Introduction

``A neutrino is not a big thing to be hit by.

``In fact it's hard to think of anything much smaller by which one could reasonably hope to be hit. And it's not as if being hit by neutrinos was in itself a particularly unusual event for something the size of the Earth. Far from it. It would be an unusual nanosecond in which the Earth was not hit by several billion passing neutinos.

``It all depends on what you mean by 'hit' of course, seeing as matter consists almost entirely of nothing at all. The chances of a neutrino actually hitting something as it travels through all this howling emptiness are roughly comparable to that of dropping a ball bearing at random from a cruising 747 and hitting, say, and egg sandwich.''

Douglas Adams, Mostly Harmless

Adams proposes that the probability of dropping the ball bearing and hitting the sandwich is comparable to the probability of a neutrino interacting as it flies through the Earth. Below is a quick order-of-magnitude assesment of this prediction, based on loose estimates. Surpising results are detailed below.

These computations were made in good faith, without any fudging or manipulation of estimates to achieve a desired result. This calculation is by no means exhaustive, but remains open to further attempts at refinement.