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THE BIG BANG THEORY

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)

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THE BIG BANG THEORY

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  1. 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

  2. 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 - Hubble’s Law • Universe Theories -Big Bang, Steady State • Microwave Background Radiation • Elementary Particle Research

  3. 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.

  4. 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.

  5. THE BIG BANG THEORY • Hubble’s 1929 Data Graphed

  6. THE BIG BANG THEORY • 1966 Data from Reis, Press and Kirshner

  7. 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.

  8. 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

  9. 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 = H*D • Eliminate V, substituting T = D/(H*D) • then T = 1/H = 1/72 km/sec/MPc • T=4.29x1017sec/3.15 x 107sec/yr =14x109yr

  10. THE BIG BANG THEORY • Implications • If there is a maximum size, shouldn’t there be a minimum size? • When did that occur ?

  11. 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.

  12. 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.

  13. THE BIG BANG THEORY • THE STEADY STATE THEORY • In the 1940’s 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.

  14. 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 1960’s from radio telescopes which began to challenge the Steady State Theory. • Then finally it happened …

  15. 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

  16. 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.

  17. 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

  18. BIG BANG THEORY • Einstein’s 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.

  19. 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 Kthe strong nuclear force separates from the electroweak force.

  20. 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.

  21. 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 .

  22. 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.

  23. 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.

  24. 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.

  25. 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.

  26. 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.

  27. 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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