What Happens to Light When a Flashlight Hits an Asteroid?

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    Asteroid Light
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Discussion Overview

The discussion revolves around the behavior of light emitted from a moving flashlight when it encounters an asteroid, particularly in the context of the theory of relativity. Participants explore concepts related to the speed of light, relativistic effects, and the implications of different reference frames.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether light emitted from a flashlight moving at half the speed of light would "resume" its speed relative to the flashlight after it stops moving when it hits an asteroid.
  • Another participant asserts that the theory of relativity indicates that time changes rather than velocity when considering different frames of reference.
  • A participant explains that light travels at speed c with respect to both the flashlight and the asteroid, noting that the frequency of light would differ based on the observer's motion, referencing the relativistic Doppler shift.
  • One participant emphasizes that all observers measure light to be traveling at c, regardless of their relative speeds, and cautions against confusing phrases that imply otherwise.
  • Another participant stresses the universality of the speed of light, asserting that it remains constant across all reference points and explaining how space and time adjust to maintain this constancy.
  • A participant expresses curiosity about how intervening events might lead to conflicting observations regarding the speed of light.

Areas of Agreement / Disagreement

Participants generally agree on the principle that the speed of light is constant across all reference frames, but there is disagreement regarding the implications of this principle in the context of the original question about the flashlight and asteroid.

Contextual Notes

Participants discuss the implications of relativistic effects, but there are unresolved assumptions regarding the nature of light's behavior in different reference frames and the interpretation of events occurring simultaneously.

Who May Find This Useful

This discussion may be of interest to those exploring concepts in relativity, the behavior of light in different reference frames, and the implications of relativistic effects in physics.

keepitmoving
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if a flashlight is moving at half the speed of light and sending out light at a relative speed of c and then the flashlight runs into an asteroid and wham, it stops moving relative to the asteroid, does the light that has already been sent out put on its retro rockets so that is can resume its speed at c relative to the smashed flashlight?
 
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That is the theory of relativity, time changes not velocity.
 
Light leaves the flashlight traveling at c, and it travels at c with respect to both the flashlight and asteroid. The main difference is measuring while traveling with the flashlight you would get one frequency and measuring with the asteroid you would get another higher frequency. This is called the relativistic Doppler shift.
 
keepitmoving said:
if a flashlight is moving at half the speed of light and sending out light at a relative speed of c and then the flashlight runs into an asteroid and wham, it stops moving relative to the asteroid, does the light that has already been sent out put on its retro rockets so that is can resume its speed at c relative to the smashed flashlight?

The main premise of relativity is that all obsevers measure light to be traveling at c no matter what their speed is relative to another observer. This doesn't change if an observer's speed changes. Phrases like the ones above will cause you confusion.
 
You have not grasped the idea that the speed of light is universal. This is VERY important to understanding relativity.

Simply put, light moves at c from all reference points. It does not matter if the flashlight was moving at .5c or .999999c or .0000000001c, light moves at c at all costs.

If you were racing with a beam of light, and you moved at .9999c, you would say that light is moving .0001 c faster than you right? Wrong. It is moving at c relative to you. You would wonder how is it possible that its moving at c relative to you even tho u are moving at .9999c...well that is because space and time change in order for light to remain at c from ANY reference point.
 
i always wondered about the possibility of intervening events as far as conflicting observations.
 

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