Speed of Light Dilation: Does Observer See Slower Beam?

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Discussion Overview

The discussion revolves around the effects of special relativity on the perception of light speed from different frames of reference, particularly focusing on whether an observer will perceive a light beam emitted from a fast-moving spaceship as traveling slower than light in their own frame of reference. The scope includes theoretical implications of special relativity and the interpretation of time dilation and simultaneity.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants assert that an observer will always measure light as traveling at speed c relative to themselves, which aligns with the postulates of relativity.
  • One participant references a science program that suggested light would appear to travel slower in the discussed scenario, expressing concern about the accuracy of such a claim.
  • Another participant reiterates that light will travel at speed c regardless of the time dilation experienced by the spaceship, mentioning additional concepts like length contraction and relativity of simultaneity.
  • It is noted that both the observer and the spaceship perceive each other's time as running slower, leading to a complex interplay of perspectives regarding who is "traveling fast."

Areas of Agreement / Disagreement

Participants express differing views on the perception of light speed in relation to time dilation, with some asserting that light speed remains constant while others reference alternative interpretations. The discussion remains unresolved with multiple competing views present.

Contextual Notes

There are limitations regarding the assumptions made about the frames of reference and the implications of time dilation and simultaneity, which are not fully explored in the discussion.

Zman
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I am interested to know if the following special relativity scenario is generally accepted in physics.

Consider a spaceship that is traveling close to the speed of light relative to some observer.
The time on the space shift will run more slowly than that of the observer.

If a light beam is emitted from the space ship, will the observer see the light beam travel more slowly than light in the same frame of reference as the observer?
 
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The observer will always measure the light as moving at c relative to himself. This is one of the two postulates of Relativity.
 
The reason I asked is that I was watching a science program on BBC1 'Bang goes the theory' last week and they stated that light would seem to go slower in the scenario mentioned.
I would have assumed that they would have had expert advisors and that such an error wouldn't have been broadcast to the nation.
 
Zman said:
Consider a spaceship that is traveling close to the speed of light relative to some observer.
The time on the space shift will run more slowly than that of the observer.

If a light beam is emitted from the space ship, will the observer see the light beam travel more slowly than light in the same frame of reference as the observer?
No, the light beam will travel at c. Don't forget, in addition to the time dilation there is also length contraction and relativity of simultaneity.
 
Consider a spaceship that is traveling close to the speed of light relative to some observer.
The time on the space shift will run more slowly than that of the observer.

The time of the observer as seen from the spaceship also appears to run slower. Each observes the other's time as running slower.
The only possible way to tell who might be traveling "fast" and whose time might be relatively slower is by who has felt the force from acceleration...and by appropriately comparing elapsed clock times..
 

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