So i came to know that electrons residing across a tiny shell around fermi momentum takes part into the game of forming cooper pair but this phenomenon in real space is actually different. here all the electrons are taking part into this. what does it mean. i am not able to comprehend this physically. Also I have just started to read these so don't know much. But one thing i AM short of worried about why cooper pairs themselves don't scatter and contribute to resistivity. Is it because they are like bosons So that they just can pass through each other effectively(what i mean here is two fermions as a hole can be thought of as bosons I think at least theoretically two fermi operators does commute with other two).. Also why should not they get affected by impurities that is not clear to me as well. if someone physically try to motivate this that would be helpful,since algebra is fairly simple at this level but physical picture is somewhat obscure.