Quantum Mechanical Tunneling Probability

[Demon117]

I recently took an exam in which the professor asked the following question:

Suppose an object of mass 2 grams were incident on a rectangular barrier of height 20 cm and width 2.0 cm. What is the probability that the object will quantum mechanically tunnel and appear on the other side?

I argued that since this object has a mass on the order of 10^27 times greater than the electron that qualitatively the probability would be negligible. Furthermore I argued that such a macroscopic object could be described classically so why would we describe such an object by a wave-function propagating in space? I'd like to hear your ideas on the matter and see what others say. Thanks!

 

[Bill_K]

I'd say that you're right, it's "negligible", but your professor probably wanted you to come up with a number. You have to play to the audience.

I'd also say that Schrödinger quantum mechanics is intended to describe a point particle, and treating a 2 gram object as if it were a point particle is pretty hokey. What if half the object penetrated the barrier and the other half did not?