How do we know this back ground is a relic of the big bang? How sensitive is the information held in the CMB to the age of the universe? (would a +billion yr, -billion yr) make much difference? did this back ground record gravity waves?
There doesn't seem to be any alternate explanation. The main determinate is the expansion volume, not the time. Specifically, if the universe had expanded to the same size as now, it wouldn't make any difference as to how long ago it was. Could be, but I've not seen any report of this.
fishtail, How do we know this back ground is a relic of the big bang? It was predicted by General Relativity and as our measurements get more precise they fit the predictions even more closely. How sensitive is the information held in the CMB to the age of the universe? (would a +billion yr, -billion yr) make much difference? As the universe expands and cools so does the CMB. The temperature fits what is predicted by GR. I believe a billion years would make a significant difference in what the temperature would be. did this back ground record gravity waves? We aren't capable of detecting gravity waves as of yet. Therefore, they aren't confirmed to exist. There is an experiment currently underway, and another more sensitive one in the works, so it is possible, in the near future, we may detect them. Since they too are predicted by GR, I believe they will be detected. Wilgory