"A well-known scientist (some say it was Bertand Russell) once gave a public lecture on astronomy. He described how the earth orbits the sun and how the sun, in turn, orbits around the center of a vast collection of stars called our galaxy. At the end of the lecture, a little old lady at the back of the room got up and said: "What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise." The scientist gave a superior smile before replying, "What is the tortoise standing on?" "You're very clever, young man, very clever," sad the old lady. "But it's turtles all the way down!"
Most people would find the picture of our universe as an infinite tower of tortoises rather ridiculous, but why do we think we know better? What do we know about the universe, and how do we know it? Where did the universe come from, and where is it going? Did the universe have a beginning, and if so, what happened before then? What is the nature of time? Will it ever come to an end? Can we go back in time?
Today we still yearn to know why we are here and where we came from. Humanity's deepest desire for knowledge is justification enough fro our continuing quest. And our goal is nothing less than a complete description of the universe we live in."

- Stephen Hawking from A Brief History of Time

A simplified explanation of why I want to study what I study.