Speed of Light & Red Shift: My Understanding

In summary, the conversation discusses the concept of redshift and its relationship to the speed of light. The speakers also mention the importance of understanding how light is observed and measured in determining its speed. They also bring up the question of why redshift occurs and how it relates to the movement of objects emitting light.
  • #1
TerryHM
7
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?
 
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  • #2
A redshift is a change in the frequency of the light, not the speed of light. I'm not sure what your concern is?
 
  • #3
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
 
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  • #4
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?
 
  • #5


Your basic understanding is correct - the speed of light is a fundamental constant and it always travels at the same speed regardless of the observer's frame of reference. However, the phenomenon of red shift is not caused by the speed of light changing, but rather by the expansion of the universe.

As the universe expands, the space between objects also expands, causing the wavelength of light to stretch out. This stretching of the light's wavelength is what we observe as red shift. It is similar to how the pitch of a siren changes as it moves away from you - the sound waves are stretched out and the pitch appears lower.

In the case of light, the stretching of the wavelength causes the light to appear more red, hence the term "red shift". This is an important tool in astronomy as it allows us to measure the distance and speed of objects in the universe.

So while the speed of light remains constant, the stretching of its wavelength due to the expansion of the universe can cause it to appear as if it is traveling at a different speed. This is why we observe red shift in distant galaxies and stars.
 

1. What is the speed of light?

The speed of light is a fundamental physical constant that represents the maximum speed at which energy, information, and matter can travel in the universe. It is denoted by the letter "c" and has a value of approximately 299,792,458 meters per second in a vacuum.

2. How is the speed of light measured?

The speed of light can be measured using various methods, including the time it takes for light to travel a known distance, the frequency of light waves, and the energy of photons. One of the most accurate techniques is the use of interferometry, which involves splitting a beam of light and measuring the time it takes for the two beams to recombine.

3. What is red shift?

Red shift is a phenomenon in which light from a distant object appears to have a longer wavelength (shifted towards the red end of the spectrum) than when it was emitted. This is caused by the expansion of the universe, which stretches the wavelength of the light as it travels through space.

4. How is red shift related to the speed of light?

The speed of light is directly related to red shift because as the universe expands, the light from distant objects has to travel a longer distance to reach us. This results in the light being stretched, causing its wavelength to appear longer and its frequency to appear lower, which is known as red shift.

5. What does red shift tell us about the universe?

Red shift provides evidence for the expanding universe and supports the Big Bang theory. It also allows us to estimate the distance of distant objects and measure the rate of expansion of the universe. Additionally, the amount of red shift can give us clues about the age and composition of the objects emitting the light.

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