PROFESSOR CIMA: I've got a little demo here.
I have to be careful not to touch it.
What you see here, if you can barely see it, is two pieces of
what's called PDMS.
Silicone.
It's the same stuff that you use to caulk windows, and-
we're not done yet.
There are two pieces, and when you put them on top of one
another, they stick.
But what makes them stick is this van der Waals or London dispersion force.
So even though it's r to the sixth dependence, this is what many
materials exhibit, this force, day to day.
And we'll talk more about that.