which a quantum-critical point [4] to some other phase lies, and a good empirical case can be made that it is promoted by quantum critical fluctuations. Critical regions, once their basic physics is understood, are always easier to understand quantitatively than regions away from criticality. This is because scale-invariance of critical fluctuations guarantees that far fewer parameters are required to specify the fluctuation spectra than away from criticality and these parameters can be deduced from experiments with less ambiguity than away from critical points. On the other hand, it is important to point out that calculations of the frequency and momentum dependent fluctuations for interacting fermions are fraught with difficulties. Es- pecially misleading are calculations of such quantities in perturbative approximations such as the random phase or self-consistent random phase approximations or phenomenological calculations which do not respect sum-rules. The inadequacies of such calculations are ev- ident for the case of superfluid He 3 and in cases where the calculations of simple models such as the Hubbard model with such methods are contrasted with those from elaborate numerical methods. The general moral is that analytical methods must be always tempered in this problem by the constraints of obtaining normal state properties in qualitative and quantitative form from the same fluctuations. There is a class of problems where rather precise numerical results on a model can be compared with the experiments and where at the unitarity limit of scattering universal results, independent of the details of the model are expected. This is the problem of low density of fermions on a lattice (or without a lattice) with variable inter-particle short-range attractive interaction in the s-wave channel. Definitive results obtained [5] on this problem bear comparison with experiments on cold atoms realized in optical traps [6]. The results serve as useful anchor to the discussion of some of the more difficult problems discussed here. After this prologue, let us look at the field of action. In fig. (1), measured T$_{c}$ for classes of superconductors is plotted on one axis and the measured specific heat coefficient γ in the other. The black points refer to superconductors where T$_{c}$ is known primarily to be determined by e-ph interactions and the red points refer to the others. No direct correlation between the two quantities plotted is on the whole implied or discernible. The point of plotting γ together with T$_{c}$ in the figure is simply a way of providing a parameter which is undoubtedly of importance for T$_{c}$ within a given class of materials as a judicious reading of 6