All science is either physics or stamp collecting.
Ernest Rutherford, or Lord Rutherford as the British Royalty approved, was a physicist of the early 20th century. One of his most well-known (famous or notorious) words is the above one, but it is communicated in many different forms and I have not been able to determine what was the original form. The sentence quoted above follows Richard Gallagher and Tim Appenzeller (1999, Science 284, 79), and the title of this page is my modification of it which I think (hopefully) to be still within the variability of the quotation.
"Stamp collecting" usually means to collect postage stamps, and it does not sound like science. Admittedly, it may be related to some subjects of social science (What was the role of postal service in a certain country? Who were considered national idols recognized by both the people and the national authority? ...) But they cover just a tiny part of science. Therefore, the phrase is often considered that Rutherford thought, or collectively physicists think, that disciplines of science other than physics are not real science. Of course it made some scientists other than physicists angry.
But, let's think about natural stamps. When I was a high school student, I was a member of a group that dug cliffs made of silt which contained mollusc shells or tree leaves. Sometimes calcium carbonate of shells or carbon of leaves remained, but often they had been dissolved into the silt. The shape could be recognized as gravure of the silt. Don't we call them stamps (in common words, not in scientific terminology)? The stamps we collected were about a few hundred thousand years old, very new in the perspective of the history of the earth, and the species were probably the same as modern ones. So we did not treat our collections as scientifically important ones. It is sure, however, that collections of stamps hundreds of million years old are important to science, even to physics for such questions as whether the constant of gravity is really constant or changing in the time scale of hundred million years.
On the other hand, what was physics to him? The most famous achievement of Rutherford was about the structure of atoms. It had been known that electrons which have negative electrical charge can be isolated from atoms. Probably they exist in the atoms. Then how the positive charge that compensates for the electrons' charge exists in an atom? J.J. Thomson hypothesized that it would be distributed all over the atom, while H. Nagaoka considered that it would be concentrated at the center. Rutherford made an ingenious experiment that effectively disproved (falsified) Thomson's hypothesis and tentatively supported (corroborated) Nagaoka's. This is probably a good example of what he meant by "physics." (Note: Words in the above parentheses are technical terms used in Karl Popper's philosophy of science, which I would like to discuss in another occasion.)
Ironically speaking, Rutherford's experiment may also be seen as a very special kind of stamp collection like establishing a post authority and publishing its own stamps.
I think that science consists of physics AND stamp collection, and that both parts are essential.
I have got a e-mail message saying that I mis-interpret what Rutherford meant. Perhaps that remark is right, though I cannot say so confidently either. Please do not consider my essay as a serious comment about Rutherford. My intention is just to mention what I thought about science when I heard the old saying. Actually, I got the concept of the essay (except the paragraphs specifically referring to Rutherford's experiment) before I learned whose phrase was that.