Red or Blue Shift: Moving Light Sources Forward/Backward

In summary, the red or blue shift of electromagnetic waves depends on the relative velocity between the source and observer. This means that the shift will occur when the observer is moving away or towards the source, but not when the source itself is being moved forward or backward with the observer. The perception of "red" or "blue" light is not affected, but the analysis of the spectrum will show a shift in the location of the lines. The Doppler shifts apply regardless of whether the source is moving towards or away from the observer.
  • #1
lnsanity
34
0
I want to know if the red or blue shift apply if I am moving away or toward a light beam and if it still apply if I am moving the light beam source with me forward or backward.
 
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  • #2
That is the entire reason for red/blue shifts of electromagnetic waves. When one is stationary with respect to the galaxy or source of light in question, and that light is moving radially toward us or away the waves will be stretched or contracted depending on it's motion. This doesn't mean that perceptually you will see "red" light or "blue" light, but when analyzing the spectrum you can determine where the lines ought to be and where they actually are, shifted towards the blue or red end of the spectrum. The same stands for the light in your hand although you wouldn't be able to tell the difference due to the slow velocity with which you're moving the light source.
 
  • #3
lnsanity said:
I want to know if the red or blue shift apply if I am moving away or toward a light beam and if it still apply if I am moving the light beam source with me forward or backward.
The Doppler shifts depend only on the relative velocity between source and observer.
 
  • #4
clem said:
The Doppler shifts depend only on the relative velocity between source and observer.

So that mean it apply when I am moving away or toward a light beam but does not apply when I am moving the light beam source with me forward or backward right ?
 
  • #5
yes you´re right.
if the light source is moving towards you(or if you´re moving towards the light source if you will), the electromagnetic waves(visible light for instance) will be shifted towards blue.
if the light source is moving away from you, the electromagnetic waves will be shifted towards red.
 
  • #6
lnsanity said:
So that mean it apply when I am moving away or toward a light beam but does not apply when I am moving the light beam source with me forward or backward right ?
If there is no relative velocity, there is no Doppler shift.
 
  • #7
Andromeda Galaxy= moving towards us=blueshift
Sombrero Galaxy=moving away from us=redshift
 

1. What is red shift and blue shift?

Red and blue shift refer to the change in the wavelength of light emitted by a source as it moves towards or away from an observer. Red shift occurs when the source is moving away, causing the light waves to stretch and appear more redshifted. Blue shift occurs when the source is moving closer, causing the light waves to compress and appear more blueshifted.

2. How do you measure red shift or blue shift?

Red shift and blue shift can be measured using the Doppler effect, which is the change in frequency of a wave due to the relative motion between the source and observer. This can be observed through the change in the wavelength of light emitted by the source.

3. What causes red shift or blue shift?

The main cause of red shift or blue shift is the relative motion between the source and observer. This can occur due to the source moving towards or away from the observer, or due to the expansion of the universe in the case of red shift for distant sources.

4. How does red shift or blue shift relate to the speed of light?

Red shift and blue shift are directly related to the speed of light. As the source moves towards or away from the observer, the speed of light remains constant, but the wavelength changes, resulting in the observed shift in color.

5. What can red shift or blue shift tell us about the universe?

Red shift and blue shift can provide valuable information about the motion of objects in the universe and the expansion of the universe. They can also help determine the distance of objects and the rate of expansion of the universe, providing insight into the evolution of the universe.

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