1. why, instead of cooper pair, don't we have a group of N electrons coupled for superconductivity? 2. Has cooper pair been observed experimentally? 3. What kind of thermometer do we used to measure near 0 K temperature? 4. Has Josephson tuneling for oxyde high Tc been made? Because there was a paper (I think from Bell's Lab) which claimed so? What is the potential technology to make a few angstrom thick of insulator? thank you.