THE BIG BANG THEORY

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THE BIG BANG THEORY

• The Big Bang Theory will be an illustration of
  how a theory develops by modeling.
• Text references Physics Potpourri on pages
• 228-229, 320-321, 454-455, 508-510, Prologue
  (p. 2-10) and Ch.12-2 (p. 472-479)
• Suggested readings p.245 W. Freeman p.317 S.
  Weart p.445 R. P. Kirshner
• Web reference http//rst.gsfc.nasa.gov/Sect20/A1.
  html

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THE BIG BANG THEORY

• The BIG BANG THEORY is composed of a combination
  of several experimental phenomena and theories
  which have developed over a period of 100 years.
  
• These are
• Expansion of the Universe - Hubbles Law
• Universe Theories -Big Bang, Steady State
• Microwave Background Radiation
• Elementary Particle Research

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THE BIG BANG THEORY

• NEW EVIDENCE (PHENOMENA)
• By 1925 V. Slipher measured the speed of galaxies
  and found that all galaxies greater than 3
  Million Light Years were moving away from the
  earth.
• By 1929 Edwin Hubble found that those galaxies
  close to us were moving slower and those further
  away were moving faster.

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THE BIG BANG THEORY

• UNITS FOR LARGE DISTANCES
• Light is the speed of an electromagnetic wave.
  It has a value of c 299,792,458 m/s.
• We write this in shorthand notation approx. as
  3.00 x 108 meters/s or 186,000 miles/sec
• The distance light travels in a year is
• a LIGHT YEAR (LY) 9.46 x 1015 m.
• A parsec (pc) is 3.26 LY 3.09 x 1016 m. Parsecs
  is a measure of galactic distances.

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THE BIG BANG THEORY

• Hubbles 1929 Data Graphed

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THE BIG BANG THEORY

• 1966 Data from Reis, Press and Kirshner

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THE BIG BANG THEORY

• These data led to the Hubble Relationship
• V H D
• where V is the velocity of the galaxy
• H is the Hubble Constant 72 km/s/MPc
• D is the distance to the galaxy
• Implications The further away a galaxy is from
  the earth, the faster it is receding.
• Since no matter can travel faster than the speed
  of light, the universe has a max size.

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THE BIG BANG THEORY

• A PREDICTION OF THE SIZE OF THE UNIVERSE FROM
  HUBBLE CONSTANT
• Method Find the distance of a galaxy when it is
  traveling at the speed of light.
• V H D
• V c 3 x 105 km/s H 72 km/s/MPc
• D V/H 3 x 105 km/s/72 km/s/MPc
• D 4.17 x 103 MPc 14 x 109 LY

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THE BIG BANG THEORY

• A PREDICTION OF THE TIME OF THE BIG BANG FROM THE
  HUBBLE CONSTANT
• Method Find the time for a galaxy to be
  traveling at the speed of light.
• T D/V (time distance/velocity)
• But the Hubble relationship is V HD
• Eliminate V, substituting T D/(HD)
• then T 1/H 1/72 km/sec/MPc
• T4.29x1017sec/3.15 x 107sec/yr 14x109yr

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THE BIG BANG THEORY

• Implications
• If there is a maximum size, shouldnt there be a
  minimum size?
• When did that occur ?

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THE BIG BANG THEORY

• THE FIRST THEORIES OF THE UNIVERSE
• Albert Einstein developed the General Theory of
  Gravitation and with it he developed a steady
  state theory. He later recanted his theory since
  he had introduced a Cosmological Constant which
  was wrong.
• W. de Sitter proposed an expanding universe
  model.
• In 1922 A. Friedmann modeled a universe that
  expanded at different rates.

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THE BIG BANG THEORY

• THE FIRST GOOD THEORY IMPROVEMENTS
• On the basis of the early galactic data,
• in 1927 Georges Lemaître proposed that the
  universe began with the explosion of a primeval
  atom.
• In 1948 R. Alpher, H. Bethe and G. Gamow theorize
  the process of nuclear synthesis.
• They explain how Hydrogen and Helium can produce
  heavier elements.

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THE BIG BANG THEORY

• THE STEADY STATE THEORY
• In the 1940s F. Hoyle, Bondi and Gold develop
  the Steady State Theory of the Universe and the
  means by which the theory can be tested.
• This theory stated that the universe remains
  constant.

