Who was the first to discover the laws of reflection/refraction. Who was known to be the first modern scientist?
I'm not real sure where the study of reflection/refraction (history of optics) specifically began, but most trace it back to ancient Egypt and Greece. Euclid (325-265 BCE) is most noted here, as being the first to treat optics geometrically. But Ibn Al-Haytham (965-1040) is often called the 'father of modern optics' because he was the first to say that light waves entered the eye rather than what most had been saying: that the light waves emitted from the eyes. He also used the scientific method (experimentation) which gavehis theories more justification. He was also one of the initiators of the scientific method, so that alone could qualify him as the first 'modern' scientist.
Greeks and Egyptians had used forms of empiricism, but the scientific method was really developed by Muslim scientists, namely Ibn Al-Haytham (Alhazen). However, I've also often heard Galileo and Newton as being the first modern scientists. But I think their contributions were more epistemological than methodological: all I mean by that is that their predecessors had more to do with establishing science methodology and they had more to do with using/and improving those methods to make even greater discoveries/observations.