Mariner 2, launched in 1962 was the first succesful mission to Venus.

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Mariner 2, launched in 1962 was the first
succesful mission to Venus.
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This picture was radioed back by the USSRs
Mariner 13 spacecraft which lasted for about an
hour on the surface of Venus. The temperature is
over 700F, hot enough to melt lead. The
atmosphere is mostly carbon dioxide, and is about
90 times thicker than Earths atmosphere.
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Venus seen by the Magellan Spacecraft. The dark
areas are smooth lava plains. The bright areas
are rougher older mountain ranges.
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Olbers Paradox
If the Universe is infinite, why is the sky dark
at night?
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The Electromagnetic spectrum spans the entire
range from gamma rays to radio waves. For
electromagnetic waves, c?? Where
c3x1010cm/secthe speed of light, ?wavelength
(we use cm), and ?frequency, in
1/secHertzhzcycles per second.
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The Four Forces

• At a time 10-43 seconds after the Big Bang, we
  first begin to have some (but not yet a complete)
  understanding of how physics behaves. At this
  time, the universe that we can see now was all
  packed into a volume less than 10-40 cm in
  diameter. The temperature was high enough, and
  the density was high enough that the four forces
  that we currently can observe in our universe
  were all unified.
• 1. Gravity
• 2. The Weak Nuclear Force
• 3. The Electromagnetic Force
• 4. The Strong Nuclear Force

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Symmetry Breaking

• Some time after 10-43 seconds after the Big Bang,
  gravity first starts to show a different
  character than the other forces.
• An analogy to this process is the formation of a
  sugar crystal in water as the water cools. When
  the water is warm, the sugar is dissolved. As the
  water cools, the sugar undergoes a phase
  tradition and separates out, and the sugar is
  showing a different character than the water.

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Symmetry Breaking

• Another analogy occurs at a dinner party. Before
  anyone sits down at the table, it is not clear
  which plate each glass belongs to. The first
  person to sit down and choose a glass determines
  which glass all the other persons get.

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Inflation

• By 10-35 seconds, the universe seems to have
  cooled to the point where the strong nuclear
  force should be showing a separate character from
  the electromagnetic and weak forces. During this
  separation, the energy density of empty space is
  not zero. A non-zero vacuum energy density leads
  to a negative pressure.

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At very early times, the expansion rate of the
universe was slow enough so that these regions
had enough time to exchange light signals
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During the inflationary period, the regions of
space that were once in contact are no longer in
contact because space is being created so rapidly
between them that they are expanding away from
each other at faster than the speed of light.
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After the inflationary period, the regions of
space that were once in contact, and that have
since been torn apart begin to come back into
contact with eachother because the rate of
expansion is much slower, and the light can
travel to re-establish connection.
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Timeline for the Big Bang
10-35 to 10-32 seconds Inflation 10-7 seconds
Matter-Antimatter annihilation 10-6 seconds
Formation of Quarks and Antiquarks 1-103
seconds Fusion of Protons into Helium 104
years Universe becomes matter-dominated 380,000
years Electrons combine with protons to make
neutral hydrogen. The Universe becomes
transparent 1 million years Formation of the
First stars.
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The sky as seen in Microwaves. This is a picture
of how the Universe looked when it first became
transparent. The red areas are regions that are
slightly overdense (by about 1 part in 100,000).
The slightly overdense regions eventually
collapsed to form the filamentary structure of
galaxies that fills space.
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This computer simulation shows a volume of the
early universe that contains the gas that
eventually went into the formation of many large
clusters of galaxies. As the simulation proceeds,
this volume expands to larger and larger sizes.
That is, it is participating in the overall
expansion of the Universe. This expansion is not
shown, however, and the box is continuously
rescaled so that it covers the same amount of the
screen. Gravity causes the initially uniformly
distributed gas to collapse into filaments that
eventually become galaxies and clusters of
galaxies. The simulation ends at the present time.
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Simulations showing the formation of the first
stars in the universe http//www.tomabel.com
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This computer simulation shows how galaxies are
distributed on the largest scale. This picture
(which is on a scale nearly a billion light years
across) shows that galaxies (or actually clusters
of galaxies are arranged into a spidery network
of filaments that surround huge voids that are
nearly empty of galaxies. How did this strange
structure arise?
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