[SEQ RERUN] Can You Prove Two Particles Are Identical? - Less Wrong

[SEQ RERUN] Can You Prove Two Particles Are Identical?

Tue, 03 Apr 2012 11:42:15 +1000

Submitted by MinibearRex • 4 votes • 5 comments

Today's post, Can You Prove Two Particles Are Identical? was originally published on 14 April 2008. A summary (taken from the LW wiki):

You wouldn't think that it would be possible to do an experiment that told you that two particles are completely identical - not just to the limit of experimental precision, but perfectly. You could even give a precise-sounding philosophical argument for why it was not possible - but the argument would have a deeply buried assumption. Quantum physics violates this deep assumption, making the experiment easy.

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 Where Philosophy Meets Science, 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.

5 comments

Alicorn on [SEQ RERUN] Can You Prove Two Particles Are Identical?

2012-04-03T11:51:15.863273+10:00

Fixed your formatting for you.

MinibearRex on [SEQ RERUN] Can You Prove Two Particles Are Identical?

2012-04-04T14:24:03.624379+10:00

Thank you.

What was wrong, by the way?

Alicorn on [SEQ RERUN] Can You Prove Two Particles Are Identical?

2012-04-04T16:35:11.488282+10:00

The HTML appeared in the WYSIWYG editor. I just copied it all and pasted it into the HTML editor instead.

DaveInNYC on [SEQ RERUN] Can You Prove Two Particles Are Identical?

2012-04-07T11:48:54.382171+10:00

In a previous post in this series, it was stated that if you shot the particles towards the mirrors at different times, but that difference was vanishingly small, then you would still see the same results, except for there would be a correspondingly vanishingly small chance that you would see both detectors register a single particle, since configurations were "smudgy". Why would not the same apply to two electrons that were distinguishable, but their differences were vanishingly small?

Oscar_Cunningham on [SEQ RERUN] Can You Prove Two Particles Are Identical?

2012-04-09T20:13:50.161115+10:00

This would work only if the configurations were smudgy along the dimension on which the particles were different, so that the smudges could overlap.