Why does time and space have to be relative?

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Homework Help Overview

The discussion revolves around the concept of relativity in physics, specifically focusing on the Lorentz transformation and its implications for time and length as relative quantities. Participants are questioning the necessity of relativity for both time and length, exploring whether it is possible to maintain absolute time while still adhering to the principles of light speed constancy across different reference frames.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants express curiosity about the possibility of constructing a mathematical transform that allows for absolute time while keeping the speed of light constant in different frames. They discuss the implications of simultaneity in measurements across inertial reference frames and question the sufficiency of alternative constructs that have been considered.

Discussion Status

The discussion is ongoing, with participants raising various interpretations and exploring the implications of their questions. References to previous discussions indicate that this topic has been examined in depth, but no consensus has been reached regarding the nature of time and length in relation to relativity.

Contextual Notes

Participants note that the measurement of distance requires simultaneous observations, which is a point of contention when considering different inertial reference frames. The discussion also references external threads for further context on the topic.

aaaa202
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The lorentz-transform shows that both length and time are relative concepts.
My question is: Why does both time and length have to be relative? Why can't you mathematically construct a transform which transforms your x' relative to x such that light has same speed in both the x and x' frame while still keeping time an absolute quantity?
 
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aaaa202 said:
The lorentz-transform shows that both length and time are relative concepts.
My question is: Why does both time and length have to be relative? Why can't you mathematically construct a transform which transforms your x' relative to x such that light has same speed in both the x and x' frame while still keeping time an absolute quantity?
Measurement of a distance requires simultaneous measurements of two different points in space. The reason distance measurements are not the same in all inertial reference frames (IFORs) is because observers in different IFORs do not agree on what is simultaneous.

AM
 
aaaa202 said:
The lorentz-transform shows that both length and time are relative concepts.
My question is: Why does both time and length have to be relative? Why can't you mathematically construct a transform which transforms your x' relative to x such that light has same speed in both the x and x' frame while still keeping time an absolute quantity?
You can, and it was considered, but that is not sufficient.
We discussed this in the recent (and still open) discussion thread here:
https://www.physicsforums.com/showthread.php?t=625509

This is specifically addressed in post #20 and following posts:
https://www.physicsforums.com/showthread.php?p=4036452
 
aaaa202 said:
The lorentz-transform shows that both length and time are relative concepts.
My question is: Why does both time and length have to be relative? Why can't you mathematically construct a transform which transforms your x' relative to x such that light has same speed in both the x and x' frame while still keeping time an absolute quantity?
Say event A is light being emitted from a flashlight and event B is the light entering your eye. In the rest frame, the distance between your eye and the flashlight is x, so the time it will take for the light to propagate from A to B is x/c, where c is the speed of light. In the moving frame, x' is the distance between the two events. If x' is different and you insist c remains the same, can the time interval between A and B remain unchanged?
 

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