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04-03-2001, 10:47 AM
ALBERT EINSTEIN
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The scientific touchstones of the modern age--the Bomb, space travel, electronics, quantum physics--all bear his imprint
EINSTEIN'S THEORY OF RELATIVITY
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Relativity asserts that light always moves in a straight line through empty space, and always at the same speed in a vacuum, no matter what your vantage point. From these simple claims follow bizarre consequences that challenge common sense and our perception of reality--but have been verified repeatedly by experiments.
Relativity and Time
A moving clock runs slower than a stationary one from the perspective of a stationary observer
1 A man riding a moving train is timing a light beam that travels from ceiling to floor and back again. From his point of view, the light moves straight down and straight up.
2 Watching from trackside, Einstein sees the man, bulb and mirror moving sideways; the light traces a diagonal path as it goes. From Einstein's viewpoint, the light travels farther. But since the speed is always the same, that means the same event measured on his clock takes more time.
Relativity and Length
A moving object appears to shrink in the direction of motion, as seen by a stationary observer
1 The man now observes a light beam that travels the length of the train car. Knowing the speed of light and the travel time of the light beam, he can calculate the length of the train.
2 Because Einstein is not moving with the train, from his point of reference the rear of the train will be moving forward to meet the beam of light, making the light beam appear to be shorter. Because the speed of light is always the same, he will calculate the train's length to be shorter. Part of this effect is offset by the fact that his clock is moving faster, but part remains the train actually shrinks. As the train approaches the speed of light, its length shrinks to nearly zero.
Sources World Book Encyclopedia; Einstein for Beginners
GENERAL RELATIVITY
Space-Time Distortion
In general relativity, time is considered a dimension like height, width and depth, creating a four-dimensional universe called space-time. Einstein argued that gravity is really a warping of space-time, with the greatest distortions near the most massive objects. Because light travels in a straight line through the contours of space-time, a light beam will curve where space-time curves. This curving was first measured in 1919, vindicating Einstein's theory.
Source Ultimate Visual Dictionary of Science
---------------
The scientific touchstones of the modern age--the Bomb, space travel, electronics, quantum physics--all bear his imprint
EINSTEIN'S THEORY OF RELATIVITY
-------------------------------
Relativity asserts that light always moves in a straight line through empty space, and always at the same speed in a vacuum, no matter what your vantage point. From these simple claims follow bizarre consequences that challenge common sense and our perception of reality--but have been verified repeatedly by experiments.
Relativity and Time
A moving clock runs slower than a stationary one from the perspective of a stationary observer
1 A man riding a moving train is timing a light beam that travels from ceiling to floor and back again. From his point of view, the light moves straight down and straight up.
2 Watching from trackside, Einstein sees the man, bulb and mirror moving sideways; the light traces a diagonal path as it goes. From Einstein's viewpoint, the light travels farther. But since the speed is always the same, that means the same event measured on his clock takes more time.
Relativity and Length
A moving object appears to shrink in the direction of motion, as seen by a stationary observer
1 The man now observes a light beam that travels the length of the train car. Knowing the speed of light and the travel time of the light beam, he can calculate the length of the train.
2 Because Einstein is not moving with the train, from his point of reference the rear of the train will be moving forward to meet the beam of light, making the light beam appear to be shorter. Because the speed of light is always the same, he will calculate the train's length to be shorter. Part of this effect is offset by the fact that his clock is moving faster, but part remains the train actually shrinks. As the train approaches the speed of light, its length shrinks to nearly zero.
Sources World Book Encyclopedia; Einstein for Beginners
GENERAL RELATIVITY
Space-Time Distortion
In general relativity, time is considered a dimension like height, width and depth, creating a four-dimensional universe called space-time. Einstein argued that gravity is really a warping of space-time, with the greatest distortions near the most massive objects. Because light travels in a straight line through the contours of space-time, a light beam will curve where space-time curves. This curving was first measured in 1919, vindicating Einstein's theory.
Source Ultimate Visual Dictionary of Science