17. one point, from Lecture 17, a group question, short answer, not easy

Relativity At Last! State both of Einstein's postulates of special relativity (.1 apiece).
Whose shoulders did Einstein stand on (.1) and how (.1) for the first postulate?
Whose shoulders did he or might he have stood on (.2) and how (.4) for the second postulate? The point here is that the second postulate has two origins, one experimental and one theoretical, and I want you to give both. I don't think it's trivial to say how the second postulate comes out of these, but I want you to give it a try.

Revised October 8, 1997.