How Does Relativity Affect Time Measurement and Velocity Perception?

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Discussion Overview

The discussion revolves around the effects of relativity on time measurement and the perception of velocity, particularly through the example of a "light clock" and the implications of observing its motion from different frames of reference. The scope includes theoretical considerations and conceptual clarifications related to special relativity.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant describes a time measuring device using a ball moving up and down, noting that from a stationary observer's perspective, the ball's path appears slanted, leading to a longer travel time and a decrease in vertical velocity.
  • Another participant suggests that a "light clock" is a more appropriate example, emphasizing the constancy of the speed of light for all observers and how this affects time measurement.
  • Questions are raised about the correctness of the assumptions underlying these observations, particularly regarding time dilation and the speed of light.
  • Some participants inquire about historical perspectives on the concept of light and its behavior in moving frames, with one asserting that Einstein was the first to conceptualize the "light clock."
  • A later post asks whether it was possible to mathematically calculate the time and velocity of light on a slant path in a moving frame before the assumption of constant light speed was established.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the historical context of the light clock concept and the validity of assumptions in relativity. There is no consensus on the earlier thoughts about light behavior or the mathematical calculations related to light in moving frames.

Contextual Notes

Limitations include the dependence on definitions of velocity and time, as well as unresolved questions about the historical development of these ideas and the mathematical frameworks that could have been used prior to the establishment of relativity.

rajeshmarndi
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In relativity example , a time measuring device is shown in which a ball moves up and down.

This device is then placed in a moving frame and the motion of the ball is observed from the ground.

To an observer on the ground, the path followed by the ball will be a slant line. And therefore when it strike the top, it has to travel a greater distance and therefore it takes more time and the vertical velocity of the ball also decreases to the observer on the ground.
Which is the reason why time run slower in a moving frame.

My question why the vertical velocity of the ball decreases and the velocity of the ball on the path as observed by the observer on the ground doesn't change?

Plz correct where I'm wrong!
 
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rajeshmarndi said:
In relativity example , a time measuring device is shown in which a ball moves up and down.
Generally such a clock uses pulses of light instead of balls and is called a "light clock". (Analyzing the motion of balls would be more complicated.)

This device is then placed in a moving frame and the motion of the ball is observed from the ground.

To an observer on the ground, the path followed by the ball will be a slant line. And therefore when it strike the top, it has to travel a greater distance and therefore it takes more time and the vertical velocity of the ball also decreases to the observer on the ground.
Which is the reason why time run slower in a moving frame.

My question why the vertical velocity of the ball decreases and the velocity of the ball on the path as observed by the observer on the ground doesn't change?
With light pulses instead of balls we can apply one of the fundamental assumptions of special relativity: that the speed of light is the same for all observers. Given that the speed of light is the same for all observers, and that the observer watching the moving "light clock" sees the light travel a longer slanted path, that observer must measure a longer time for that pulse to travel back and forth.
 
How do we know that the assumption is correct.
Thanks for replying.
 
rajeshmarndi said:
How do we know that the assumption is correct.
One important way is to compare the predictions of that assumption--the various relativistic effects, such as time dilation--with the results of experiment. So far, so good! (See the FAQ at the top of this forum.)
 
what was the earlier thought on the observation of this moving frame and the path of the light pulse or its movement.
Just eager to know its earlier thoughts. Thanks
 
I believe that Einstein was the first to think about a "light clock", so there were no earlier thoughts. At least none recorded that I know of.
 
before the assumption that light speed is same for all observer.

when velocity of the moving frame and the velocity of the light were given
was it possible to calculate the time and velocity of the light on the slant path in the moving frame mathematically and not by experimenting.
 

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