Today's post, Which Basis Is More Fundamental? was originally published on 24 April 2008. A summary (taken from the LW wiki):

The position basis can be computed locally in the configuration space; the momentum basis is not local. Why care about locality? Because it is a very deep principle; reality itself seems to favor it in some way.

Discuss the post here (rather than in the comments to the original post).

This post is part of the Rerunning the Sequences series, where we'll be going through Eliezer Yudkowsky's old posts in order so that people who are interested can (re-)read and discuss them. The previous post was The So-Called Heisenberg Uncertainty Principle, and you can use the sequence_reruns tag or rss feed to follow the rest of the series.

Sequence reruns are a community-driven effort. You can participate by re-reading the sequence post, discussing it here, posting the next day's sequence reruns post, or summarizing forthcoming articles on the wiki. Go here for more details, or to have meta discussions about the Rerunning the Sequences series.