From what I understand, red-shifting is when light from a distant source travels through expanding space which stretches out the wave making it appear more red by the time it reaches earth.
So if a light wave traveled far enough, would it “red-shift” all the way down the EM spectrum eventually losing its waviness and becoming a straight line?
In: Physics
There is no end to the EM spectrum. So it can keep being redshifted indefinitely.
There’s also a cap on how far light can go (based on the age of the universe).
The big example of this is the cosmic microwave background; this is the light that was emitted in the early stages of the universe – when the universe first stopped being opaque. This light has been redshifted (by universal expansion) as much as it is possible for any light to be redshifted, and it is currently microwave radiation (obviously), with a wavelength of around 1-2mm. Radio waves can work with wavelengths in the hundreds of kilometres. There is plenty of space for more redshifting.
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