Understanding Redshift: Mathias' 15-Year-Old Query

[MathiasArendru]

Hello guys!

I know what redshift is and all concerning it, so i have a good understanding of it. Though there is something that my 15 year old little head can't really seem to understand... When a star emits its photon, it travels to us and due to the accelerating distance between it and us, the light is redshifted because it has to strech out its wave and therefore the wavelengt increases. To me, for this to make sence, the photon would have to have a set amount of frequences associated with it in the moment it gets emitted, and therefore the wavelength has to get streched out.

For example the first light year this light beam travels, it has a frequency and wavelength. When this photon has traveled the distance that was between the star and us, the moment it was emitted, it haven't reached us due to expansion. But at this point it still has the same frequency and wavelength. But when it then travels further and reaches us, it is redshifted or streched out sort of. What makes this happen!? Why doesn't it just continue with its frequency and wavelength.

I know I am going to get some responses saying that i should try not to think of it as either a photon or a wave, and i have no matter what i imagine i don't see why this has to happen.

Thanks in advance, Mathias

 

[Bandersnatch]

When this photon has traveled the distance that was between the star and us, the moment it was emitted, it haven't reached us due to expansion. But at this point it still has the same frequency and wavelength.

This isn't what happens.

The wavelength gets stretched continually as the light travels - by 1/144th of a percent per million light-years, iirc. Every bit of distance it covers adds a bit to its wavelength(therefore reducing frequency). It's as if the space was being stretched underneath, similar to a guitar string getting longer as you move your fingers up the instrument's neck - the standing wave in the string gets longer with it, producing lower frequency sounds.