- #1

Pelion

- 35

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- TL;DR Summary
- Two identical bodies are cooling at the same rate in frame S while an observer in frame S' has some explaining to do.......

Hi all,

Consider the situation depicted in the illustration. Two identical 'square plates' are situated at rest, in frame S, as shown: Plate A has its thickness 'a' parallel to the x-axis and its sides 'L' parallel to the y and z axes, while plate B has its thickness parallel to the y-axis and its sides parallel to the x and z axes. They are heated to the same temperature and then are accelerated until they attain a velocity 'v' along the x-axis with respect to an observer in frame S'. Now, in S', plate A will only have its thickness 'a' contracted while plate B will only have the side 'L' parallel to the x-axis contracted. This means that, for the observer in S', plates A and B have different total surface areas and, if we presume that a<<L and that v is in the relativistic range, this difference in total surface area will be dramatic. For the observer at rest with plates A and B, in frame S, the two plates will display the same temperature for all times as they cool (assuming, in this thought experiment, that we are in the vacuum of outer space and that outer space is homogeneous and isotropic). The identically dropping temperature readings, at all times, are an objective fact...how does the observer in S' explain this fact despite his perception of drastically different surface areas associated with plates A and B ??

Cheers...

Consider the situation depicted in the illustration. Two identical 'square plates' are situated at rest, in frame S, as shown: Plate A has its thickness 'a' parallel to the x-axis and its sides 'L' parallel to the y and z axes, while plate B has its thickness parallel to the y-axis and its sides parallel to the x and z axes. They are heated to the same temperature and then are accelerated until they attain a velocity 'v' along the x-axis with respect to an observer in frame S'. Now, in S', plate A will only have its thickness 'a' contracted while plate B will only have the side 'L' parallel to the x-axis contracted. This means that, for the observer in S', plates A and B have different total surface areas and, if we presume that a<<L and that v is in the relativistic range, this difference in total surface area will be dramatic. For the observer at rest with plates A and B, in frame S, the two plates will display the same temperature for all times as they cool (assuming, in this thought experiment, that we are in the vacuum of outer space and that outer space is homogeneous and isotropic). The identically dropping temperature readings, at all times, are an objective fact...how does the observer in S' explain this fact despite his perception of drastically different surface areas associated with plates A and B ??

Cheers...