Chapt1 Relativity
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- impossibility of measuring the speed of the ether with
respect to the Earth and the faliure of the Galilean velocity
transformation equation in the case of light.
- Einstein proposed a theory that boldly removed these
difficulties and at the same time completely altered our
notion of space and time.
He based his special theory of relativity on two postulates:
Dr. Maha Torjman
Dr. Maha Torjman
Dr. Maha Torjman
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We restrict the discussion to the concepts of simultaneity,
time intervals, and lengths
This three of which are quite different in relativistic mehanics
from Newtonian mechanics .
1-3-1- Simultaneity and the Relativity of Time:
Einstein devised the following thught experiment to illustrate this Point :
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O concludes that, because of the motion of the vehicle, if the light is to hit the
mirror, it must leave the Laser at an angle with respect to the vertical direction.
Comparing Figure (a) with Figure(b) , we see that the Light must travel faster in
(b) than in (a).
Second postulate of the special theory of relativity : O and O/ must both
measure C for the speed of Light .
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The light travels farter in the frame of O so ( The time interval ∆t measured
by O is longer than the time interval ∆tp measured by O/ .
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This effect is known as time dilation .
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Using the right triangle shown in Figure ( 1.5.c) , the Pythagorean theorem gives :
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∆tp is called the proper time
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The Proper Length
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Dr. Maha Torjman
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Dr. Maha Torjman