darkfenrir
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- Dec 30, 2012
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- HSC
- 2013
I found it in a past exam, worth 8 marks, how much /8 would this get?
When Einstein was forming his theories on light and relativity, many of his postulates stemmed not from physical observations, but from thought experiments. One of these thought experiments involves a person travelling at the speed of light and looking at their reflection in a mirror.
Einstein’s question was whether the person would be able to see their own reflection. Under the aether model, light would travel at the same speed as the train and would never reach the mirror; hence the person would see no reflection. But this would violate the principle of relativity, as then it would be possible to detect the motion of the train within the inertial frame.
If the principle of relativity held, the person would be able to see their reflection, and hence the light in the frame would be travelling at the normal speed of light. But under Galilean relativity, an observer at rest outside the train would see light travelling at twice the speed of light.
Einstein believed that this would not occur, and instead both people would see light travel at the speed of light (3x108ms-1). Thus he postulated that the speed of light is constant in all frames of reference.
This postulate was based on logical thought, as the technological limitations of the time meant that Einstein had no way to physically measure his postulates. His thought experiments however allowed him to analyse and demonstrate his theory of relativity, even though they could not be tested in reality. From these thought experiments, Einstein was able to make deductions based on logic and fact to develop new theories, many of which have been proven physically correct since. Thus thought allows us to conduct hypothetical experiments using logic to gain a deeper scientific understanding, even if such experiments cannot be easily reproduced in reality.
When Einstein was forming his theories on light and relativity, many of his postulates stemmed not from physical observations, but from thought experiments. One of these thought experiments involves a person travelling at the speed of light and looking at their reflection in a mirror.
Einstein’s question was whether the person would be able to see their own reflection. Under the aether model, light would travel at the same speed as the train and would never reach the mirror; hence the person would see no reflection. But this would violate the principle of relativity, as then it would be possible to detect the motion of the train within the inertial frame.
If the principle of relativity held, the person would be able to see their reflection, and hence the light in the frame would be travelling at the normal speed of light. But under Galilean relativity, an observer at rest outside the train would see light travelling at twice the speed of light.
Einstein believed that this would not occur, and instead both people would see light travel at the speed of light (3x108ms-1). Thus he postulated that the speed of light is constant in all frames of reference.
This postulate was based on logical thought, as the technological limitations of the time meant that Einstein had no way to physically measure his postulates. His thought experiments however allowed him to analyse and demonstrate his theory of relativity, even though they could not be tested in reality. From these thought experiments, Einstein was able to make deductions based on logic and fact to develop new theories, many of which have been proven physically correct since. Thus thought allows us to conduct hypothetical experiments using logic to gain a deeper scientific understanding, even if such experiments cannot be easily reproduced in reality.
