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AOTANI, Masayasu
Edwin Hubble Changed Our Ideas About the Universe and Its Birth
Today the space telescope named for him helps astronomers carry on his work and make new discoveries. Transcript of radio broadcast:
28 November 2006
In the late nineteen twenties, Hubble studied the movement of galaxies through space. His investigation led to the most important astronomical discovery of the Twentieth century -- the expanding universe.
Earlier observations about the movement of galaxies had been done by V. M. Silpher. He discovered that galaxies are moving away from Earth at speeds between three hundred kilometers a second and one thousand eight hundred kilometers a second.
Hubble understood the importance of Silpher's findings. He developed a plan for measuring both the distance and speed of as many galaxies as possible. With his assistant at Mount Wilson, Milton Humason, Hubble measured the movement of galaxies. The two men did this by studying what Hubble called the "red shift." It also is known as the "Doppler effect."
The Doppler effect explains changes in the length of light waves or sound waves as they move toward you or away from you. Light waves from an object speeding away from you will stretch into longer wavelengths. They appear red. Light waves from an object speeding toward you will have shorter wavelengths. They appear blue.
Observations of forty-six galaxies showed Hubble that the galaxies were traveling away from Earth. The observations also showed that the speed was linked directly to the galaxies' distance from Earth. Hubble discovered that the farther away a galaxy is, the greater its speed. This scientific rule is called "Hubble's Law."
Hubble's discovery meant a major change in our idea of the universe.
The universe had not been quiet and unchanging since the beginning of time, as many people had thought. It was expanding. And that, Hubble said, meant it probably began with an explosion of unimaginable force. The explosion often is called "the big bang."
Hubble's work did not end with this discovery. He continued to examine galaxies. He continued to gain new knowledge about them. Astronomers from all over the world went to study with him.
Hubble left the Mount Wilson Observatory during World War Two. He did research for the United States War Department. He returned after the war. Then, he spent much of his time planning a new, much larger telescope in Southern California. The telescope was completed in nineteen forty-nine. It had a mirror five hundred centimeters across. It was named after astronomer George Ellery Hale.
Edwin Hubble was the first person to use the Hale Telescope. He died in nineteen fifty-three while preparing to spend four nights looking through the telescope at the sky.
Hubble's work led to new research on the birth of the universe. One astronomer said scientists have been filling in the details ever since. And, he said, there is a long way to go.
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