Talk:Conjugate variables

Time versus Lifetime

In the examples section, I changed the word "time" to "lifetime" to make it more accurate and to help not propagate a common misconception. Time itself cannot be part of a conjugate pair because time is just a coordinate. Uncertainty in time itself or spread in time makes no sense since time marches forward for everything in a predictable way and is not variable in a single reference frame (time can be variable from one reference frame to the next, but that is an entirely different concept). What is actually meant is the lifetime of an object. i.e. how long in time an object or a phenomenon exists. For example, when an electron transitions from one atomic level to another, it emits light. The light does not have exactly one frequency but contains a spread of frequencies. The amount of spread in frequency of the light is inversely proportional to the lifetime of the electron's transition, because they are conjugate variables. It is not inversely proportional to the actual time when the electron transitions, which is irrelevant. — Preceding unsigned comment added by 129.63.129.16 (talk) 16:52, 16 November 2015 (UTC)

examples

Time and frequency should be probably: the more precisely we now the time a musical note sounded, the less precisely we know its frequency.

That phrasing is worse, because when you say "we know the time a musical note sounded", readers will think "time" means "duration", which leads to an incorrect understanding. If you really want to press the analogy with the Heisenberg Uncertainty Principle, you would have to say something like, "the more precisely we can associate a particular instant in time with a musical note (that is, the shorter it is), the less precisely we can associate a particular frequency with that note (that is, it will encompass a larger frequency band)." In the context of this page, it's hardly worth the effort to go through all that; I think the way it's written perfectly adequate. Steve 20:47, 31 July 2007 (UTC)

Disambig needed

If someone has time, could they make this page into a disambig. Thanks: --Sadi Carnot 16:52, 5 June 2007 (UTC)

°--182.186.94.77 (talk) 06:47, 26 March 2015 (UTC)

1. Numbered list item

Header text	Header text	Header text
Example	Example	Example
Example	Example	Example
Example	Example	Example

Have mercy!

This article really needs help. For one thing, it ought not read like a graduate monograph. Wikipedia policy says it well:

"...the lead and initial sections of the article should be written in plain terms and concepts that can be understood by any literate reader of Wikipedia without any knowledge in the given field before advancing to more detailed explanations of the topic. While wikilinks should be provided for advanced terms and concepts in that field, articles should be written on the assumption that the reader will not or cannot follow these links, instead attempting to infer their meaning from the text."

For another, it pretends to be friendlier than it is. I'm about to delete its claim

"A more precise mathematical definition, in the context of Hamiltonian mechanics, is given in the article canonical coordinates"

for the simple reason that it is not supported by fact. Recourse to the article on canonical coordinates does not clarify for the nonexpert reader what the concept of "conjugate variables" is, let alone provide a "precise mathematical definition."—PaulTanenbaum (talk) 16:47, 1 March 2010 (UTC)

In an attempt to retain whatever utility might indeed have existed in the sentence I've deleted, I've also created a see-also section, where I've placed a link to "canonical coordinates."—PaulTanenbaum (talk) 16:55, 1 March 2010 (UTC)

I don't think this reads like a graduate monograph--it reads like something written by somebody who would like to write graduate monographs, but can't due to a clue shortage. Unfortunately, I'm not in a position to fix this one. (I was hoping the wikipedia page woulddefine that term in terms themselves undefined. It's a disease. Stevan White (talk) 15:30, 18 July 2012 (UTC)

Conjugate of Action?

in physics, what is the conjugate variable of action S? —Preceding unsigned comment added by 157.193.6.120 (talk) 22:43, 20 January 2011 (UTC)

Not all physical variables have conjugates. Action does not. JRSpriggs (talk) 05:03, 24 April 2012 (UTC)

Wrong, I just added action and density. — Preceding unsigned comment added by 81.71.198.114 (talk) 22:04, 6 April 2013 (UTC)

Something wrong

The product of charge density times potential has the dimensions of an energy density. So charge density cannot be the conjugate to potential according to the definition on this page: the product should have the dimensions of energy times time (i.e. Action). — Preceding unsigned comment added by 2.225.129.250 (talk) 06:02, 19 February 2015 (UTC)