Back in the early 60s (IIRC) Robert Dicke and Jim Peebles of Princeton predicted that the Universe should be awash with the echoes of the Big Bang and had started to look for evidence of such. It turned out that at about the same time Arno Penzias and Robert Wilson of Bell Labs had inadvertently stumbled across exactly what Dicke and Peebles were looking for…the Cosmic Microwave Background (CMB).
Dicke and Peebles had predicted that due to the Universe’s expansion the radiation they were looking for would be red shifted into the microwave range of the spectrum and sure enough that’s where it was.
What I don’t understand is why this energy is redshifted? The farther we look out into space the greater objects are redshifted (i.e. the further away an object is the faster it is receding from us). So far so good. However, shouldn’t the CMB be right here in our own back yard so to speak? If I were to hop on my handy-dandy Insta-Travel spaceship and fly to a galaxy 15 billion light years away and measured the CMB I would see exactly the same thing I see hear on earth (because I assume that one location in the Universe is basically indistiguishable from any other place in the grand scheme of things). If I point my antenna towards Earth I would see the CMB coming from there as much as I would pointing it in any other direction.
If that is true then isn’t the CMB right here next to earth as well as everywhere else? If so why would that radiation be redshifted? Given its close proximity to Earth I would think the redshifting would be negligible (except for being blue-shifted a bit in the direction of Earth’s movement and slightly red-shifted looking ‘backwards’ from where Earth had just been).
As usual I am clearly missing something here as the CMB is a very well measured phenomenon at this point. Any enlightenment would be appreciated.