimals….
…. that then further coalesced
to form larger solid bodies planets - rotating around a
central star …. the Sun.
Soooooo, ultimately we wind up with the solar system we call
HOME. (Ever wonder why all the planets except for Pluto
rotate in the same direction around the sun, in a flat plane?)
The final assembly of our Solar System is
believed to have happened some time around
five BILLION years ago.
But how do we KNOW this???
The process of nuclear fusion can only
generate elements as heavy as iron - with
26 protons and either 29 or 30 neutrons
in the nucleus - within an active star's
core.
Iron
But if we look at the period table, we see LOTS of
elements that are heavier than iron!
The Supernova
is required to generate the
pressures and temperatures to
create these heavier elements!
Wednesday: The EARLY Earth