Short answers, pulled from the story.
Optics is the branch of physics that studies the behaviour, manipulation, and detection of electromagnetic radiation and its interactions with matter. It usually describes visible, ultraviolet, and infrared light, but extends to radio waves, microwaves, and X-rays.
Alhazen, also known as Ibn al-Haytham, wrote the Book of Optics, the Kitab al-manazir, in the early 11th century. He rejected the idea that the eye emits rays and argued that light reflects in straight lines from objects into the eye.
Theodore Maiman demonstrated the first working laser on the 16th of May 1960 at Hughes Research Laboratories. The laser was first described as a solution looking for a problem before becoming a multibillion-dollar industry.
Geometrical optics treats light as rays travelling in straight lines that bend at surfaces through reflection and refraction. Physical optics treats light as an electromagnetic wave and explains effects such as interference and diffraction that geometric optics cannot.
The sky is blue because of Rayleigh scattering, which redirects higher-frequency blue sunlight back toward the observer. Because blue light scatters more easily than red, the sun looks reddish through a thick atmosphere at sunrise and sunset.
Total internal reflection occurs when light travelling from a high index of refraction toward a low one strikes the boundary at a steep angle, so all the light is reflected and none is transmitted. As light travels down an optical fibre it undergoes this reflection, allowing essentially no light to be lost over the length of the cable.