Lesson 1 OGT Schiff


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Lesson 1 OGT Schiff

  1. 1. Lesson 1 The Universe
  2. 2. The Big Bang Theory The most widely accepted theory for the formation of the universe is known as the big bang theory  According to this theory all matter was once compacted in a tiny, dense particle smaller than a piece of dust  The particle was compacted by extreme pressure and temperature until an explosive event called the big bang 
  3. 3. The Big Bang Theory Evidence suggests that the big bang occurred approximately 13.7 billion years ago  In a fraction of a second, this explosion propelled matter and energy outward in all directions, forming the universe  More than 300,000 years after the big bang, some of this matter cooled to form galaxies   Galaxies are very large groups of stars and associated matter that are found throughout the universe
  4. 4. Evidence for the Big Bang Scientists study the movement of galaxies to help understand how the universe formed  These studies show that most galaxies today are moving apart  This observation indicates that the universe continues to expand 
  5. 5. Evidence for the Big Bang       To understand how galaxies are moving look at the balloons to the right The balloon on the left is only partly inflated The dots on the balloons represent galaxies As more air is added to the balloon, it expands, as shown on the right As the balloon expands its “galaxies” move farther apart The movement of the galaxies on the balloon model is similar to the movement of galaxies observed by scientists Galaxies
  6. 6. Evidence for the Big Bang       After the explosion of the big bang, the matter and energy of the universe would have started moving outward in all directions Evidence for the motion of galaxies comes from the light they give off The light from most galaxies is shifted toward the red end of the spectrum This red shift indicates that the galaxies are moving away from Earth in all directions The red shift provides evidence that the universe is expanding In the 1920’s Edwin Hubble demonstrated that the farther away a galaxy is, the faster it is moving
  7. 7. Evidence for the Big Bang Additional evidence supporting the big bang theory was provided by the discovery of cosmic background radiation in the mid 1960’s  This weak radiation was found to be coming from all directions of space  The universe at the time of the big bang would have been very hot, and would have given off large amounts of infrared radiation (thermal energy) and visible light  As the universe has expanded, it has also cooled  The cosmic background radiation is thought 
  8. 8. Steady-State Theory Not all scientists agree with the big bang theory  They don’t accept that the universe had a definite beginning  Another theory for the formation of the universe is the steady-state theory  This theory proposes that the universe has always looked the same on a large scale  And the theory states that the universe looks the same in one location as it does in any other location 
  9. 9. Steady-State Theory Evidence that the universe is expanding seems to contradict the steady-state theory  However, proponents of the steady-state theory hypothesize that as the universe expands, new matter is created  In this way, the overall density of the universe stays the same 
  10. 10. The Future of the Universe Scientists use measurements from Earth to various galaxies to estimate the age of the universe and how it changes  Such measurements indicate that the rate of expansion of the universe is increasing  It is not clear whether the universe will continue to expand forever 
  11. 11. The Future of the Universe        Some scientists hypothesize that at some point in time, the expansion of the universe will slow down Some believe that as more matter forms, gravitational attractions between objects in space will prevent the universe from continuing to expand The pulsating universe theory suggests that once the universe stops expanding, it will begin to contract and collapse until it returns to its original state In other words, the events resulting from the big bang will take place in reverse until the universe contracts back to a single point in a big crunch Some scientists believe the universe will continue to expand forever Stars making up galaxies will age and die As more stars die over billions of years, the universe will eventually grow cold and dark