Talk:Kerr effect

message: Do we know what the value of the kerr constant is? I didn't see it anywhere in the article.Strangealibi (talk) 13:04, 11 March 2008 (UTC)
replies: text: The value is different for each material. It's a material constant, not a fundamental constant.--Srleffler (talk) 17:08, 11 March 2008 (UTC)
thread_title:  Kerr Constant 

message: === Symbol for scalar product (== dot product) should be a dot ·, not a colon :. Formula completely wrong? ===
For some reason, "Theory" uses ":" as 
> The ":" symbol represents the scalar product between matrices.
That's a bit … strange, because the scalar product between matrices is otherwise called "dot product" for reasons of it typically being represented by a dot. Maybe this is a special convention in that field? Then again, as an EE with some background in that, I've never read that in a text book for physics students on the topic. So, hm.
But it's also strange, because in the formula
 \mathbf{P} = \varepsilon_0 \chi^{(1)} : \mathbf{E} + \cdots 
the term \varepsilon_0 \chi^{(1)} is not a matrix at all; it really makes no sense to call ":" an operator between matrices.
This undermines all my confidence in the presentation of this formula. It does not help that \mathbf P should by notational convention describe a matrix (since bold), but if these : are all scalar products, then all the summands on the right are scalars, and thus so is the sum. Marcusmueller ettus (talk) 10:36, 15 July 2023 (UTC)
replies: text: There is such a thing as a "colon product," but it isn't necessarily needed here, and to say that it (the colon) represents a scalar product is wrong.  I made some corrections to this ("DC Kerr Effect") section and added a couple of references. Dlinkhart (talk) 20:00, 17 November 2023 (UTC)
thread_title:  DC Kerr Effect Dubious Formula 

message: For some reason, "Theory" uses ":" as 
> The ":" symbol represents the scalar product between matrices.
That's a bit … strange, because the scalar product between matrices is otherwise called "dot product" for reasons of it typically being represented by a dot. Maybe this is a special convention in that field? Then again, as an EE with some background in that, I've never read that in a text book for physics students on the topic. So, hm.
But it's also strange, because in the formula
 \mathbf{P} = \varepsilon_0 \chi^{(1)} : \mathbf{E} + \cdots 
the term \varepsilon_0 \chi^{(1)} is not a matrix at all; it really makes no sense to call ":" an operator between matrices.
This undermines all my confidence in the presentation of this formula. It does not help that \mathbf P should by notational convention describe a matrix (since bold), but if these : are all scalar products, then all the summands on the right are scalars, and thus so is the sum. Marcusmueller ettus (talk) 10:36, 15 July 2023 (UTC)
replies: text: There is such a thing as a "colon product," but it isn't necessarily needed here, and to say that it (the colon) represents a scalar product is wrong.  I made some corrections to this ("DC Kerr Effect") section and added a couple of references. Dlinkhart (talk) 20:00, 17 November 2023 (UTC)
thread_title:  Symbol for scalar product (== dot product) should be a dot ·, not a colon :. Formula completely wrong?