Most Scientists Believe:
•The universe is finite and expanding. •All matter, energy, and space was once squeezed into a very small volume. •This resulted in a sudden expansion known as the Big Bang. •The name is misleading because it was not an explosion as we think of an explosion. •Occurred 13.7 billion years ago •Galaxies expand throughout the universe like raisins baked in a cake. •They become more distant from each other as the cake rises. •It’s the cake (space) that is expanding causing the raisins (galaxies) to move. Important Theories •Albert Einstein’s General Theory of Relativity and Sir Isaac Newton’s original Theory of Gravity concluded the universe was static (lacking movement). •This was later proved untrue and Einstein would call it his “biggest blunder.” Edwin Hubble •1929 – Discovered an electromagnetic property called the Red Shift •Explained why galaxies appear to be accelerating away from the each other •Contrary to Einstein the Universe was expanding Red Shift •Think of the Doppler Effect when a fire truck passes. •The sound waves are compressed in front of the train and make a high frequency sound. •After the fire truck passes, the wavelengths spread out making a low frequency sound. •Light emitted from a star or galaxy can be separated into a band of colors, called a spectrum. •Each color has a different wavelength just like sound has wavelengths. •Notice the longer wavelengths are toward the red end of the spectrum. •Light behaves like sound. •Just like sound, light has “pitch”. •The red end of the spectrum has a lower pitch, or frequency, than the blue end. •Think of it in sound terms, red colors are the low notes and blue colors are the high notes. •If a star is moving away from us, the light gets stretched out. •This makes it appear more red than it really is. •If a star is moving toward us, the light gets squeezed. •This makes it appear more blue than it really is. •This shift in the absorption lines of galaxies lead Hubble to conclude that the galaxies are moving apart from each other. •Space is actually expanding causing the galaxies to move with it. •First piece of evidence supporting the BBT Cosmic Microwave Background Radiation (CMB) •Scientists thought if there was a BB, then there must be remnants of energy left out there in the far reaches of the universe. •This energy was found in the form of microwaves and is coming at us from every point in the universe. •It was called “relic” radiation. •In the mid 1960’s, and totally by accident, two young scientists picked up mysterious microwave static coming from every direction in the sky. •This radiation was very cold, which was expected. •They concluded it must be the “afterglow” of the BB. •This is the second piece of evidence supporting the BBT. Hydrogen and Helium •Using powerful telescopes, scientists have concluded the universe consists of mainly hydrogen (74%) and helium (25%). •These are the lightest elements. Heavier elements make up the other 1%. •This continuity throughout the universe supports the BBT. •Third piece of supporting evidence for the BBT Fred Hoyle •English astronomer, Fred Hoyle, coined the phrase Big Bang in 1949. •Most scientists consider it to be the most likely scenario for the birth of the universe. •There is much more supporting evidence, which is not included in this lesson. Comments are closed.
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Erik E. Mason
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