Imagine a 1-molecule thick layer of liquid, evenly dispersed across a perfectly flat surface. This surface is (for this thought experiment) impenetrable and sound does not pass through it; it is unable to resonate or vibrate. If we apply sound waves or some other frequency/wave generation to the liquid, what will happen? Will it experience peaks and valleys? If so, what will be "under" the peaks? What if this 1-molecule thick liquid is sandwiched between two of these impenetrable plates (that is, two plates 1 liquid-molecule's width apart, with this liquid in between them)? Can waves pass through the liquid? If so, how would they form and what would they look like? What if we have no liquid, but air in this space between the plates? Remember that the plates themselves do not resonate. Thanks!