Redshift Basics: What is the Redshift Phenomenon?

Click For Summary

Discussion Overview

The discussion centers around the phenomenon of redshift, exploring its definition, causes, and implications in astronomy. Participants discuss the Doppler effect, types of redshift, and the visibility of redshift in astronomical observations.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • Some participants explain that redshift occurs due to the Doppler effect, where light waves emitted by a source moving away from an observer are stretched, resulting in a shift towards the red end of the spectrum.
  • Others compare the redshift phenomenon to the change in pitch of a train horn as it passes, emphasizing that the same principle applies to light frequencies.
  • One participant outlines three types of redshift: Doppler redshift, gravitational redshift, and cosmological redshift, each with different causes.
  • There is a question about the visibility of redshift, with one participant suggesting that it is typically not observable in everyday life and is primarily seen in distant galaxies moving at high velocities.
  • Another participant mentions the need for specific tools to measure the wavelength of light from distant stars to observe redshift effectively.
  • A participant raises a separate question about the visibility of supernovae, noting their unpredictable nature and that they can be observed if they become bright enough.

Areas of Agreement / Disagreement

Participants generally agree on the basic principles of redshift and its relation to the Doppler effect, but there is no consensus on the visibility of redshift in everyday life or the predictability of supernovae.

Contextual Notes

Some assumptions about the relative velocities required for noticeable redshift and the tools needed for measurement are mentioned but not resolved. The discussion also touches on the unpredictability of supernova events.

Who May Find This Useful

This discussion may be useful for individuals interested in astronomy, particularly those curious about the concepts of redshift and supernovae.

Viper
Messages
54
Reaction score
0
Can anyone explain to me the red shift
 
Astronomy news on Phys.org
Red shift occurs as a result of the doppler effect. When a source that emits waves moves towards you the waves emitted by the object arrive earlier than they would if the object was not moving and therefore waves arrive closer together (light moves towards the blue end of the spectrum). If the source is moving away from you the waves get more stretched out (the light moves towards the red end of the spectrum).
 
You know how the pitch of a train horn changes as it passes you? Thats the doppler effect. Same effect for light just that higher frequencies are toward blue and lower ones toward red.
 
In astronomy, there are 3 kinds of redshift...
(1) Doppler (see above)
(2) Gravitational (from light climbing out of a strong gravity field)
(3) Cosmological (expanding space stretching light waves)
 
Is the red shift visible then and how do I go about seing it?
 
I don't think you can go about observing a shift in light in everyday life. It's observed from stars in distant galaxies moving away from us at very high velocities. you would probably need a relative velocity of around 0.10c so that the Doppler factor for EM waves, sqrt((c+u)/(c-u)) gives a noticeable shift in wavelength.
So unless you've got the tools to measure the wavelength of light received from far-away stars, and compare with what the true wavelength should be, you might have to settle for sound :smile:.
 
My other question is that I've heard a lot about stars going super nova, do you know when I can view these?
 
Last edited:
Originally posted by Viper
My other question is that I've heard a lot about stars going super nova, do you know when I can view these?
It doesn't happen very often and its not all that predictable - so if there is a good one you might be able to see it after reading about it in the newspaper. They're generally visible for a week or so if they get bright enough.
 

Similar threads

Undergrad Material source of the quasar redshift
  • · Replies 5 ·
Replies
5
Views
2K
High School What is the relative speed of two groups of quasars with different redshifts?
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Need help simplifying standard error formula for redshift
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Challenges to the Redshift Method and Hubble's Law
  • · Replies 5 ·
Replies
5
Views
3K
Undergrad Energy conservation in Doppler (NOT cosmological) redshifts?
  • · Replies 13 ·
Replies
13
Views
3K
Graduate How deep in a gravitational well are we?
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Cosmological Redshift and Expansion
  • · Replies 20 ·
Replies
20
Views
3K
High School Is There a Limit to How Much Light Can Be Stretched Out in a Black Hole?
  • · Replies 8 ·
Replies
8
Views
3K
High School Redshifts of nearby galaxies
  • · Replies 14 ·
Replies
14
Views
4K
Graduate Cosmological and doppler redshift
  • · Replies 2 ·
Replies
2
Views
2K