  We start by reviewing some interesting results in mesoscopic physics
illustrating nontrivial insights on Quantum Mechanics. We then review the
general principles of dephasing (sometimes called "decoherence") of
Quantum-Mechanical interference by coupling to the environment degrees of
freedom. A particular recent example of dephasing by a current-carrying
(nonequilibrium) system is then discussed in some detail. This system is itself
a manifestly Quantum Mechanical one and this is another illustration of
detection without the need for "classical observers" etc. We conclude by
describing briefly a recent problem having to do with the orbital magnetic
response of conduction electrons (another manifestly Quantum Mechanical
property): The magnetic response of a normal layer (N) coating a
superconducting cylinder (S). Some recent very intriguing experimental results
on a giant paramagnetic component of this response are explained using special
states in the normal layer. It is hoped that these discussions illustrate not
only the vitality and interest of mesoscopic physics\cite{book} but also its
extreme relevance to fundamental issues in Quantum Mechanics.
