There is no harm in doubt and skepticism, for it is through these that new discoveries are made.

We are at the very beginning of time for the human race. It is not unreasonable that we grapple with problems. But there are tens of thousands of years in the future. Our responsibility is to do what we can, learn what we can, improve the solutions, and pass them on.

There are 10^11 stars in the galaxy. That used to be a huge number. But it's only a hundred billion. It's less than the national deficit! We used to call them astronomical numbers. Now we should call them economical numbers.

Physicists like to think that all you have to do is say, these are the conditions, now what happens next?

Philosophers say a great deal about what is absolutely necessary for science, and it is always, so far as one can see, rather naive, and probably wrong.

For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled.