pdf warning
The earth is at the center of an expanding bubble of electromagnetic radiation.
The bubble, expanding at the speed of light, contains all of the man-made
electromagnetic transmissions of the earth - radio, TV, radar, and so on. In
theory, an alien civilization could receive these signals, and form their opinion
about the earth by analyzing them. To most people, it is quite discouraging to
think that some alien civilization would form their opinion of earth based upon
our situation comedies.
Upon a slightly deeper analysis, the conventional wisdom says: 'Aliens might
detect our TV signals, but at least they can't form their opinion of our civilization
from our TV transmissions. Decoding the transmission is so much harder
than detecting it that we don't need to worry about this.'
In this paper I argue that this view considerably underestimates the technologies
that aliens might employ.