Existing matter seems highly redundant, and building a full-scale 1:1 replica, as it were, means you cannot opt for any amount of approximation by definition or possible optimization.
I would draw an analogy to NP problems: yes, the best way to solve the pathologically hardest instances of any NP problem is brute force, just like there are probably arrangements of matter which cannot be calculated more efficiently by computronium than the actual arrangement of matter. But nevertheless, SAT solvers run remarkably fast on many real-world problem and far faster than anyone focused on the general asymptotic behavior would expect, and we have no reason to believe the world itself is a pathological instance of worlds.
I don't find this argument persuasive or even strong. n qubits can't simulate n+1 qubits in general. In fact, n qubits can't even in general simulate n+1 bits. This suggests that if our understanding of the laws of physics are close to correct for our universe and the larger universe (whether holographic planetarium or simulationist), simulation should be tough.
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!