God's Billboard, or is it pop-up?

Hmmm . . . (from the e-printed archives)

Suppose some superior Being or Beings got the universe going. We do not address the issue of whether or not this is likely, but merely proceed with this supposition. Furthermore, suppose that they actually wanted to notify us that the universe was intentionally created. The question we would like to ask is: How would they send us a message? . . .

In the United States, people with certain religious convictions have even imagined that the message might be encoded in the rock formation of the Grand Canyon, as another example. In our opinion, such suggestions are clearly not universal enough, and they seem to require direct intervention by the Creator during the evolution of the universe. Another possibility, that a message might be hidden deep in the digits of pi or the Riemann zeta function, is also appealing, but we have no way of addressing how feasible that might be without some measure over possible realizations of mathematics. . .

We have convinced ourselves that the medium for the message is unique: it could only be the cosmic microwave background. The cosmic microwave background is in effect a giant billboard in the sky, visible to all technologically advanced civilizations. Since different regions of the sky are causally disconnected, only the Being “present at the creation” could place a message there. (There are also cosmic neutrino and gravity wave backgrounds, but given the elusive nature of neutrinos and gravity waves it seems that photons are a better choice for carriers of the message.)