Can you tell me anything about Stephen Hawking?
Stephen Hawking was a seminal figure in the science world, very well-known. As an English theoretical physicist, cosmologist, and author/director of research at the Centre for Theoretical Cosmology at the University of Cambridge, his life was science. 
You said he was an author. Can you tell me which books he wrote?
One of his most popular works was a book called The Grand Design, where he paired with Loenard Mlodinow, published in 2010. This work examined the history of scientific knowledge about the universe and explained the 11 dimension M-theory, and also stated that a Unified Field Theory, proposed by Einstein, didn't exist! 
Can you tell me anything else about his discoveries or theories?
So, Hawking was the first person in history to put into the world a theory of cosmology that was underpinned by a union of general theory of relatively and quantum mechanics. What's more, he was a huge supporter of the many-worlds interpretation of quantum mechanics, and it was a large part of his work.
I know nothing about quantum mechanics. Can you tell me something else about that?
Absolutely! Quantum Mechanics (QM), essentially is a fundamental theory in physics that is used to describe the nature of the smallest scales of energy levels of atoms and subatomic particles. Complex stuff. Most theories in classical physics can be derived from quantum mechanics as an approximation valid at large scale, in fact.
Wow. That does sound complicated. I can't say I know much about classical physics, either.
Classical physics
Classical physics refers to theories of physics that predate modern, more complete, or more widely applicable theories. If a currently accepted theory is considered to be modern, and its introduction represented a major paradigm shift, then the previous theories, or new theories based on the older paradigm, will often be referred to as belonging to the realm of "classical physics".
As such, the definition of a classical theory depends on context. Classical physical concepts are often used when modern theories are unnecessarily complex for
Stephen Hawking
Stephen William Hawking (8 January 1942 – 14 March 2018) was an English theoretical physicist, cosmologist, and author who was director of research at the Centre for Theoretical Cosmology at the University of Cambridge at the time of his death. He was the Lucasian Professor of Mathematics at the University of Cambridge between 1979 and 2009.
His scientific works included a collaboration with Roger Penrose on gravitational singularity theorems in the framework of general relativity and the theoretical prediction that black holes emit radiation, often called Hawking radiation.