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THE BIG BANG THEORY

• THE STEADY STATE THEORY
• There now was competition between the Steady
  State and the Big Bang Theories.
• Experimental evidence was coming in during the
  early 1960s from radio telescopes which began to
  challenge the Steady State Theory.
• Then finally it happened

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BIG BANG THEORY

• FINAL EXPERIMENTAL EVIDENCE
• In 1965 A. Penzias and R. Wilson detected the
  remnant radiation from the Big Bang. It is
  microwave radiation with a temperature of 3K.
• In 1990 the COBE satellite measured that
  radiation with precision to find 2.725K

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THE BIG BANG THEORY

• Now that THE BIG BANG THEORY has been
  established. Scientists have used research in
  Elementary Particle Physics and Astronomy to
  establish a time line of evolution of FORCES,
  FIELDS and MATTER to produce the observable
  Universe we know today.
• In the BBT time lines are divided into ERAS
• Let us outline the evolution of our universe
  as presently known from the Big Bang Theory.

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BIG BANG THEORY

• At the beginning the first manifestation of an
  observable quantity was pure energy.
• This energy was concentrated at a point (an
  extremely small volume) and this situation was
  equivalent to an extremely high temperature.
• Scientists can not measure observable quantities
  until time begins and then we have the beginning
  of our universe.
• The entire universe as well as the four forces
  are combined in that huge amount of energy

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BIG BANG THEORY

• Einsteins equation E m c2 means that
• Energy is matter. Since gravity is available
• then some of the energy can turn to matter.
• The process is called PAIR-PRODUCTION or the
  creation of matter from energy and was predicted
  by P. A. M. Dirac in 1928.
• It was verified in the laboratory in by Carl
  Anderson in 1932.

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BIG BANG THEORY

• SUPERSYMMETRY ERA
• At a time of 10-43 sec, after the Big Bang
  the temperature is 1032 K, the gravitational
  force separates from others, matter is created by
  pair production and there is a zoo of weakly
  interacting particles. Radiation predominates.
• THE GRAND UNIFIED THEORY ERA
• At a time of 10-34 sec and temperature of 1028 K
  the strong nuclear force separates from the
  electroweak force.

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BIG BANG THEORY

• THE INFLATIONARY ERA
• Suddenly the size (volume) of our universe
  increases 10 50 times at a time of 10 -32 sec
  when the temperature is 10 27 K.
• All the heavy particles and their quarks are
  created by pair production and are in
  equilibrium.

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BIG BANG THEORY

• HAWKING RADIATION
• Hawking Radiation occurs during pair production
  near a miniature black hole. At pair production
  the antiparticle is absorbed by the small black
  hole and the normal particle escapes. This
  particle moving away is the Hawking Radiation.
  The black hole then begins to slowly evaporate as
  it picks up more antimatter. A great example of E
  m c2 .

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BIG BANG THEORY

• RADIATION ERA
• At 10 -10 sec and T 1015 K electromagnetic and
  weak nuclear forces separate.
• HEAVY PARTICLE ERA
• At 10 -7 sec and T 1014 K photons collide to
  form protons and neutrons by pair production.

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BIG BANG THEORY

• LIGHT PARTICLE ERA
• At 10-1 sec and T 1012 K photons collide to
  form electrons and positrons by pair production.
• COSMIC BACKGROUND ERA
• At 1 sec and particles and T 1010 K
  antiparticles annihilate. The residual matter is
  now protons, neutrons and electrons. This was
  caused by asymmetry.

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BIG BANG THEORY

• NUCLEOSYNTHESIS ERA
• At 3 minutes and T 10 9 K nucleosynthesis
  begins to form nuclei of hydrogen, helium and a
  little of beryllium and lithium. Then ions
  formed and a significant increase in cooling
  occured.
• Dr. Calamai here at ASU has a NSF grant for three
  years to study the ions which cooled the
  universe.

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BIG BANG THEORY

• MATTER ERA
• At 3x 105 years and T 103 K matter and the
  cosmic background decouple.
• Electrons bind to the nuclei and atoms are
  formed.
• GALAXY FORMATION
• At 109 years and T 18 K the asymmetry in matter
  causes matter clusters to begin forming galaxies
  and stars. Fusion starts.

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BIG BANG THEORY

• PRESENT EPOCH
• Planets and solar systems are formed at the times
  of stellar formation. When stellar fusion uses
  all the hydrogen, then the star begins to use
  helium and create carbon. Then the star explodes
  and causes asymmetry which generates new stars.
  This process repeats itself.
• At 14 x 109 yr and 2.725 K, it is today.

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Hubble Telescope Image

• The next slide is a remarkable image taken by the
  Hubble Space telescope of galaxies.
• One sees some galaxies close up, others are
  just a point of light.
• Estimates are that there are over 100 billion
• galaxies in our universe.

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