In their book The Grand Design, Hawking and Mlodinow explain the way theories about quantum mechanics and relativity came together to shape our understanding of how our universe (and possibly others) formed out of nothing.
Hawking is eloquent in the way he describes and explains the workings of the universe.
Orbital eccentricity is a measure of how near an ellipse is to a circle. The degree to which an ellipse is squashed is described by what is called its eccentricity, a number between zero and one. The earth’s orbit has an eccentricity of only about 2 percent, which means it is nearly circular. Circular orbits are friendly to life, while very elongated orbits result in large seasonal temperature fluctuations. On Mercury, for example, with a 20 percent eccentricity, the temperature is over 200 degrees F warmer at the planet’s closest approach to the sun (perihelion) than when it is at its farthest from the sun (aphelion). (p. 150-151)
In 1992 came the first confirmed observation of a planet orbiting a star other than our sun. We now know of hundreds of such planets, and few doubt that there exists countless others among the many billions of stars in our universe. That makes the coincidences of our planetary conditions–the single sun, the lucky combination of earth-sun distance and solar mass–far less remarkable, and far less compelling as evidence that the earth was carefully designed just to please us human beings. Planets of all sorts exist. Obviously, when the beings on a planet that supports life examine the world around them, they are bound to find that their environment satisfies the conditions they require to exist. The fact of our being restricts the characteristics of the kind of environment in which we find ourselves. (p. 153)
Hawking also discusses and explains things such as geodesics, the forces of nature, and how all chemical and organic elements were originally formed. I recommend reading this book to fully appreciate and understand how everything fits together.
The Grand Design is fascinating. It was not a difficult read, as it had no confusing mathematical equations, yet it was interesting, detailed, and thought-provoking. It definitely peaked my curiosity further in physics and cosmology.