Lecture1-2

Edward williams morley 1838 1923 was an american

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Unformatted text preview: at Trinity College, Dublin, was the first to suggest that an oscillaCng electric current would produce radio waves, laying the basis for wireless telegraphy. In 1892 FitzGerald suggested that the results of the Michelson- Morley experiment could be explained by the contracCon of a body along its its direcCon of moCon. Einstein 15 Speed of Light u༇  The speed of light (c) was the central quesCon that gave rise to the theory of relaCvity. u༇  The speed of light is very large compared to the speeds we experience, c=3.00X108 m/s. o  We have no physical intuiCon about speeds approaching c. u༇  We can however measure the speed of light with a rotaCng mirror. o  Light bounces off the mirror twice with a long distance in between o  A small deflecCon results The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. 16 In what frame is the speed of light c? u༇  The equaCons of EM were consistent if the speed of light is constant in one fixed frame . o  Physicists thought EM waves must propagate in some medium. o  Postulated the “ether” (aether). •  They thought, space is filled with “the ether” in which EM waves propagate at a fixed speed. •  Is there fricCon as planets move through the ether? o  Ether gave one fixed frame for EM. u༇  But experiments disagreed. u༇  And we would loose the symmetry found in Newton’s laws; “any inerCal frame”. 17 The Sun and Earth are Moving u༇  u༇  u༇  We should see some velocity of the ether just due to the moCon of the earth. It is likely that we would be moving with a much larger velocity. Even if the earth happens to be at rest in the summer, it must then be moving in the winter. o  MM set up to be sensiCve even to the moCon of the earth. 18 The Michelson- Morley Experiment Albert Abraham Michelson (1852- 1931) was a German- born U.S. physicist who established the speed of light as a fundamental constant. He received the 1907 Nobel Prize for Physics. In 1878 Michelson began work on the passion of his life, the measurement of the speed of light. His aoempt to measure the effect of the earth's velocity through the supposed ether laid the basis for the theo...
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This note was uploaded on 02/24/2014 for the course PHYS 2D taught by Professor Hirsch during the Winter '08 term at UCSD.

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