It has to produce radiation patterned so as to imitate interstellar parallax. And it has to physically emit very high energy particles such as we detect on earth in cosmic rays.
It doesn't have to be "perfect". Keep in mind the old joke about the experimental and theoretical physicist:
Experimental physicist: I did an experiment and the sign on constant X came out positive.
Theoretical physicist: It's easy to see that it should be that way because of reasons Y and Z.
Some time later
E: Oops, turns out there was a mistake in my experiment, the sign on constant X should really be negative.
T: It's even easier to see why that should be the case.
Here.
Long story short, it's an attempt to justify the planetarium hypothesis as a solution to the Fermi paradox. The first half is a discussion of how it and things like it are relevant to the intended purview of the blog, and the second half is the meat of the post. You'll probably want to just eat the meat, which I think is relevant to the interests of many LessWrong folk.
The blog is Computational Theology. It's new. I'll be the primary poster, but others are sought. I'll likely introduce the blog and more completely describe it in its own discussion post when more posts are up, hopefully including a few from people besides me, and when the archive will give a more informative indication of what to expect from the blog. Despite theism's suspect reputation here at LessWrong I suspect many of the future posts will be of interest to this audience anyway, especially for those of you who take interest in discussion of the singularity. The blog will even occasionally touch on rationality proper. So you might want to store the fact of the blog's existence somewhere deep in the back of your head. A link to the blog's main page can be found on my LessWrong user page if you forget the url.
I'd appreciate it if comments about the substance of the post were made on the blog post itself, but if you want to discuss the content here on LessWrong then that's okay too. Any meta-level comments about presentation, typos, or the post's relevance to LessWrong, should probably be put as comments on this discussion post. Thanks all!