Reading is becoming a kind of specialist activity, and that strikes terror into the heart of people who love reading.

While there's life, there's fear.

Romance is tempestuous. Love is calm.

Things on a very small scale behave like nothing that you have any direct experience about. They do not behave like waves, they do not behave like particles, they do not behave like clouds, or billiard balls, or weights on springs, or like anything that you have ever seen.

It's the way I study - to understand something by trying to work it out or, in other words, to understand something by creating it. Not creating it one hundred percent, of course; but taking a hint as to which direction to go but not remembering the details. These you work out for yourself.

It is in the admission of ignorance and the admission of uncertainty that there is a hope for the continuous motion of human beings in some direction that doesn't get confined, permanently blocked, as it has so many times before in various periods in the history of man.

We do not know what the rules of the game are; all we are allowed to do is to watch the playing. Of course, if we watch long enough, we may eventually catch on to a few of the rules. The rules of the game are what we mean by fundamental physics.

It is a curious historical fact that modern quantum mechanics began with two quite different mathematical formulations: the differential equation of Schroedinger and the matrix algebra of Heisenberg. The two apparently dissimilar approaches were proved to be mathematically equivalent.

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.

I was a very shy character, always feeling uncomfortable because everybody was stronger than I, and always afraid I would look like a sissy. Everybody else played baseball; everybody else did all kinds of athletic things.

If I get stuck, I look at a book that tells me how someone else did it. I turn the pages, and then I say, 'Oh, I forgot that bit,' then close the book and carry on. Finally, after you've figured out how to do it, you read how they did it and find out how dumb your solution is and how much more clever and efficient theirs is!

The fact that the colors in the flower have evolved in order to attract insects to pollinate it is interesting; that means insects can see the colors. That adds a question: does this aesthetic sense we have also exist in lower forms of life?

Trying to understand the way nature works involves a most terrible test of human reasoning ability. It involves subtle trickery, beautiful tightropes of logic on which one has to walk in order not to make a mistake in predicting what will happen. The quantum mechanical and the relativity ideas are examples of this.

I think that when we know that we actually do live in uncertainty, then we ought to admit it; it is of great value to realize that we do not know the answers to different questions. This attitude of mind - this attitude of uncertainty - is vital to the scientist, and it is this attitude of mind which the student must first acquire.

It always seems odd to me that the fundamental laws of physics, when discovered, can appear in so many different forms that are not apparently identical at first, but, with a little mathematical fiddling, you can show the relationship.

The original reason to start the project, which was that the Germans were a danger, started me off on a process of action, which was to try to develop this first system at Princeton and then at Los Alamos, to try to make the bomb work.

Once you have a computer that can do a few things - strictly speaking, one that has a certain 'sufficient set' of basic procedures - it can do basically anything any other computer can do. This, loosely, is the basis of the great principle of 'Universality'.

We get the exciting result that the total energy of the universe is zero. Why this should be so is one of the great mysteries - and therefore one of the important questions of physics. After all, what would be the use of studying physics if the mysteries were not the most important things to investigate?

What goes on inside a star is better understood than one might guess from the difficulty of having to look at a little dot of light through a telescope, because we can calculate what the atoms in the stars should do in most circumstances.

It is always good to know which ideas cannot be checked directly, but it is not necessary to remove them all. It is not true that we can pursue science completely by using only those concepts which are directly subject to experiment.

The philosophical question before us is, when we make an observation of our track in the past, does the result of our observation become real in the same sense that the final state would be defined if an outside observer were to make the observation?

I think equation guessing might be the best method to proceed to obtain the laws for the part of physics which is presently unknown. Yet, when I was much younger, I tried this equation guessing, and I have seen many students try this, but it is very easy to go off in wildly incorrect and impossible directions.

When I was a young man, Dirac was my hero. He made a breakthrough, a new method of doing physics. He had the courage to simply guess at the form of an equation, the equation we now call the Dirac equation, and to try to interpret it afterwards.

Today, all physicists know from studying Einstein and Bohr that sometimes an idea which looks completely paradoxical at first, if analyzed to completion in all detail and in experimental situations, may, in fact, not be paradoxical.