The Cosmic Perspective of Cosmology. NOTES: Cosmological Terminology : Cosmology : the study of the large scale structure and evolution of the universe. Homogeneity : the claim the universe has the same density in all locations at the largest scale.
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NOTES: Cosmological Terminology:
Cosmology: the study of the large scale structure
and evolution of the universe.
Homogeneity: the claim the universe has the same density
in all locations at the largest scale.
Isotropy: the claim the universe looks the same in all directions.
though a cosmologist makes up the face of the universe.
and evolution of the universe: in space & time.
Homogeneity: the claim the universe has the same density in all locations at the largest scale. (Center for Cosmological Physics at the University of Chicago)
z = redshift) = Δλ/λ = v/c (for small v = expansion speed)
Counts of distant galaxies and radio-sources appear
to provide evidence that the universe is isotropic.
--ignoring dark energy in space:
In 1998, using Supernova Ia’s,
universe was found to be ruled
by dark energy,
making it accelerate.
We ignore this at first.
= density of universe/critical density
critical density = 10-29 grams per cubic centimeter
(utilizing Einstein’s General Theory):
gave us three possible expanding universes.
Curvature = 0
Omega = 1
Destiny = barely stop expanding,
it reaches a maximum speed but
with no collapse
Curvature > 0
Omega > 1
Destiny = collapse
Curvature < 0
Omega < 1
Destiny = endless
space, they are being carried away
by the expansion of space itself
(like small marks in the surface
on an inflating balloon).
The Big Bang was not like an
explosion in a pre-existing space,
but rather an explosion of space itself.
which resulted in the Inflationary Universe of
Andre Linde (Russia1979)
and Alan Guth (US 1980).
Guth got the Nobel Prize for a theory that didn’t work.
Later, Linde adapted his own theory to one that worked.
a theory of early rapid
1. Horizon Problem The isotropy of the microwave background
indicates that regions A and B in the universe were very
similar to each other when the radiation we observe left them,
but there has not been enough time since the Big Bang for
them ever to have interacted physically with one another.
Why then should they look the same?
slightly from critical density, that deviation grows rapidly in time.
For the universe to be as close to critical as it is today,
it must have differed from the critical density in the past
by only a tiny amount.
Universe is believed to produces North magnetic poles
without a South, but we don’t observe any.
Friedmann’s universe didn’t expand enough to
make them far apart.
space was believed to have undergone a expanded
phase change related to the Grand Unified Theory (GUT)
of elementary particles. (Guth’s Theory). However, this
meant that protons should decay and they don’t.
one expands like ours with a bubble that bursts and explains
the lumpy structure of the universe necessary to produce clusters,
galaxies, and stars. This is called Scale-free lumpiness.
Andrei Linde (now at Stanford) showed this.