Light Speed Relativity: A Puzzling Question

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Discussion Overview

The discussion revolves around the nature of light speed in the context of special relativity, particularly focusing on a thought experiment involving a spaceship moving at 99.5% the speed of light. Participants explore how light behaves when emitted from within a moving frame of reference and the implications of time dilation and length contraction.

Discussion Character

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

Main Points Raised

  • One participant expresses uncertainty about their understanding of light speed, stating that it is a consistent rate and questioning how light would appear to travel within a fast-moving spaceship.
  • Another participant asserts that all observers will measure light traveling at the speed of light (c), regardless of their relative motion, attributing this to time dilation and length contraction.
  • A third participant provides external resources for further reading on the topic, suggesting that the question has been frequently discussed in the forum and on Wikipedia.
  • A later reply reiterates the initial question and emphasizes that both the observer inside the spaceship and a stationary observer outside would measure the light traveling at c, referencing the need to understand wave behavior and Lorentz transformations.

Areas of Agreement / Disagreement

Participants generally agree that light speed remains constant at c for all observers, but there is some uncertainty regarding the implications of this for the observer inside the spaceship. The discussion includes multiple viewpoints and does not reach a consensus on the participant's initial understanding.

Contextual Notes

Some limitations include the potential misunderstanding of relativistic effects, the need for clarity on how time dilation and length contraction specifically affect the perception of light speed, and the reliance on definitions of motion and reference frames.

Nel
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So let me first off say i probably have no idea what I am talking about. I am simply a junior in high school whos only knowledge of physics is that of what i try to research on my own time. I really do like it though.

But it is my understanding that light speed is a consistent rate and no matter how fast you are moving you can not increase the speed of light.

So here is the question:

If you were in a spaceship moving at 99.5% the speed of light from left to right and you turn on a light inside the cabin which made the light travel left to right. Would you be able to see the light go across the room in a like slow mode manner due to your speed is so close to that of light or would it be instant due to time relativity? or do i just not have a clue what I'm talking about?

(ps this is not homework)
 
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All observers will always measure light at c, regardless of their speed. Both the people on your ship and people that are stationary relative to it (Earth), would measure the light moving at the normal speed of light. It would be due to time dilation, and length contraction.
 
Nel said:
So let me first off say i probably have no idea what I am talking about. I am simply a junior in high school whos only knowledge of physics is that of what i try to research on my own time. I really do like it though.

But it is my understanding that light speed is a consistent rate and no matter how fast you are moving you can not increase the speed of light.

So here is the question:

If you were in a spaceship moving at 99.5% the speed of light from left to right and you turn on a light inside the cabin which made the light travel left to right. Would you be able to see the light go across the room in a like slow mode manner due to your speed is so close to that of light or would it be instant due to time relativity? or do i just not have a clue what I'm talking about?

(ps this is not homework)

It turns out that you'll measure the light to travel at c anyway, and so will someone standing outside the ship who is considered motionless. The reason is that you register, say, 1 tick on your clock and the motionless guy registers, say, 500 ticks. Read up on it, you need to learn about how waves (like sound) behave and about the Lorentz transformations.
 

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