If we wish to draw philosophical conclusions about our own existence, our significance, and the significance of the universe itself, our conclusions should be based on empirical knowledge. A truly open mind means forcing our imaginations to conform to the evidence of reality, and not vice versa, whether or not we like the implications.

The universe is the way it is, whether we like it or not.

A universe without purpose should neither depress us nor suggest that our lives are purposeless. Through an awe-inspiring cosmic history we find ourselves on this remote planet in a remote corner of the universe, endowed with intelligence and self-awareness. We should not despair, but should humbly rejoice in making the most of these gifts, and celebrate our brief moment in the sun.

You are all stardust.

I cannot stress often enough that what science is all about is not proving things to be true but proving them to be false.

The real thing that physics tell us about the universe is that it's big, rare event happens all the time — including life — and that doesn't mean it's special.

We now know that we are more insignificant than we ever imagined. If you get rid of everything we see, the universe is essentially the same. We constitute a 1 percent bit of pollution in a universe . . . we are completely irrelevant.