Did you ever wonder … How the earth or even the universe came to exist? Before… After… Lets start our investigation Observation: Red Shift When we looked (observation) at galaxies beyond our very own Milky Way and measured the wavelength of light, we realized that it was redshifted. This happens to waves that move away from us (the observer). This is just like what happens to the sound of a siren when it moves away from you. Red Shift What does that mean? If you look all around you and you see everything in the universe moving away from you, what do you think that means? Hmmm. I wonder… Developing Hypothesis Everything around us is moving away! So it seems the universe is expanding. The universe could have started out small then got bigger and we inside it look at all the things around as moving away. The theory that we accept to explain how the universe originated is called The Big Bang. According to Big Bang Theory, the universe as we know it today and everything in it started out as an unimaginably dense dot. Big Expansion In a fraction of a second the universe expanded from a tiny point to billions of light years wide and it released a lot of energy in the form of light. Whoaaa! Prediction Using the Big Bang theory, Ralph Alpher, Robert Herman, and George Gamow predicted that we should see this light as some sort of Cosmic Microwave Background uniformly (evenly) throughout the universe. How would you write this prediction in an If then statement? IF the Big Bang Theory were true and the universe suddenly expanded and released energy, THEN we should see an even distribution energy throughout the universe. Problem We didn’t know how to find it. Man this is tough. Annoying or Amazing? In 1964 two radio astronomers Arno Penzias and Robert Wilson working in Bell Labs in Murrey Hill, NJ detected this annoying “noise” in their data. They went through many tests to try to find the source of the noise. Interpret Observation They looked all around the sky and collected light in the radio and microwave range. They mapped what they collected and this is the “noise” they found. Describe what you observe. Supporting Evidence! Later scientists from Princeton realized that this “noise” found by Penzias and Wilson was predicted 16 years before using the Big Bang Theory! We found strong supporting evidence! Recap We observed red-shift of light form galaxies beyond ours. We hypothesized that the universe is expanding. We developed our hypothesis into the Big Bang Theory. It explains how the universe started and how it is expanding. We think that in during the initial expansion, a lot of energy in the form of light was released. Recap Continued We used the Big Bang Theory to predict that we should see an even distribution of light throughout the universe. We called this the Cosmic Microwave Background. We observed what we expected to observe thus supporting the theory. HOORAY! Big Bang Theory Lets learn more about the Big Bang Theory. The universe was a dot then it expanded then subatomic particles such as protons, neutrons, and electrons formed. Then The Universe Started to Cool After the initial expansion, the Universe started to cool. What do you think happened to the subatomic particles? (Hint: Think about water vapor when it cools.) QuickTime™ and a decompressor are needed to see this picture. Recombination The subatomic particles move slower so they don’t bounce off each other as violently giving them enough time to pull on each other and formed hydrogen atoms. Then these atoms cool more and formed clouds. A Star is Born These clouds of atoms are called Nebulas. They form through gravitational interactions. Nebulas are where stars are born. Like this one Inside Stars The more and more atoms get pulled towards the center due to gravitational interactions. At the same time bouncing off of each other creating lots of pressure. What do you imagine it would feel like to be at the center of a star? Fusion When there’s enough pressure in the center, two hydrogen atoms fuse forming 1 heavier atom, helium. 1 proton 2 protons 1 proton During the fusion process, light is emitted. When there is fusion in the big ball of gas, it becomes a star. Kaboom! If the star were very massive, At some point, it can no longer go through fusion. When it does, the star can no longer support itself and so it collapses inward causing a huge explosion called a Supernova. QuickTime™ and a decompressor are needed to see this picture. Forming Heavier Elements QuickTime™ and a decompressor are needed to see this picture. We are just star dust The remains of the supernovas create new nebulas as they cool off and then create more stars and “solar” nebulas. 5 Billion years ago, our sun was born, and soon after, our home, the Earth. QuickTime™ and a decompressor are needed to see this picture.
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