Originally Posted By: Bill

True, but if there isn't a known way then you will have to come up with a way that wasn't previously known, and then you will have to provide a solid theoretical basis for your new way.

It was redewenur who suggested that there is no known way - not me.

Originally Posted By: Bill
There is a wikipedia article about refractive index that explains the lower speed of light through a medium.

I do not accept wikipedia as THE ultimate reference.