Originally Posted by Botnst

#17.

Originally Posted by sjh

The basis of 20th century physics are based on light in vacuo.

The claim that it is also constant in a medium is believed to be correct but is derived from the first sentence which is the basis.

Typically one states the fundamental statement and not the derivatives when discussing the matter.

There actually are no fundamental statements expressing that light is constant in a medium. That is assuming homogeneity and certain properties of matter.

Since we are discussing our most precise discipline, physics, it is beneficial that one learns and expresses the fundamentals.

If a student wrote on a test that the C was constant in a substance when asked the basis for Einstein or Lorentz if they answered as you have stated they would receive partial credit.

I have given a more precise answer. You can argue that empty space is a medium, that's fine. Nevertheless the physicist will state, "in vacuo OR in media if asked for the value of C. Since that is how those in the discipline use the terms that is how I will use it in these conversations.

If arguing that your understanding of the term is such and such that's fine. However, when discussed by those in the discipline the terms are used as I have stated.