Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Our Expanding Universe 8.8E Students are expected to research how scientific data are used as evidence to develop scientific theories to describe the origin of the universe. Part I: Scientific Theory 1. On a piece of notebook paper, draw a tree map with three stems. Label one stem as “Steady State Theory”, one as “Oscillating Universe Theory”, one as “Big Bang Theory”. 2. Read the following selection. Take notes from the reading about each theory and organize the information in a tree map. Expert Information: Since the beginning of time, people have tried to explain how the universe came to be. Several models explaining the origin of the universe have been proposed and scientists have attempted to find evidence either supporting or disproving these theories. There are three models that are supported by the scientific community. One model states that the universe has always looked about as it does now, and its overall composition does not change. This model avoids the idea of expansion and contraction, and states that as galaxies move apart, new matter is created in the empty space. This model is called the Steady State Theory. The second model states that when the universe began, all matter was located within a specific region of space. An explosion occurred, sending matter forcibly outward. This model, called the Oscillating-Universe Theory, suggests that the universe goes through periods of expansion and contraction. According to supporters of this theory, our universe is now in a period of expansion. A third model was proposed by Georges Lemaitre in 1926. The Big Bang Theory states that all matter in the universe originated in a central location. Then, about 15 billion years ago, this region exploded and matter was hurled outward from the site of the explosion. This expansion has continued ever since. There is no real scientific evidence to support either the Oscillating Universe Theory or the Steady State Theory, but observations have been made that support the ideas behind the Big Bang Theory. In 1924, a scientist named Edwin Hubble observed the light from stars with an instrument called a spectrograph. His observations of light showed that some stars were moving toward earth and others were moving away from earth. The term electromagnetic spectrum refers to the entire range of light radiation, and includes radio waves, infrared rays, ultraviolet rays, x-rays, and visible light, the light that we can see. Visible light makes up only a tiny part of the electromagnetic spectrum. When white light is shone through a prism, it separates out into the colors of the rainbow. This is called the visible spectrum, and demonstrates that white light is a mixture of all colors. Hubble was able to show that as a star comes toward Earth, its wavelengths of light are squeezed together. As a star moves away from Earth, its light wavelengths are stretched apart. This squeezing and stretching of light is an example of the Doppler Shift. When stars are moving towards Earth, their light waves compress near the blue end of the spectrum. This is called blue shift. When stars are moving away from Earth, light wavelengths compress toward the red end of the spectrum, which is called red shift. Because of Hubble’s observations, the Big Bang Theory is the theory most widely accepted by scientists today.