Concepts like “time” are not handed to us unambiguously by the outside world but are invented by human beings trying to make sense of the universe.

To this day, scientists haven’t yet determined to anyone’s satisfaction whether the universe will continue to evolve forever, or whether it will eventually settle into a placid state of equilibrium.

For the first time in the history of science, we have at least a chance of putting together a sensible theory of time and the evolution of the universe.

[T]he number of grains of sand on all the Earth’s beaches is only about 10²⁰.

It’s possible, of course, that general relativity is not the correct theory of gravity on cosmological scales ….

Inflation has a lot going for it, but it makes the need for a theory of initial conditions even more pressing.

“In the beginning,” he said, “exactly fifteen point two billion years ago, there was a Big Bang and the Universe–”
I had stopped writing. “Fifteen billion years ago?” I said incredulously.
“Absolutely,” he said. “I’m inspired.”