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The Universe - Astronomer Edwin Hubble observed that distant galaxies were moving away from the Milky Way. - How did he know this and what did it mean??? The Doppler Effect Waves in front bunch up (short wavelength) Waves behind spreadout (long wavelength) Redshift and Blueshift - light travels as a wave – blue light has short wavelengths - red light has long wavelengths Redshift and Blueshift - the wavelength of light coming from galaxies all around is getting longer (towards the red wavelength of light) - galaxies are moving apart, but they themselves do not expand because of gravity How does this relate to the Universe? • Hubble found that most galaxies had redshifted (meaning…) • They are moving away from the observer • This means that the universe is expanding • In honour of this discovery: the first large space telescope was named after Hubble Big Bang Theory http://www.youtube.com/watch?v=Vtk8eO_1ieU - between 10 & 15 billion years ago, all the matter of the entire universe expanded outwards from one small extremely hot mass under tremendous pressure - the “beginning” (time zero) - what happened before this is not known QuickTime™ and a decompressor are needed to see this picture. Evidence for the Big Bang Theory In 1965, two scientists detected unexpected radiation coming from all directions in space that could be the remains of the enormous amount of energy that exploded outwards at the time of the Big Bang. The Big Bang Theory • Cosmologist observe that at some time in the distant past the universe was extremely compact, small and unimaginably dense. Modern satellites can look back in time almost to the very beginning (approx. 14 billion years • Most cosmologist believe the beginning occurred in the Big Bang The Supporting Evidence • Distance-Redshift relationship, Hubble Constant • Cosmic microwave background (CMB) radiation-radiation left over from the Big Bang – Initially the universe was very hot, filled with gamma rays at short wave lengths. As the universe expanded the wavelengths expanded from gamma rays to visible rays – Today astronomers observe that CMB radiation has a wavelength of 1.07 mm (the microwave spectrum) What does it mean? • A young universe-the images captured by the satellites COBE and WMAP show a young universe at about 0.002% its present age. At this time it was very small, yet from our point of view it seems a huge shell that surrounds us. We see it in all directions as red-shifted when in fact it was still really small The Images • COBE Blue is colder, yellow red is warmer • WMAP How does this make sense • The light from our Sun take 8 minutes to reach us-that means the sunlight we see existed 8 minutes ago • The closest star is 4 light-years away-that means we see star light as it was 4 years ago • The galaxies are 10 billion light years awayshowing us what the galaxy was 10 billion years ago • Remember-the universe formed 14 billion years ago The Large Hadron Collider (LHC) What Is It? The largest particle accelerator ever built. It will recreate conditions just after the Big Bang. http://www.youtube.com/watch?v=2jup2R9Jtnc http://www.youtube.com/watch?v=sxAxV7g3yf8 How Does It Work? Two proton beams will be steered by magnets in opposite directions around a circular tunnel at close to the speed of light. At designated points around the tunnel, the beams will cross paths. Why Was It Built? Scientists hope previously unseen particles will be discovered when the beams smash together. When Will the Experiment Happen? It has already taken two decades to get this far. Physicists may have to wait between five and 10 years before they get any significant results. Evidence for the Big Bang Theory Read the article on the Big Bang. Highlight main points. Write a few paragraphs explaining the Big Bang Theory IN YOUR OWN WORDS. Imagine you were explaining it to a 5th grade student, so try to simplify it as much as possible. Make sure use full sentences and paragraphs. Make sure your work is neat and organized. Watch your spelling and grammar. Explain the theory and the evidence to support it.