Talk:D'Alembert operator

message: D^2 + m or D^2 - m is a matter of convention, because the sign of D^2 is. --MarSch 08:56, 23 October 2005 (UTC)
thread_title:  Klein-Gordon 

message: I've rewritten the article to only mention all alternate notation, but only use the Delta-symbol for the Laplacian which the d'Alembertian is. Comments welcome. --MarSch 09:33, 23 October 2005 (UTC)
thread_title:  conflicting notations 

message: This may be obvious, but I've had a devil of a time confirming it... The D'Alembert Operator is named for Jean le Rond d'Alembert, correct? Seems like that should be mentioned somewhere if it is (as I assume it to) true.--Falcorian (talk) 19:50, 15 May 2007 (UTC)
thread_title: Not so obvious?

message: When I first visited this page I thought my browser was not capable of displaying the symbol. I eventually figured out that the symbol really is a featureless empty square. I wonder if anyone can suggest a way to make this more obvious. I know it says "the four sides of the box representing..." in the text but that's pretty easy to miss.
I note that some pages have a tag warning readers of this issue:
and this warning is still often necessary (see examples at Unicode_and_HTML; in my browsers the Ge'ez and Runic symbols are not rendered) so it is reasonable to expect that a lot of users are still encountering featureless empty squares in aticles that use special symbols, and will be suspicious of \Box. Robert Munafo (talk) 21:31, 6 June 2010 (UTC)
replies: text: This bothered me as well. I was hoping that - by analogy with the greek capital delta - there existed some D'Alembertian character with one or two bolded edges, however I could not find one in use or in any of the common LaTeX sets. Whilst a greek-ish D'Alembertian character has been proposed at least once (here), there sadly doesn't really seem to be any precedent beyond speculation that would empower anyone to use a less ambiguous symbol. I will however add a comment in the lead that will point out that the symbol is indeed a square. Eutactic (talk) 06:58, 7 June 2010 (UTC)
thread_title:  Symbol looks like an undefined character 

message: Something is amiss.  I found a website claiming that although  \partial_{\mu}  is allowed,
 \partial^{\mu}  isn't and in principle, one is actually using a covariant derivative in Minkowski space. Some precision or clarification on that issue would be helpful.TonyMath (talk) 08:24, 14 July 2015 (UTC)
thread_title: Covariant derivative?=

message: Here we can read  \Box = \frac{1}{c^{2}} \frac{\partial^2}{\partial t^2} - \frac{\partial^2}{\partial x^2} - \frac{\partial^2}{\partial y^2} - \frac{\partial^2}{\partial z^2} , but if we have fixed the time metric as  g=\mathrm{diag}(1,-1,-1,-1)   (ie, with  c=1  , I think the value of c shouldn't appear. In my notes it doesn't appear. --JBecerra (talk) 12:55, 22 June 2016 (UTC)
replies: text: What do you mean? It is not obvious that  ?  Later on, if you keep reading, c is set equal to one. Cuzkatzimhut (talk) 14:05, 22 June 2016 (UTC)
thread_title:  Should ''c'' appear

message: The article has a single reference and the link is dead 169.235.95.203 (talk) 19:27, 17 October 2022 (UTC)
thread_title:  Dead reference