Question about the effect of c on light

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Discussion Overview

The discussion revolves around the effects of traveling at the speed of light on the perception and behavior of light beams, particularly in the context of special relativity. Participants explore hypothetical scenarios involving light and reference frames, touching on concepts such as black holes and the speed of light in different mediums.

Discussion Character

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

Main Points Raised

  • One participant questions whether traveling at the speed of light would cause a light beam to become matter from their frame of reference or if it would continue to move away at the speed of light.
  • Another participant references Einstein's conclusion that one cannot catch up with light, asserting that light is always observed at the same speed regardless of the observer's motion.
  • A participant proposes a scenario involving falling into a black hole with a flashlight, questioning if the flashlight would still function and emit light at the speed of light.
  • There is a discussion about whether light would still approach an observer traveling away from the light source at the speed of light, with some asserting that light will always approach at speed c.
  • One participant emphasizes that one cannot travel at the speed of light but can only approach it, while still affirming that light will always be measured at speed c by any observer.
  • Another participant introduces the concept of the refractive index (n) in a medium, noting that light travels slower than c in such mediums and mentioning phenomena like Cherenkov radiation.
  • There is a reiteration of the idea that regardless of the observer's speed, the speed of light remains constant at c, due to the effects of time dilation in different reference frames.

Areas of Agreement / Disagreement

Participants express a mix of agreement and disagreement regarding the implications of traveling at the speed of light and the behavior of light in various scenarios. While some concepts are clarified, there remains uncertainty and debate over the interpretations of these relativistic effects.

Contextual Notes

Limitations include the assumption that the speed of light is constant across all frames of reference, as well as the complexities introduced by relativistic effects that are not fully resolved in the discussion.

crapola77
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hi i have a loose knowledge of physics and was wondering if anyone could help me with a question i have... IF one was able to travel the speed light, in the same orientation of a beam of light, would that light beam become matter from your frame of reference? or would it speed away from you at 186 million miles an hour?
 
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IF one was able to travel the speed light,

That's the question Einstein asked himself at age 16.
At about age 26 he had the answer: The special theory of relativity: you cannot catch up with light. No matter how fast you move, light is still always observed at the same "c". It's one of the strangest classical phenomena, not at all intuitive, but has been experimentally verified with great accuracy.
 
got it, so let's say the sun collapses into a black hole in a couple minutes and i begin to fall into it with a flashlight, my flashlight still works?
 
or rather if i fall backwards into the black hole at nearly the speed of light,or even the speed of light, my flashlight still sends a beam of light away from me at c?
 
crapola77 said:
got it, so let's say the sun collapses into a black hole in a couple minutes and i begin to fall into it with a flashlight, my flashlight still works?
Yes. No matter what fraction of the speed of light you achieve with respect to some external reference point, you will experience nothing untoward happen to your flashlight. Light will leave it at the speed of light.
 
ok, so if your external frame of reference by which you measure your speed to be c is let's say a star of a beam light, does the light which travels toward your eyes still travel toward you at the speed of light, despite the fact that you measure yourself traveling away from the light source at the speed of light
 
crapola77 said:
ok, so if your external frame of reference by which you measure your speed to be c is let's say a star of a beam light, does the light which travels toward your eyes still travel toward you at the speed of light, despite the fact that you measure yourself traveling away from the light source at the speed of light

You cannot travel at the speed of light. You can only approach arbitrarily closely.

But yes, the beam of light will approach you at the speed of light.
 
DaveC426913 said:
You cannot travel at the speed of light. You can only approach arbitrarily closely.

ok ok but not considering that, because the fact that you can't subtract your velocity from light's at all seams to be the point, if you travel even 1mi an hr away from light it does not take the effect of allowing you to measure the speed of light going 1mi an hour less than it did when you were at rest. i assume its impossible to add you velocity with light's as well, which is to say if you travel at the speed of light towards a light source its light still travelstowards you at c
 
crapola77 said:
hi i have a loose knowledge of physics and was wondering if anyone could help me with a question i have... IF one was able to travel the speed light, in the same orientation of a beam of light, would that light beam become matter from your frame of reference? or would it speed away from you at 186 million miles an hour?

In fact, in a transparent medium with n>1 the light travels with v<c, and there are particles faster than that (charged particles radiate the Cherenkov's radiation, neutral ones do not radiate).
 
  • #10
whats n, sorry
 
  • #11
crapola77 said:
whats n, sorry

N is the medium refraction index. Used in the Snell equation, for example.
 
  • #12
crapola77 said:
ok ok but not considering that, because the fact that you can't subtract your velocity from light's at all seams to be the point, if you travel even 1mi an hr away from light it does not take the effect of allowing you to measure the speed of light going 1mi an hour less than it did when you were at rest. i assume its impossible to add you velocity with light's as well, which is to say if you travel at the speed of light towards a light source its light still travelstowards you at c

Whether you move away/toward the source of the light at 1 mile per hour or 669 million miles per hour, you will measure the speed of the light form the source at c.

The reason this is possible is that time passes differently in the two reference frames. At 99.9% of the speed of light, your frame of reference is basically slowed down by 99.9% (an over simplification) so that the light is still measured by you as c.
 

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