(I) The conventional wisdom is that it is a molecule's
specific shape that allows our noses to distinguish
between one smell and another. (II) But there is new
evidence that it is actually the frequency of a molecule's
vibration, a quantum effect, that is all-important.
(III) Most olfactory (smell) scientists believe that
receptors within our noses act like a lock that can only
be activated by a molecule of a specific shape – the
'key'. (IV) Molecules are collections of atoms that can be
thought of as being connected by springs that can
vibrate. (V) The trouble is, some molecules with different
shapes have similar smells.