THE BIG BANG THEORY. WHO REMEMBERS DOPPLER SHIFT? The Doppler Effect is the perceived change in...

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Transcript of THE BIG BANG THEORY. WHO REMEMBERS DOPPLER SHIFT? The Doppler Effect is the perceived change in...

The big bang theory

The big bang theoryWho remembers Doppler shift?The Doppler Effect is the perceived change in wavelength of a wave that is emitted from a source that is moving away or toward an object.

Red ShiftWhen objects move away from us, they appear redWhen objects move toward us they appear blueObservations made in the early 1900s revealed that most of the galaxies we can see have Doppler shifts toward the red end of the spectrumThe light waves are being stretchedThe Earth and the source of light are moving away from each other

Hubbles LawEdwin Hubble wanted to explain why the galaxies appeared to be moving away from us.Hubble realized that dimmer galaxies were most likely farther away from us than were brighter galaxies.He tried to find a relationship between the distance to a galaxy and their red shift.He found that galaxies exhibiting the greatest red shift are the farthest awayGreater red shift = greater speedEdwin Hubble was an astronomer that discovered that the universe was expanding. He did this by using the red shift of the spectra of stars. He observed the light from the galaxies at different distances from earth. From this light he could determine that the farther something was from earth, the faster it seemed to be moving away.

5Hubbles LawGalaxies are retreating from us at a speed that is proportional to their distancei.e. the farther away galaxies are, the faster they are moving away from us

This means the universe is expanding!

The big Bang theory?

The big bang theoryThe Big Bang Theory says that once the entire universe was confined in a hot, dense, supermassive ball

Approximately 13.7 billion years ago, a violent explosion occurred, hurling the material in all directions

Everything in our universe came from that ballEvidence of the Big BangRed Shift Hubbles LawCosmic Background RadiationRadio signals from all over the universe, could be leftover from Big Bang (H-pg 848)

10More Evidence for the Big BangCosmic Microwave Background radiation (CMBs) : the existence of an isotropic radiation bath that permeates the entirety of the UniverseIn 1964, two young radioastronomers, Arno Penzias and Robert Wilson, accidentally discovered the CMB using a well-calibrated horn antenna.They were trying to determine what was causing static in telephone lines. They worked for Bell Telephone company. It was soon determined that :the radiation was diffuse, emanated uniformly from all directions in the sky, had a temperature of approximately 3 Kelvin (2.73K). Isotropic radiation has same intensity no matter what direction11Cosmic Radiation Background

Stephen Hawkins - Cosmic Background Radiation What happens at the end?Idea One:Universe expands foreverStars burn out, leaving many black holes and other matterIdea Two: Universe eventually starts contracting (coming back together)Galaxies collapse on each other forming the Big CrunchIdea Three: Steady State Theory proposes that the universe looks the same as it always has.Right now, astronomers believe that Idea One is most likely13Sourceshttp://school.discoveryeducation.com/curriculumcenter/universe/activity2.htmlhttp://aether.lbl.gov/www/science/cmb.htmlhttp://space.about.com/od/astronomybasics/a/Origin-Of-The-Universe.htm