"Let's go back to first year science, using Scientific Method, prove the Big Bang Theory."
OK, we can start with the Hubble Redshift and work our way through a bunch of other predicted observations to the microwave background, including how it is anisotropic in a manner consistent with the Big Bang.
So what do we do after lunch?
Edward Hubble revealed that the radiation could be left over from the explosion, but without exact evidence, without being there personally, we cannot assume it as fact. He was seeing this with telescopes (granted highly advanced telescopes), though he did not have any of that particle with him to study up close. If the theory were true, we would most likely be able to find the same residue in our own solar system. If someoene were able to find it, it would answer a lot of questions, but we would still not be able to prove it as fact. We can say that it is because evidence tends to look at it that way, but without actual presence there, again it remains just a theory. Explain how it is anisotrophic? Also, still, doesn't mean we observed the big bang, we only observed what may or may not be the resulting explosion.
Alright, Hubble said the radiation was left over from the explosion because the particles looked anisotrophic. Anisotrophic in what way? What's anisotrophic, the background microwaves?