User talk:David edwards

Conjugate quantities

Greetings. Could you review the present state of the article Conjugate quantities, which I redid (see also Wikipedia:Articles for deletion/Conjugate quantities), as well as my recent edit to the lead of Uncertainty principle, and revert/delete/revise as necessary? Thanks. Lambiam ^Talk 11:21, 8 May 2006 (UTC)[reply]

Your recent change to Heisenberg uncertainty principle

You recently made a change to that article replacing the expression "assign values" with "measure values". I am not sure I agree with this change. If A, B are commuting SA operators, it's clear what assigning a value to A, B for a given system state means — even if the system state is a mixed state. A mixed state naturally yields a probability measure on the spectrum of the C*-algebra generated by A, B. In that case, A, B are random variables and have joint probability measures etc. However, no such joint probability measures are possible for non-commuting A, B (somebody or other's theorem -- Maybe Ed Nelson). So I don't think it's entirely correct to say "measure a value" here, since in principle impossible to even assign values with some very mild restrictions. Thanks.--CSTAR 20:39, 9 May 2006 (UTC)[reply]

December 2014

Welcome to Wikipedia. We welcome and appreciate your contributions, including your edits to The Feynman Lectures on Physics, but we cannot accept original research. Original research refers to material—such as facts, allegations, and ideas—for which no reliable, published sources exist; it also encompasses combining published sources in a way to imply something that none of them explicitly say. Please be prepared to cite a reliable source for all of your contributions. Thank you. - DVdm (talk) 09:04, 27 December 2014 (UTC)[reply]

Note - see also wp:secondary sources, and this and this. - DVdm (talk) 10:37, 27 December 2014 (UTC)[reply]