# I Experimental investigation of c in electric & magnetic fields

1. Jan 12, 2017

### 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?

2. Jan 12, 2017

### mpolo

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.

3. Jan 12, 2017

### Staff: Mentor

Can you post a link the the paper and direct us to the part you are not understanding?
∇n < 0 would imply what, given the Wikipedia definition of birefringence...

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

4. Jan 13, 2017

### mpolo

5. Jan 13, 2017

### 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.

6. Jan 13, 2017

### mpolo

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

7. Jan 13, 2017

### Drakkith

Staff Emeritus
8. Jan 16, 2017

### mpolo

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

9. Jan 16, 2017

### Drakkith

Staff Emeritus
To quote from the paper so others can see:
I confess that I don't have the knowledge to answer your question.