[Theory is] an explanation that has been confirmed to such a degree, by observation and experiment, that knowledgeable experts accept it as fact. That's what scientists mean when they talk about a theory: not a dreamy and unreliable speculation, but an explanatory statement that fits the evidence. They embrace such an explanation confidently but provisionally - taking it as their best available view of reality, at least unil some severely conflicting data or some better explanation might come along.

What do we measure when we measure time? The gloomy answer from Hawking, one of our most implacably cheerful scientists, is that we measure entropy. We measure changes and those changes are all for the worse. We measure increasing disorder. Life is hard, says science, and constancy is the greatest of miracles.

I used to read only fiction. Now I don't read much, only occasionally, such as a Cormac McCarthy or a Jim Harrison novel.

Results "are no good unless they answer (or can be made to seem to answer, or can be twisted and wrenched and piled into odd shapes until they hint at being somehow perhaps on the verge or answering) a question that someone might conceivably want asked."

There was a very important superintendent of Yellowstone, a man who was involved in the founding of the National Park Service itself, Horace Albright. And he became superintendent, which is the boss of Yellowstone Park, in 1919 - from 1919 to 1929. Later, he was director of the park service itself. Albright embraced the idea that in order for the national parks - and Yellowstone in particular - to have support from the American people and from politicians, there needed to be wildlife as spectacle.

If you're Maasai Mara National Park in Kenya, if you're in Serengeti National Park in Tanzania, you don't get out of your vehicle and go walking around amid the lions and the leopards. You stay in your Land Rover. You stay in your safari van, and you look out the windows or you look out the pop top at these animals. I know by experience how badly that can work out if you violate those guidelines.

Among the earliest forms of human self-awareness was the awareness of being meat.