- #1
moe darklight
- 409
- 0
doppler effect / expanding universe . trouble uniting both concepts?
Ok, I think I understand both; I just don't understand their relationship.
As I understand the doppler effect, in short, its cause by the difference in velocity (movement through space).
And as I understand the expansion of the universe, it is space itself that is expanding— i.e, things aren't literally "moving away" from each other; it is the actual space between them that is expanding.
Here's my problem: if one of the ways we can detect the universe's expansion is the doppler effect (a star's red-shift)... why is this red-shift happening if the star isn't actually moving away from us— that is, if it is space itself that is expanding, then it is not moving away from us in the same sense that it would be if something was physically pushing it away from us through space, which I understand is a requirement of doppler effect
I'm a bit more comfortable now with equations and mathematical explanations than I used to be, in case they are needed for the explanation (though I'll admit some of the more complicated ones still scare the crap out of me ). I wish I had more time to read physics
![Big Grin :biggrin: :biggrin:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Ok, I think I understand both; I just don't understand their relationship.
As I understand the doppler effect, in short, its cause by the difference in velocity (movement through space).
And as I understand the expansion of the universe, it is space itself that is expanding— i.e, things aren't literally "moving away" from each other; it is the actual space between them that is expanding.
Here's my problem: if one of the ways we can detect the universe's expansion is the doppler effect (a star's red-shift)... why is this red-shift happening if the star isn't actually moving away from us— that is, if it is space itself that is expanding, then it is not moving away from us in the same sense that it would be if something was physically pushing it away from us through space, which I understand is a requirement of doppler effect
I'm a bit more comfortable now with equations and mathematical explanations than I used to be, in case they are needed for the explanation (though I'll admit some of the more complicated ones still scare the crap out of me ). I wish I had more time to read physics
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