[SEQ RERUN] Feynman Paths
Today’s post, Feynman Paths was originally published on 17 April 2008. A summary (taken from the LW wiki):
Instead of thinking that a photon takes a single straight path through space, we can regard it as taking all possible paths through space, and adding the amplitudes for every possible path. Nearly all the paths cancel out—unless we do clever quantum things, so that some paths add instead of canceling out. Then we can make light do funny tricks for us, like reflecting off a mirror in such a way that the angle of incidence doesn’t equal the angle of reflection. But ordinarily, nearly all the paths except an extremely narrow band, cancel out—this is one of the keys to recovering the hallucination of classical physics.
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 Quantum Arena, 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.
Did anyone encounter a good response to this comment?
Only the comment that pointed out that the mirror is irrelevant. You can do the exact same calculations about a photon that travels directly from point A to point B.