Just because you call it hand-waving doesn't make it so. There really is no plausible method by which a measurement process resulting in that LCD screen being read is undone, resulting in a state universally identical to one in which the opposite measurement had been made.
I don't disagree with your second sentence. Regarding the first, I don't think there's really any argument about whether or not it's handwaving. The question is whether or not it's justified handwaving in the pursuit of a pseudo-rigorous understanding of quantum mechanics.
I'm comfortable with him saying that time evolution is linear, because there are intuitive reasons for it to be so, and he presents those reasons elsewhere.
I'm less comfortable with the use of them in this article. Take the following quote:
...There are no plausible Feynman paths that end u
Today's post, On Being Decoherent was originally published on 27 April 2008. A summary (taken from the LW wiki):
Discuss the post here (rather than in the comments to the original post).
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