How long would it take for a can of beer to fall over due to quantum tunneling?

lackrange

It's on page 4 (this isn't homework, just something I stumbled upon, it's also in Griffith's 8.17):http://www.physics.udel.edu/~msafron...cture%2018.pdf .
Can someone help me understand this solution? What exactly is happening...are there particles at h/2 that are smashing against the bottle trying to tip it over? What exactly is tunneling? The solution makes it seem as if it is the center of the bottle that might spontaneously jump up to the critical point and then tip over, but then I don't understand what the frequency of attempts is, why the product should necessarily be 1 (is that just an arbitrary estimate we use for how long it will take to fall over?), and more importantly, why we are setting E=0...they set the potential energy to be 0 at the center of the bottle, but what about kinetic energy?

lackrange

Bump. Any ideas at all would be great.