What does Δn < 0 mean in light speed measurements in magnetic fields?

[mpolo]

I have been researching a question I have concerning the speed of light in magnetic AND electric fields. I came across an article in arvix but could not quite understand what they were saying. I am not a scientist I am just curious. There was a statement in which was shrouded in a strange nomenclature. Can someone please decipher what they are saying. They said, "In the experimental setup described there, this would mean a birefringence with 0 n (small triangle which I think means delta) <.
Sorry that I could not find the delta symbol. This experiment was referring to measuring the speed of light in a magnetic field and in a vacuum.
What does 0 n small triangle followed by a less than sign mean?

 

[mpolo]

> click on the ∑ symbol in the menu bar at top of text entry box .

I need to make a correction to the formula. it is that the birefringence is delta n < 0 What are they saying about the speed of light here? This is confusing. Thanks for the help.

 

[berkeman]

I came across an article in arvix but could not quite understand what they were saying.

Can you post a link the the paper and direct us to the part you are not understanding?

the birefringence is delta n < 0

∇n < 0 would imply what, given the Wikipedia definition of birefringence...

https://en.wikipedia.org/wiki/Birefringence
$$∇n = n_e - n_o$$

 

[mpolo]

Https://arvix.org/ftp/physics/papers/0703/0703271.pdf

 

[mpolo]

The paragraph number 2.
I need to have this spoken to me in payments terms. It looks to me as if the experiment is supposed to yield a positive value but the person or lab measured a negative value. How does this relate to the speed of light.

 

[mpolo]

Sorry I am on a trip and using a cell phone. In the paragraph above I meant laymens terms not payment terms.

 

[Drakkith]

Https://arvix.org/ftp/physics/papers/0703/0703271.pdf

That link doesn't work for me (I get a "Forbidden" error). If I switch the v and the x the link works fine though:

https://arxiv.org/ftp/physics/papers/0703/0703271.pdf

 

[mpolo]

Yes typed it wrong. Your link is proper. Why is the negative value a problem concerning birefringence. Does anyone know?

 

[Drakkith]

Yes typed it wrong. Your link is proper. Why is the negative value a problem concerning birefringence. Does anyone know?

To quote from the paper so others can see:

In the experimental setup described there, this would mean a
birefringence with ∆ <n 0 . The problem is, that the result of this experiment is in clear contradiction
with the theoretical predictions mentioned above, and furthermore it shows some artefacts
[Lam 07] which make the probability of a real result rather uncertain.

I confess that I don't have the knowledge to answer your question.