Could "Redshift" not result from the Doppler effect? Redshift is the astronomical phenomenon where galaxies and other far-away objects appear shifted to the "red" side of the visible light spectrum. The farther an object is from us, the more pronounced this shift is. This phenomenon is most commonly attributed to the "Doppler" effect -- objects are moving away from us and the light they emit therefore appears shifted to lower frequencies. Therefore, we think that the farther an object is from is, the faster it is moving away from us! This is often cited as evidence that the universe is expanding. My question is: Is it possible that redshift is not due to the Doppler effect? In general, waves seem to be able to travel longer at lower frequencies. The most obvious example is sound -- we can hear thunder from far away, but not high-pitched noises. This also seems to be true for the electromagnetic spectrum (in which visible light resides). We can see light from far away stars, but it is very hard to detect the energy in the form of gamma rays and X-rays (which we can detect from the sun). We detect microwave radiation from places in the universe that are at much greater distances from where we can detect any visible light. Is it possible that redshift is simply a result of light at higher frequencies being absorbed, before it reaches us from very far objects? Thanks for humoring me!