Lecture 1 - Big Bang, Chemical Elements, Galaxies PDF

The Big Bang, Chemical Elements and Formation of Galaxies Global environmental Processes ( GEOG1020 E1) Dr Lawal Billa  What is the Big Bang ? The theory that states that the Universe begun to expand with the explosion of concentrated...

The Big Bang, Chemical Elements and Formation of Galaxies Global environmental Processes ( GEOG1020 E1) Dr Lawal Billa  What is the Big Bang ? The theory that states that the Universe begun to expand with the explosion of concentrated matter and energy. no concrete evidence The universe begins as the size of a single atom and exploded in a violent expansion All matter and space were created from that single point of pure dense energy in an instant  Combination of Cosmological Principals and general Relativity  About 14 Billion (13.7billion) years ago  Giant ball of matter (Nucleosynthesis), Alpher-Bethe-Gamow(1946)  Hubble’s Law (1929) the expansion is natural  Red Shift if some objects are farther away, red glow can be seen; gives idea that the universe is in expansion mode  Supporting Evidence for Big Bang key points: 1) Universal expansion (Red Shift) and Hubble’s Law 2) 3 degree background radiation (Cosmic microwave radiation proved in 1965 Bell Lab) 3) Quasars 4) Radioactive decay(Abundance of lighter elements, Li, H, He, Be) 5) Stellar formation and evolution 6) Speed of light and stellar distances 1. Universal expansion and Hubble’s Law Hubble observed the majority of galaxies are moving away from us and each other The farther, the faster they move Red Shift 2. Back ground radiation Noise radiation is static, evenly spread across space The amount of radiation matched predictions Satellite also confirmed that in the entire universe noise radiation is static and evenly spread Law of conservation of energy (energy can neither be created or destroyed) – energy remains constant over time 3. Quasars Super large (solar system size) galactic cores that put out more light than whole galaxies Only found 10-15 billion light years away Found nowhere else Nothing exists past them  4. Radioactive decay Radiometric dating – gives us the age of items from the decay of radioactive materials found within the object where they come from Moon rocks have been dated and found to be older than Earth – Gives us an estimated time that Earth and the Moon formed  5. Stellar formation and evolution Satellites and telescopes are used to observe the life cycles of stars across the universe. These instruments view stars form, burning and explosion 6. Speed of light and stellar distances The speed of light is a universal constant of 300,000 km/s2 We are able to observe stars millions/billions of light- years away A light-year is the distance that light travels in 1 year – the light we see today from a star 500 light years away is 500 years old The furthest stars away are 10-15 billion light years away  Arguments Against the Big Bang Theory 1. Too much energy how did big bang start if theres no energy before  Most of the universe is empty space: a vacuum which is defined as a volume containing no particles, force fields, nor waves. By definition a vacuum has no energy. However, the Big Bang theory requires both in its early and later phases that the vacuum must have some energy.  The law of conservation of energy demands that energy cannot be created nor destroyed. 2. Complex theory and too early  The universe has too many large structures, to be created in 10-20 billion years. We know the rate of expansion, thus we can get a rough estimate on how long it would take for them to form.  It should take about 100 billion years for the universe to form considering the large structures in it. 3. New Theory (The space-time continuum) According to Albert Einstein, the universe is a space-time continuum: It could take one of three forms:-  Closed (looks like a sphere) Travel far enough and you always come back to the starting point.  The universe will slow down, stop, then reverse direction causing a new Big Bang.  Open universe (looks like a saddle) galaxies continue to expand forever  Scientist believe a flat universe : When traveling in a straight line you will never return to your starting point. This is the shape of our universe according to the latest observations.  Timing http://www.hayadan.org.il/BuildaGate4/portals/hayadan/imagesP/sub36/368744087-L-big-bang-theory.jpg  3 minutes after big bang The universe has grown from the size of an atom to larger than the size a grapefruit E=mc2 (according to Albert Einstein’s equation energy froze into matter). This basically says that like snowflakes freezing, energy forms matter into clumps that today we call protons, neutrons and electrons. These later form into atoms  Chemical Elements form About several hundred thousand years after Big Bang ATOMS form (specifically Hydrogen and its isotopes with a small amount of Helium.) The early Universe was about 75% Hydrogen and 25% Helium. It is still almost the same today. About 200 to 400 million years after Big Bang 1st stars and galaxies form  What is a Galaxy ? A Galaxy is a large assemblage of Stars, Gas and Dust that is held together by the mutual gravitational interaction between its constituents. Galaxies contain between a few million and about ten trillion stars together with differing proportions of interstellar matter (Gas & Dust) Spiral Galaxy NGC1512 Galaxy Formations ? 300,000 yr after 12 billion yr later the Big Bang The Center of the Milky Way Galaxy Optical satellite data The effect of dust  About 4.6 billion years ago Our Solar system forms  Earth Our Solar system forms Summary Big Bang Timeline Big Bang – energy Matter E=mc2 protons Neutrons electrons Atoms Hydrogen helium Stars and galaxies Our solar system Sun and all planets Earth (present day)  References  Foundations of Big Bang Cosmology:WMAP Cosmology 101: http://map.gsfc.nasa.gov/m_uni/uni_101bb2.html  Riodan,Michael and Zajc, William a. “The First Few Microseconds,” Scientific American: May 2006  Wikipedia:Big Bang Theory: www.wikipedia.org/big_bang/article  Thornton, Stephan T. and Rex, Andrew. Modern Physics for scientists and engineers, Thomson 2006