Microwave BG vs Expansion vs Hydrogen Microwave Emission

Good question. Assuming the cosmic background radiation is coming from the temperature of hydrogen gas within the last billion years, we would expect to see it gathered around visible galaxies. This is not the case, as the cosmic background radiation is nearly uniform in every direction. Furthermore, the intensity of the cosmic background radiation at 2.725 kelvin happens to fit perfectly with the big bang theory's prediction!

Another way of answering you is to say that the cosmic background radiation IS being attributed to BOTH "the big bang" and to "the emission from excited hydrogen". You see, about half a million years after the big bang, the universe had cooled enough for it to be transparent to light. When this happened, photons generated by hot hydrogen ions (read: protons) were created in abundance. These photons are still out there to this day, on their long journey to end up in one of our telescopes.

 

CMB are located everywhere. Compare with the CNB (Cosmic neutrino background).

Big bang happened everywhere, there are MANY threads on this fourm that deals with that question "where did big bang occur?", "where is the centre of the universe" and so on.

 

That's a plot of the microwave background in galactic coordinates.

Well, no, since the satellites that measure it are not on the earth.

There is no "point of the big bang". This is a common misconception of the big bang theory: there is neither a centre of the universe, nor a point at which the big bang happened.

Note that I have moved this to the Cosmology forum.

 

Another way of answering you is to say that the cosmic background radiation IS being attributed to BOTH "the big bang" and to "the emission from excited hydrogen".

If we were in a static universe we would see radiation from all the matter around us at whatever the average temperature was, say 2.7 kelvin (maybe this is not correct?). There must be some difference between that black body radiation and the big bang radiation, otherwise people would not have been so startled by the discovery. How would/did/do they differ? I realize that we are demonstrably not in a static universe, but I'm not sure it was such a secure fact when the CMB was first discovered. Something about it got everybody's attention, but I've never understood exactly what it was.