Where Have All the Spacemen Gone? Speculations On the Fermi Paradox (Part 3)

Well, we're back, and I'm not even singing this time! When we last met we were examining some of the many possibilities that have been offered over the years to explain the Fermi Paradox-the puzzling fact that when we search the stars for signs of life we find none, despite the popular opinion that it must exist.

Specifically, we were focusing on our second solution, which in general terms says that aliens are either uninterested in space travel and contact or are hiding from us. The three possibilities that we discussed were: the high cost of colonization; a lack of interest; and a lack of stamina. In this installment, we tackle three more:

1) We are being quietly observed.
2) Ethics get in the way.
3) A barrier could prevent our contact with others.

Let's jump right in.

THE ONE-WAY MIRROR
There is a rather popular solution to the Fermi Paradox that supposes that aliens