Speed of Light & Red Shift: My Understanding

Click For Summary

Discussion Overview

The discussion revolves around the nature of light speed and the phenomenon of redshift, exploring the implications of measuring light speed in different contexts and the reasons behind observed redshift. The scope includes conceptual understanding and technical reasoning related to physics.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants assert that light always travels at a constant speed, regardless of the observer's motion.
  • One participant clarifies that redshift refers to a change in the frequency of light rather than a change in its speed.
  • Another participant explains that redshift occurs because it takes longer for a wave pulse to reach an observer if the observer is moving away from the source of the light.
  • Questions are raised about how light speed is measured and the implications of the observer's motion on this measurement.
  • There is a suggestion that the observed redshift may be related to the motion of the light-emitting object or the observer's motion away from it.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between light speed and redshift, with no consensus reached on the implications of these concepts.

Contextual Notes

Participants highlight the need for clarity on how light speed is measured and the conditions under which redshift is observed, indicating that assumptions about motion and observation may affect interpretations.

Who May Find This Useful

This discussion may be of interest to those studying the principles of light, redshift phenomena, and the implications of motion on measurements in physics.

TerryHM
Messages
7
Reaction score
0
My basic understanding is that no matter how you observe light, it always a constant, it always travels at the speed of light.

So even traveling at near the speed of light you will always measure light traveling at the speed of light. If this is the case? Why do we observe red shift?
 
Physics news on Phys.org
A redshift is a change in the frequency of the light, not the speed of light. I'm not sure what your concern is?
 
We observe redshift, because it takes more time for a long wave pulse to pass us, if we are fleeing the pulse.

If we want to know the speed of that wave pulse, we must measure how long it takes for one point on that wave pulse to pass us.

speed = length of observer / time it takes for the middle point of the wave pulse to pass the observer
 
Last edited:
TerryHM said:
My basic understanding is that no matter how you observe light, it always a constant, it always travels at the speed of light.
I'm genuinely curious: what is your understanding of how you observe light?

TerryHM said:
So even traveling at near the speed of light you will always measure light traveling at the speed of light.
I'm curious about this too: how do you measure how fast light travels?

TerryHM said:
If this is the case?
It depends on your answers to my previous two questions.

TerryHM said:
Why do we observe red shift?
Because the object that was emitting the light was moving away from us when the light started traveling towards us and/or because we are moving away from it when the light reached us. Do you think this question is related to your previous comments?
 

Similar threads

  • · Replies 19 ·
Replies
19
Views
2K
  • · Replies 46 ·
2
Replies
46
Views
5K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 26 ·
Replies
26
Views
966
  • · Replies 93 ·
4
Replies
93
Views
6K
  • · Replies 5 ·
Replies
5
Views
562
  • · Replies 72 ·
3
Replies
72
Views
5K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 25 ·
Replies
25
Views
2K
  • · Replies 34 ·
2
Replies
34
Views
6K