There you have, then, a theoretical physics which is neither the theory of a believer nor that of a nonbeliever, but merely and simply a theory of a physicist; admirably suited to classify the laws studied by the experimenter, it is incapable of opposing any assertion whatever of metaphysics or of religious dogma, and is equally incapable of lending effective support to any such assertion.

No physicist could tolerate religious dogma or extremism, but I have found that Christianity provides answers to the deeper questions about life and purpose which are beyond the range of science to answer. To me it is nonsense to claim, as some atheists do, that there is nothing worth knowing that is beyond the range of science. Religion is unfashionable in our current materialistic and consumer society, but I have not found Nobel Laureates to be especially atheistic. Accurate statistics are not available, and atheists tend to make more noise, but I know at least 6 examples amongst living physics laureates who are Christians. Being religious means accepting mystery, but so does physics. Things like quantum entanglement, where I can do something to an electron in the lab, and another electron at the edge of the Universe will respond instantly, are not understandable.

I feel I may be controversial in this, but I think that wisdom doesn't count for a lot in theoretical physics. It’s not like history and literature, where you accumulate a broader and broader world view. It’s not a question of energy; I have plenty of energy. I just wrote—just finished writing this massive book...I think most theoretical physicists do their best work when they're young, because they see problems fresh for the first time.

Though the churches, in general, abstained from interfering officially, the scientific activities of the physicists have always been influenced by their private religious views. The latter, of course, were not necessarily identical with the ecclesiastical doctrines, but the philosophical attitudes of the scientists were affected, at least to some extent, by the prevailing religious thought. Kepler, Descartes, Leibniz, and Newton freely acknowledged this influence; it played a part in the principle of least action in the eighteenth century. After this period, in which Kant's philosophy proclaimed the complete independence of scientific understanding and religious belief, not much more about it is found in physical writings. However, this by no means signifies that the investigational urge of later scientists was not intimately connected with their religiosity. The tenet that the scientific experience of truth in any sense is "theoria," i.e., a view of God, might be said sincerely about the best of them. The search for knowledge without regard to its applicability for use has been "an essential trait of man through the centuries, a sign of his higher origin."

I have tried to read philosophers of all ages and have found many illuminating ideas but no steady progress toward deeper knowledge and understanding. Science, however, gives me the feeling of steady progress: I am convinced that theoretical physics is actual philosophy. It has revolutionized fundamental concepts, e.g., about space and time (relativity), about causality (quantum theory), and about substance and matter (atomistics), and it has taught us new methods of thinking (complementarity) which are applicable far beyond physics.

You cannot do physics or cosmology without an assumed philosophical basis. You can choose not to think about that basis: it will still be there as an unexamined foundation of what you do.

In the early 1990s, I came to suspect that the quest for a unified theory is religious rather than scientific. Physicists want to show that all things came from one thing: a force, or essence, or membrane wriggling in eleven dimensions, or something that manifests perfect mathematical symmetry. In their search for this primordial symmetry, however, physicists have gone off the deep end, postulating particles and energies and dimensions whose existence can never be experimentally verified.

By having simplified what is known, physicists have been led into realms which as yet are anything but simple. That at some time, they, too, will appear as simple consequences of a theory of which no one has yet dreamed is not a statement of fact. It is a statement of faith.

Both religion and science require a belief in God. For believers, God is in the beginning, and for physicists He is at the end of all considerations… To the former He is the foundation, to the latter, the crown of the edifice of every generalized world view.

... theoretical physics is less clean than the way it's usually solved. You can always change parameters and save yourself. ... it's very rare that theories are ruled out by just an experiment or a group of experiments. Theories usually come with flexibility. Theoreticians can add flexibility. And so new experiments — you can just patch up your theory.

The confidence placed in physical theory owes much to its possessing the same kind of excellence from which pure geometry and pure mathematics in general derive their interest, and for the sake of which they are cultivated. ... We cannot truly account for our acceptance of such theories without endorsing our acknowledgement of a beauty that exhilarates and a profundity that entrances us.

Physics is my religious belief. In the sense that in physics we discover a fantastically wonderful world out there that’s rich in potential, rich in realization, and that has ample scope for fantasy, because the laws are so strange and there’s so much stuff out there to understand. And when you understand it, you understand how that could be.
I learn that I myself am very small. But I am also very large because I contain multitudes, as Walt Whitman said. I can process information. I can understand things. I can imagine. I can have fun. That’s the essence of my religion. I learn my religion from the study of what the world is and how it works.

At a dinner many decades ago, the physicist Robert W. Wood was asked to respond to the toast, “To physics and metaphysics.” By “metaphysics,” people then meant something like philosophy, or truths you could recognize just by thinking about them. They could also have included pseudoscience. Wood answered along these lines: The physicist has an idea. The more he thinks it through, the more sense it seems to make. He consults the scientific literature. The more he reads, the more promising the idea becomes. Thus prepared, he goes to the laboratory and devises an experiment to test it. The experiment is painstaking. Many possibilities are checked. The accuracy of measurement is refined, the error bars reduced. He lets the chips fall where they may. He is devoted only to what the experiment teaches. At the end of all this work, through careful experimentation, the idea is found to be worthless. So the physicist discards it, frees his mind from the clutter of error, and moves on to something else.* The difference between physics and metaphysics, Wood concluded as he raised his glass high, is not that the practitioners of one are smarter than the practitioners of the other. The difference is that the metaphysicist has no laboratory.

Theoretical physicists live in a classical world, looking out into a quantum-mechanical world. The latter we describe only subjectively, in terms of procedures and results in our classical domain.