I think most of us are quite aware of Archimedes principle, but is there a reason to why it occurs? Is it just an observed property? Why is the upthrust equal to the weight of the liquid?

Phonons behave like Bosons, so they have a Bose Einstein distribution. If you take the zero temperature limit, the distribution vanishes. So at zero temperature there are basically no phonons (up to quantum fluctuations?). But to build a Cooper Pair in the BCS Theory you need phonons, the electro...