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I understand that the universe is generally agreed to be expanding based on observations. What I have read is that space itself is expanding. My question is why does this expansion of space affect the spectra of light itself?

It has been observed countless time since Hubble that light from distant galaxies arrive to us with spectra shifted to longer wavelengths (red-shifted). If a wavelength of light is defined with a metric of spatial distance, then what is the significance of spatial distance itself increasing? Would not the expansion of space where our instruments of observing light also matter?

I also have trouble understanding how $c$ itself is affected if it is a function of distance when space itself is expanding. $c$ is also a function of time, but I have heard that time at a fixed location would not be affected by the expansion of space, but I am uncertain how time for moving objects are affected.

I understand that the universe is generally agreed to be expanding based on observations. What I have read is that space itself is expanding. My question is why does this expansion of space affect the spectra of light itself?

It has been observed countless time since Hubble that light from distant galaxies arrive to us with spectra shifted to longer wavelengths (red-shifted). If a wavelength of light is defined with a metric of spatial distance, then what is the significance of spatial distance itself increasing? Would not the expansion of space where our instruments of observing light also matter?

To add to my confusion on red-shifts, here is the Planck-Einstein relation:

$\lambda = \frac{hc}{E_{photon}}$

Wavelength is a function of $c$, but would this constant (distance over time metric) be affected if space dilates? The same rationale goes for time, but I have heard that time at a fixed location would not be affected by the expansion of space, but I am uncertain how time for moving objects are affected.

I understand that the universe is generally agreed to be expanding based on observations. What I have read is that space itself is expanding. My question is why does this expansion of space affect the spectral of light itself?

It has been observed countless time since Hubble that light from distant galaxies arrive to us with spectral shifted to longer wavelengths (red-shifted). If a wavelength of light is defined with a metric of spatial distance, then what is the significance of spatial distance itself increasing? Would not the expansion of space where our instruments of observing light also matter?

I also have trouble understanding how $c$ itself is affected if it is a function of distance when space itself is expanding. $c$ is also a function of time, but I have heard that time at a fixed location would not be affected by the expansion of space, but I am uncertain how time for moving objects are affected.

I understand that the universe is generally agreed to be expanding based on observations. What I have read is that space itself is expanding. My question is why does this expansion of space affect the spectra of light itself?

It has been observed countless time since Hubble that light from distant galaxies arrive to us with spectra shifted to longer wavelengths (red-shifted). If a wavelength of light is defined with a metric of spatial distance, then what is the significance of spatial distance itself increasing? Would not the expansion of space where our instruments of observing light also matter?

I also have trouble understanding how $c$ itself is affected if it is a function of distance when space itself is expanding. $c$ is also a function of time, but I have heard that time at a fixed location would not be affected by the expansion of space, but I am uncertain how time for moving objects are affected.